It's annoying I know, but the reason I'm hoping to build a Patreon audience is that TH-cam pays about $10 per 10,000 views! When I put 100+ hours into a video like this my hourly rate is, no joke... 20 cents. 😂 If you think this bike knowledge is worth more than 20c per hour, consider supporting the channel here: www.patreon.com/cyclingabout
I find you to be quite knowledgable about bikes. Would love to buy one of your books. Do you do print as well? Also do you have a background to engineering.
I agree with your video for the most part, but one caution: comfort is not only about flex, it is also about vibrations. I found carbon to be better at dampening vibrations (trail chatter). I had an alloy Scott Scale, before replacing it with a carbon version. Seat flex was marginally different (I could not really tell was it slightly less or more cause seatposts were almost identical) but the vibrations were way quieter. If you owned two almost identical bikes one after another, with the main difference the frame material, I believe you would have a different experience. I think it is a good example cause both bikes were equipped with almost identical Syncros hardware and wheels (Scott's own indoor brand). And tyres were same size, similar pattern and composition, with me always having identical air pressure.
Great video. I love steel bikes, not just for their supposed comfort, but I agree with everything he said. Tire width and pressure matters far more than anything else for bump absorption. After a lifetime of futzing with bikes, including working as a mechanic, I think that most of what bike nerds obsess about just doesn't matter (unless you race bicycles to earn a living). The older I get, the less fussy I am about parts, and the more I enjoy just riding.
Something not explored in this video is the frequency range of vibrations; they cover a spectrum depending on road surface and what obstacles you encounter. With similar setup when riding on the roald, I've always had the unmistakable impression that steel damps the higher frequency vibrations better than carbon resulting in a more velveting road feel that I simply haven't experienced on a carbon bike.
Yeah totally agree. Everything dampens different vibration frequencies differently. I think the cream of the crop for smooth frame materials is bamboo. I built a bamboo hardtail and it is night and day smoother than any other bike i have ridden
@@mog3680 i like to cuddle with my bikes naked frame (no components on) and watch videos of the course im going to ride. so i can feel in tune with the frequency of the bike and match the frequency of the road so everything is in harmony. makes the ride so smooth like gliding on a cushion of air. similar to air hockey puck. sooo good
Is the fork considered not part of the frame? On many vintage bikes you can see the fork flex if you pull the front brake and try push the bike forward. How about vibration dampening? Sorry but the seatpost flex test seems too simplistic to paint the whole picture. Youre correct that tyres and saddle etc play a huge role though, not arguing that.
I agree. I have two Hardtail MTB frames which I push to the extreme downhill. (Same geo and I use pretty much the same parts on them) I can definitely feel a difference between my steel and alloy frame hardtails. The steel is not only faster but also more comfortable. The tubes are smaller and they also swing and vibrate completely different. He is just talking about but comfortable but not the difference between steel and other materials.
I noticed that the fork was ignored too. Maybe that complicated the message too much? Even among my steel road bikes, I can tell that some flex more than others, and a bit of flex does help reduce the vibration that gets to your hands.
Great video, but forgot to introduce the advantage heavier frames have in terms of comfort simply due to higher inertia. It's the same when you attach bottles and bags to your bike--it becomes more comfortable to ride because the bike simply can't rattle you as much as lighter bikes can. This is probably one reason for why people believe steel bikes are more comfortable. They may be, but not if you compensate for the weight difference, for example by attaching weights to a carbon frame.
I think people mistake the feel for comfort. I find a steel bike feels springy but I wouldn't say it's a more comfortable ride. Hitting a pothole on any roadbike will be jarring.
I clicked on the video with an attitude: “Oh yeah? Change my mind!” Well, thanks for changing my mind! You have a great way of stripping away the hubris and spookiness and bringing science to the forefront. 👏
I'm glad you went and put some numbers and tests to this. The conclusion also feels pretty correct. I changed from a 700 28C to a 29er MTB and the comfort I get from these BIG tyres make much more of the difference, also the seat post and saddle, play in that equation.
I actually started road riding on that EXACT same steel trek (my dad's old bike), then 20ish years ago when I finally bought a modern GURU road bike with aluminum lugs and carbon tubes the difference in stiffness was MASSIVE (the carbon bike had what felt like absolutely zero flex or peddle bob and my feet would go numb from road vibrations...it made the steel trek bike feel like a full suspension bike!). So I'm not sure how much I really agree with the results here, at least my interpretation of them...
All true of my experience as well, but the video is correct; it's likely to be better geometry and more pliant seatpost/wheels/tyres that do the job so well on those old bikes. The reason to choose steel is resiliency. I've snapped a steel bike while riding it... it carried on riding, because it bends rather than breaks. I've snapped aluminium and wiped out dangerously, because just like carbon/resin, aluminium fails suddenly and catastrophically. Therefore, steel.
Its almost certainly the differences in GEOMETRY you are feeling, not material. Also as mentioned in this excellent video: , tire size, tire pressure, tire material, saddle design and positioning, handle bar tape, set post, fork design.
@@j.k.cascade2057 hmm I ran the same tubes and tires and saddle on both bikes. I could see the wheels causing a difference in compliance though. But they were just completely different bikes, night and day difference in stiffness, compliance, power absorption/efficiency...it was noticeable on the first couple of peddle stokes and even more glaring during sprints, the trek would bob like a dual suspension bike.
I've known for a long time that changing your seat post to say carbon, can make a stiff uncomfortable bike less taxing to ride. Thanks to you now I know why.... great video.
I think most of it comes from when aluminium bikes were fairly new. I am old enough to remember. I had a Bridgstone RB1 (a now legendary frame) and I could feel a little bit of flex in the bottom bracket when I'd sprint or stand to climb. In 1991, I bought a new Cannondale and the ride was very different. It was much more harsh, but there was no detectable flex in the bottom bracket. I loved that bike even though the stiff frame combined with the high pressure 18c and 20c tires brought a very jarring ride. Aluminum design has greatly improved since then but the image has not for a lot of people
I loved my Aluminum trackbike. Though it was VERY harsh. I learned to ease on sitting the saddle. So I was mostly on my legs while riding it. Though they are ment to be rigid and to be ridden just a short time.
Read about the differences/development of alloy during time. Giant did some great work evolving from 70 to 60 Aluminium which gives a smoother ride being more flexible. roadcyclinguk.com/gear/giant-defy-aluminium-range-overview.html
It comes from normal bikes, not high end bikes. 95% of the bikes out there are cheap. And Aluminium has to be overbuilt to be safe. It's true there have been advances from big manufacturers understanding aluminium better since after the 1990s. But a lot of those 90s bikes are still on the road (which is awesome, bikes are such a great durable vehicle.) And loads of bikes nowadays are still build that way. Aluminium welding and metal fatigue, heat treatment, these are tricky. With steel you can do that in your garage. Most Aluminium is stiffer, even if it is not inherent to the material itself.
Cool. I still have my RB-1 that I bought new many moons ago. Love it . I've squeezed 32 slicks on it and have taken it on MTB trails and loaded it down with touring bags. But getting a gravel bike now that will better suited for those things. A steel one.
Thanks for the informative video. You inspired me to buy a Brooks B 67 saddle for my Cube travel bike. I remember how comfortable my English 3 speeds were with their sprung Brooks saddles. After so many years on 23c tires, I am also loving the 2.2's tires. I can run the pressure down to 30 psi and they still roll great and give a soft ride. I have also started running 25c's on my Giant TCR. I guess as I get fatter, so do my tires
I've tried steel, carbon, aluminum, titanium, and looked at trying magnesium alloy. Honestly, I haven't felt a difference outside of the stance, ride position, and tire width. I ride steel now on both my hardtail and my gravel bike. The only reason I do this is price. Steel frames are so much cheaper to find and build, giving me more money to spend where it really counts. I'm not a weight weenie, I would rather have a comfortable ride over a particularly fast one. Great video! glad I was not the crazy one who couldn't feel a difference in frame material.
Good to hear. I'm glad it's not just me too! Steel frameset options are definitely great value for the price, it's hard to find anything close in other materials.
I’ve found similar. Steel is nice/practical to live with. Whilst they tend to have ‘a feel’ I’ve not found them to be more compliant or more comfortable.
Try finding a steel enduro hardtail frame for cheaper than some aluminum one. I wish you good luck :D It's crazy how expesnive new steel frames are. Barely can find any used ones and then they still want alot of money because steel is real blaa blaaa
@@kaedeschulz5422 You're right, the steel fad has driven up price. Just recently I have had issues finding a cheap older style steel road frame to build a custom road bike for my dad. Steel is real all right, a real pain to find at a decent price now. My steel XC hardtail is based off Kona's 2015 Unit frame. Their frames did run ~300-400 depending on the bike you want and the Unit is steel. Their sizing is pretty good too with many in-between options and fairly cheap used. You can likely pick up a used Unit single speed cheap and get the sliding dropouts from paragon steelworks to attach a rear derailleur. Those dropouts fit most single speeds with those style slides to open up some possibilities. Tons of options but your right, price is not there like it use to be when carbon was king and steel was a steal.
The thing that gets me is you can get a custom steel frame for the price of a really nice carbon or Aluminum frame... For most people custom steel will be lighter, and should always fit better, presuming everything is got right...
Food for thought. I have steel frame Surly fatbikes, and love them for a number of reasons. I agree that tire size and pressure will always be a dominant factor in comfort and performance. Tires are your (or part of) your suspension, even in a car. I’d say this data is most focused at road bikes, where the tires are small and high pressure.
I think at certain point too big tires will make the ride more sluggish. Around 35c might be the optimal spot. Double butted heat treated steel seems to have more springy horizontal compliance without being too noodly which reduces back pain and gives the feeling of so called ride flow. In my experience budget grade aluminium frames were harsh and clunky regardless of tire pressures while also having high speed shimmy on descents.
@@uvwuvw-ol3fgi think diameter also applies to the equation too since my 26” MTB is quite nimble on it’s 2 inch wide tires where as my Hybrid 700c bike on 32mm tires is quite sluggish in comparison.
I am not scientist but I personally feel steel more comfortable-specifically because I have 2 bikes one a steel and one Alu-frame. It depends on the style on frame.Alu frame can only “flex” one time😂
I am currently resurrecting my 1998 Surly Karate Monkey. Owning 12 bikes, and gone through Alum, to Titanium, to Carbon, now making my way back to the Safety of Steel. Only a couple pounds more weight, but a TON more reliability.
There's no denying a steel bike rides differently. I have 2 road bikes, a steel and carbon. While the carbon does everything better, it lacks character. It feels numb. The steel bike feels "springy" like a spring. Probably because it doesn't dampen the road inputs like carbon. So you like a plastic, stiff yet compliant bike with no character, buy carbon. I'm going to get a modern steel bike and sell my carbon bike.
@@Cyclingabout should be part of the equation, i think. especially when considering, that bumps through the hands and arms are much more noticeable than through my (considerable) behind. curved steel fork with a forged shoulder is slightly, but noticeably more comfy than my aluminum fork (same wheels).
@@FriedrichSchmidgall It also makes a big difference just how the bend is formed. A '30s or '40s fork with a Russ-type bend at the bottom gives huge compliance to cope with cobble-stones, but a shallow curve half way down the blade will not give much. I would add that radial spoked front wheels also give a very non-compliant ride, and I prefer a tangentially spoked wheel.
High quality steel frames are a much smoother ride. Double butted thin walled steel frames have muluiple reasons for better comfort. High end steel tubing is highly resistant to fatigue, meaning flex can and is built into the tubing. The tubing in steel frames is much smaller diameter due to higher strength and fatigue resistance so flexes with less force. Most mocdern bikes are built on a compact design, short tubes and short wheelbase. This does two things, short tubes are much less flexible than long tubes, the wheels are directly under the rider transfering road shock and vibration. Any such frame is much more harsh to ride. Comparing a large size Giant defey advanced 2013 with my current steel framed bike. Steel frame is 16 cm longer wheelbase, no foot front wheel overlap, very smooth ride and only 1 kg heavier. Frame design and frame material both matter for ride quality as do wheels, spoke lacing, rim width, and tyre size
@@Pellagrah Mine is a custom build, while I am only 180 cm tall more 50 years ago a heavy build 110 kg and 46 cm c-c bars. Down tube 28.6 mm Reynols 853 every thing else is 531, centre front 63 cm,
54 cm centre rear. Basically a long wheel base touring bike but built fairly light, could go lighter but 110 kg rider. Wheels are Novatec hubs DT Swiss R500 rims with mini V brakes, 24 DT Swiss revolution spokes front and 24 champion spokes rear rear chainstay are offset to remove the disk in the rear wheel. 32 Conti 5000, Shimano 105 10 speed
@@Pellagrah Most bikes are built on the same plan. To fit in the smallest box possible because transport (container space) is very expensive. Steel is also the easiest to build custom to fit the rider. either lugged is best, fillet braze requires more operator skill as does TIG welding.
Interesting. I switched from a steel HT rigid MTB to an Alu HT rigid Mtb, and I actually got bruises on my love handles. Everything was exactly the same except for the frame and the seat post. The seatpost on the Alu frame was actually not as biffy and straight as on the steel frame.
If your steel bike is heavier, all other factors being equal: it will be more comfortable. More weight = less deflection = less rattling = more comfort. Our friend in the video forgot to mention how weight basically 'outweighs' all the other factors he researched ;).
@@Coerced I took up bike packing and noticed when I added about 12kg to my 26 aluminium hard tail , it was a smoother ride , i could coast the bike easier when going down hill or flat , lots of pros , obviously uphill different story 1🤣 . I wonder if steel bikes can feel smoother cause they are often a bit heavier and coast and ride minor bumpss easier with the weight improving gravity
In terms of comfort, I would suggest saddle choice can make a large difference as well. The more your saddle conforms to your shape and distributes the load out to your contact points, the more comfort you will have. I've ridden Selle SMP saddles for years, even though they are ugly as sin, because they fit me better than other saddles and have made a huge difference in comfort.
Since sides and nose of the saddle is hard then horizontal compliance/springiness of the bike frame is still important when it comes to giving that feeling of so called ride flow and reduction of back pain similar to therapeutic horse riding.
I agree. And no, saddles are meant to be a hammock, not a simple spring. That kind of reductionism leads to ignoring evidence in favour of theory. And in theory practice is the same as the theory. But in practice, well...
As a man who lived off an aluminum bike for over 3,000 days (until the frame fatigue cracked) I completely agree. On a steel frame, the difference is enormous.
I have ridden several mid 90's steel mountain bikes that were very stiff feeling (as much as an Alu bike feels to me). And I've also ridden an early 2000's On-One Inbred (a cult british, taywan made steel hardtail with thin tubes, a long top tube geometry and Dekerf style fork rear stays). The Inbred has always felt noticeably less harsh on the trail when compared with the thicker tubed, shorter "triangled" bikes of the 90s. I've always felt that the zingy feel of the On-One comes from the frame twisting "sideways" relative to the vertical plane as opposed to the vertical movement you are focusing on in the video. My intuition attributes this extra flex to: thinner walled tubes (they bend more easily), smaller diameter tubes (also bend more easily) and a significantly longer top tube (triangles with longer sides, twist more). As concluded in the video It is not surprising that a structure that has its maximum strength in the vertical direction does not deform a lot in that direction. BUT, when riding a bike in the real world, the purely vertical loads are far from being the only forces that define how a bike feels, especially when the bike is tilted/leaned on by the rider and goes around corners and the wheels hit obstacles and bumps that impart lateral forces on the wheels. These more "lateral twisting" forces are probably way more important to ride feel and comfort than the vertical ones. (precisely because most frames are designed precisely to guarantee they are very strong in this direction. For the counter point consider something like the Slingshot mountain bikes of the 90s, the ones where the down-tube was a tensioned cable. Look at the lateral flex on those bikes!) Don't forget that all key components that are in between the force "origins" and the frame are nowadays typically very stiff. Namely: the rims, hubs and spokes, the fork, the pedals, cranks and bottom bracket. Also don't forget that most frames nowadays (even steel ones) are built to be very laterally stiff, because this is a sort of assumption by manufacturers that stiffness is a desirable property in general. This is a symptom of the influence of road bike racing (the stiffer the less energy is wasted) and of mountain bike design where in the last few decades everything from handlebar diameter, to fork stanchions, to head tubes to axle diameters became oversized in the quest for more stiffness. I'd love to see new tests done by applying a twisting force via a lateral load to the front view axis of the steered tube for example (with the rear dropouts affixed to a solid stand). I do reckon such tests would show that this torsional frame stiffness is more dependent on the actual tube specs and frame design, than the materials per se. These are just the ramblings of a non-engineer that has been riding bikes for 40 years. So take that as you will :P
I've owned/ridden steel, aluminum and carbon, and I can't tell the difference. I have never experimented with seat stems. In my experience it's tires that make the most difference.
Agreed I switched my hybrid to road tires and it helped but that aluminum frame still buzzes and puts my hands to sleep 😔😔. The problem turned out to be that the frame was slightly to big causing me to ride in a bad position because of the reach . My light weight aluminum road bike still climbs better so weight is definitely an improvement and not a myth 😂😂👍👍.
I think when they're comparing steel, titanium, aluminum and carbon in terms of comfort, they refer mostly to vibrations that are transmitted through the frame material and not visible or measurable flex. The way the frame resonates does give a slightly different 'feel' to the bike, but you have to know how to distinguish it.
There was a study a few years back on fatigue to feet and legs, which included micro-injuries caused by vibrations and shock. The cumulative damage and fatigue can be very substantial in some situations (long off-road touring, for example). I have bikes made of different materials and designed for different purposes. I've noticed a lot of compliance - but not VERTICAL compliance - in some of the steel frames. It is more like torsional compliance. I can feel a major difference going over sharp bumps and rough surfaces at times. It's the sort of flex you can experience when you're off the bike, and putting one foot on a pedal at the six o'clock position, and then repeatedly applying a lot of your weight to that pedal, especially when the bike is held at an angle away from you. Other things are flexing also, but the frame flex is very substantial in some bikes when doing this. I haven't thought much about how this plays out while riding, but I have noticed a "spring" in some steel frames that is other than vertical, and yet very attractive. It makes for a lively, desirable, and more comfortable ride.
Yes, if the labs measured deflection of the frame only from the dropout (why not at the bottom bracket?) and only in a vertical plane, then it is not relevant to the act of bike riding at all because as you say - the bike is always at an angle to the ground. This argument he is making is akin to saying that a bike being aero on the track (no wind) is going to be accurate to the aero-ness in the open road (lots of wind everywhere). Why wouldn't they measure from the bottom bracket since that's where vibrations are transferred to the cranks, bb, and legs - and its the legs that we want to keep fresh to ride longer!
I like the way my steel bikes ride too. If you can build them to have that perfect amount of torsional compliance, where there is noticeable but very minor amounts of flex - it's a really nice feeling (and it's hard to replicate with aluminium). I'm just not convinced that torsional flex is a big contributing factor when it comes to comfort, especially on a mountain bike when you have such large tyres anyway.
@@Cyclingabout I'd argue torsional flex is the biggest factor since you proved that vertical frame flex is not. The act of pedaling is asymmetrical with weight on one leg at a time on each side in an alternating fashion, taking the bike frame out of a plane and hence apply torsion to the frame. You feel the frame's torsional resistance to vibrations transferred through the legs.
As I mentioned in your comment above, we need to take into account the rate of springs in a series. Let's say your frame has 2x more flex at an angle, and the seatpost has half as much. The overall spring rate of the system still calculates out to be less than the softest spring, which is still your seatpost or tyres. Sure, the data might not be as accurate as we'd like (in reference to aero testing), but it's not like the spring rate of the system will miraculously change because the bike is on a slight angle.
The problem with the theory of vertical springs in a perfectly vertical plane is that when you ride a bicycle, your bike is not - probably rarely completely vertically aligned to the ground. That being said, the bicycle is absorbing bumps not as they are in a lab (perfectly vertical), but when the bike is ever so slightly tilted. Also, if you are claiming that because the lab could not show measurable differences, that would fly in the face of your preference for the resonance damping characteristics of carbon frames since it isn't measurable. In fact, the minuscule differences between the resonance damping effects of certain tube designs are added up among millions of vibrations that occur over long timeframes when you are on the bike. Those can be felt by the rider. Those millions of vibrations while the bike is slightly off a vertical plane. Bikes are pedaled, not run by a motor, so you have the motions of balance at play, throwing the bike at an angle while transferring road jarring which I am not so sure the science has tested for.
Interesting idea, there probably is a little more vertical frame deflection at an angle. I wonder how we could test the theory? My personal experience is that the vast majority of the time I'm going in a straight line, so I suspect the lab testing is quite accurate for the most part. But still, we need to take into account the rate of springs in a series. Let's say your frame has 2x more flex at an angle, and the seatpost has half as much. The overall spring rate of the system still calculates out to be less than the softest spring, which is still your seatpost or tyres.
@@Cyclingabout I think they should put strain gauges and accelerometers (or whatever instruments they use) on bikes (or on the bottom of shoes and saddles?) ridden outside on all surfaces - keeping the same components for control perhaps. It would be expensive I think. I believe that your current experiences is riding a bike meant to take a large load and not break, so the torsion of the bike frame is irrelevant, since it has been made to be as strong as possible. Therefore, you are feeling the bike through the saddle , seatpost, wheels and most importantly, tires. Plus, all that weight resists the upward motion of the road surface, forcing the tires to do more of the work of bump absorption. True what you say about the softest spring being the tires, but this still has significant results in feel. Many springs of different spring rates are not the same as one spring equal to the softest of that of the series of aforementioned springs. If that were so, progressive springs wouldn't exist - they'd all be linear.
But let's be real here, this kind of force/stress testing needs to be performed in the normal axes so that a benchmark for the measurement values can be easily established for different frames and thus validating the comparison because the test parameters are all the same. It is very hard to simulate all the tilts and bumps in real world because they are random even if you tested it on the same track. But theoretically those can be calculated if the forces in reference axes (normal axes) are known. It is easier to calculate for metal frames because metal is isotropic, but a lot harder for carbon if the carbon layups aren't known. @CYCLINGABOUT Thanks for the video. I also think this topic about "frame material ride quality" especially the "steel is comfy" is overblown. Carbon can be made to be stiff in one direction and flex in other direction, thus it is very possible to design a carbon frame that takes vertical compliance into account. In my opinion, the components that have direct contact with the rider's body (other than tires) affect the ride comfort/quality more; so seatpost, saddle and handlebar. People have been talking about "I converted from carbon to steel and it's more comfortable" but they basically singled all aspects about the bike into one "steel vs carbon", thus ignoring other factors. Funnily enough, those who think there are significant differences between frame materials don't have data and almost always only provide anecdotal evidences.
@@sirchristophermcfarlane9377 If there was no study on the topic, then people's conclusions are not true? Does this mean that only where there is a study can there be fact?
@@SurpriseMeJT by "people" which one did you mean? The ones who say that frame materials make a big difference or the ones who tested these frames and concluded that there was no big difference? If you're talking about the latter, then technically their conclusion is true until proven otherwise. And yes, since fact must be proven with certainty and/or observed, they do require study to be established as a fact.
pure worthy content without any bloat! What a simple cure for today's overabundance of drivel and hot air just to be heard. Keep it up because the point is sharp.
I have owned both steel and aluminum road race bikes for years. My personal experience has always been on the same tire size, same routes, same rides. And steel never beats up my body as much as aluminum does. The fatigue from riding on aluminum has always been more noticeable, fatigue from riding steel is non existent.
Expensive heat-treated steel is stronger and can be made thinner to flex more without breaking. Cheap steel bikes cannot do this and feel terrible. It's all to do with young's modulus. Aluminium frames cannot tolerate as much flex. I can littery feel a steel frame flex when I put on the power, so it is very noticeable to us humans. Never got the same flex as put on power from carbon or Ali, so something is making a difference, even if your measurements do not pick it up? I have ridden high-quality low weight Ali frames and they are not the same. They deliver the power more efficiently but also lack feel and spring (both in power delivery and comfort compared to an expensive steel frame). I would suggest it's the way a steel frame flexes, or how much it is able to flex. Perhaps the tests need to look more into real-world conditions - not just flex for a given once only load. Of course, tyres and post make a difference too.
The data suggests that any noticeable vertical deflection difference between frame materials is just a placebo. But honestly, if you think it gives you the edge, that's great! The placebo effect is a very good tool if you can use it to your advantage. 💪🏼
The video discusses vertical compliance which adds to comfort. The 'mushy' feeling you get when putting power through a flexible frame would be the side to side compliance. If you put down a lot of power at a stop on on a cheap bike frame, you can see the bottom bracket flexing from side to side. Due to the triangle shape discussed in the video, despite this side to side flex, there is very little vertical compliance
@@aarontasker6423 I recall a professional reviewer talk about it like a spring, it saves energy for when you get back on it. Some bikes are designed with it built-in. It's a nice feature, and when the amount of it suits your ride it's amazing the flow and zest it adds. Frames I have had that have this power spring have been some of the best tracking frames I have owned :)
@@andrewnorris5415 If it all comes down to Young's Modulus, then why can you feel steel flex (190-215 GPa modulus) but you can't feel aluminum flex (69 GPa modulus)? At the end of the day, aluminum's modulus AND yield points are much lower, making it more flexible than steel. While things like tube geometry do come into play, you cannot cheat the metallurgy.
My most favorite mountain bikes I've owned were cro-mo and they both rode smooth and beautiful but after watching this video now i believe it was more to do with the geometry than anything else. Both of the Steel bikes fit me perfectly but all the alloy frames I've had a shorter top tube for a similar seat tube. I have a carbon seat post in my steel bike now and when i checked bugger its got a fair bit of flex. So now I think a carbon post and good geometry are more important that light weight materials.
CroMoly is an amazing material. It is so strong in the ways you want a bike frame to be, you can get away with ridiculous thinness if built intelligently.
Thanks for this. Always wondered at what point frame material made no difference. 40mm tyres seems that point for yourself, interesting to know. (I'm riding aluminium frame, 35mm tyres, redshift suspension stem, redshift suspension seat post (recent addition))
I too have the Redshift combo on an Alu DBack Haanjo, but with the Rene Hearse (compass cycles) 48mm Switchback Hill 650b's . The rear is on a 25mm int width rim, the front is on a 40mm wide that expands the tire to 56mm. Topped off with a Brooks b17 (w/cutout) and Tasis Fat Tape on top of some fizik bar gel. Not for everyone I know, and not wining any Tuesday Night World Champs., but it rides like a Lincoln Town Car, and keeps this 240 lb, 51 year old out there on the bike.
Very informative regarding frame comfort! I'd be interested to see a comparison in fork materials as that relates to comfort (aluminum vs. carbon vs. titanium vs. hi-tensile steel vs. chromo steel). My guess is that a chromo steel or carbon fork will be more comfortable than an aluminum fork, assuming constant handlebars and thin tires.
Aluminium forks are even more more overbuilt than aluminium frames. And cheap bonded Aluminium steerer/carbon blade are SO very heavy and overbuilt. This is because fork failures = death and lawsuits so you don't take chances there. In comparison a broken BB shell is no big deal.
It's still going to be a carbon fiber fork no matter how overbuilt that will be the most comfortable. As far as weight goes as long as it has at least an aluminum alloy steering tube It's also going to be lighter. A carbon fiber fork is going to be stiffer and have the best steering response. As much as I like my Lemond Zurich 853 steel frame. I can't ever see putting a steel fork in it. The very first thing that I would notice is the handling will change. Not for the better either. There isn't enough rake in a steel fork in a road bike to gain any comfort factor because the internal dampening of carbon fiber is well beyond steel. That can be said about the handle bars, stem and seat post. Carbon fiber as a material is so engineeriable that it would be difficult to shape metallic materials to compete. The only exception I can think of is old school rims . The flat light weight box section tubular rim has alot of vertical compliance. Relatively many thin double butted stainless steel spokes go a long way to provide thst. The front wheel having rim brakes and dishless can be incredibly strong and laterally stiff. Just don't hit an immovable object with it., as it will catastrophically fail. A heaver rim with more spokes in back will round out the ride. Alloy nipples will shave noticeable mass where it counts at no penalties. Except for salt loaded winter streets and the spokes were cut long enough. Obviously I don't care about aerodynamics any more. But I really like 28 mm tubulars . Ironically easier to obtain these days with better flat resistance. Put a nice riding sticky one on front and one that resists flat and wears longer. 😊
To me, vertical deflection is a small and only one component of comfort and road feel. When you pedal hard, the energy goes into twisting the frame and your body is working against it. If the road vibrations are transmitted to your body in the process (at contact points) your will fatigue faster and not enjoy the activity as much. If you are climbing out of the saddle and the frame flexes back a little it is more comfortable and fun even though it may not be as efficient. Same goes for tires:many other considerations such as how well it grips under high speed cornering or how supple the sidewall is under angular forces, determine how comfortable and fun it is to ride.
You make a very important observation here. Not only the pedaling but also the bumps from the road/trail surface and the forces the rider applies on the handlebars all contribute to lateral twisting / flex that is usually deemed undesirable today (hence a lot of frame and component development over recent decades has been targeted at eliminating/reducing this type of flex) We end up with very stiff components and frames by design, that are then compensated for with larger vol tires and suspensions (front, back, seat tube, saddle). Thus it is not surprising that these components become way more important than the frame for comfort. That is how bikes have been designed towards.
After an hour on an aluminum frame, I'm ready to be done. That doesn't happen with steel, carbon, or Ti. Dropping tires to 30 psi didn't change this. This is my experience, not a theory.
From my experience it is mostly about the fork, it the front is a steel fork it is very likely to have a bit more flexibility than a aluminium one or a carbon one, especially if it has more rake. That puts less harsh impacts on the shoulders and makes rides more comfy. The variations of stiffness of the rear is not significantly different. Everyone who changed from a undamped mountainbike to a front shock absorbed bike in the 1990's can understand that.
You're looking at a short lever inserted into a long truss (seat-post into seat tube), the point you're missing here is on the other side of the frame. The long lever inserted into the short truss member (the fork into the head tube). The majority of deflection and bump attenuation is going to occur at the front of the bike. The fork reacts to a bump (regardless of the fork material) and transfers this up to the head tube. There's much more force at this location because of the long lever (the fork), the way the head-tube takes this deflection and transfers it through the frame is going to play a big part in ride feel and quality. Its a simple matter of material science that aluminum has a more tightly packed structure (google images of aluminum structure and steel). Steel has a much looser packed structure and will in fact allow vibrations to smooth out through the material. These micro vibrations make all the difference.
Exactly how i felt after watching this in 2024. I will never buy an aluminum fork again. Carbon and steel forks only for me. Bikes with 2 inch or wider tires are comfy enough for me to tolerate an aluminim fork with minimal complaints on comfort.
People don't really know about modern stainless since it's rather rare to see stainless frames, but modern quad-butted stainless frames are barely any heavier than titanium and same ride quality as typical steel. No corrosion issues or chipped paint, and you can polish the frame up easily with steel wool. I'll never ride anything other than steel or titanium again, went through 3 aluminum frames and they were all horrible. Snagged a stainless Vaya Travel frameset in 2015 and it'll likely be the last frame I own, I love it, and already put thousands of miles on it all over the US and AUS
But are you comparing pure samples or mixed? Usually aluminum bikes use carbon forks as do many steel frames use carbon forks and many metallic frames will have carbon rear chain stays and/or seat stays.
Totally agree, I always laughed a 'Frame Ride' reviews, when what the 'Princes & the Pea" reviewers were actually telling you about were the stock speced tires.
It's cool to see some websites using control tyres for their tests (eg. CyclingTips). I'd love to see them go a step further and use control seatposts, but even that gets a bit tricky with varying seatpost lengths, different seatpost shapes (aero, proprietory) and diameters. Then again, where do you draw the line in terms of describing comfort? Control handlebars, bar tape, saddles?
I don't understand the bike reviews of the parts since you can change all of them very easily. Some parts you should change to make the bike fit better (saddle, stem, handlebar, grips). It's the frame that matters. But if you think that reviewing "Ride" is useless then where do we need any reviews? Let's just watch bike commercials.
@@Cyclingabout it's funny you say that, because while your mechanical analysis is spot-on, my thought during the video was "vertical compliance is a funny way to define 'ride comfort'". My experiences certainly match your data, that tires dominate vertical compliance, but when I think about what bike produces the "most comfortable" ride, I'm not just thinking of how jarring the ride is, but also how much the frame flexes laterally under load, how sensitive the steering is, and how hard I have to work to make it go (I would describe high rolling resistance as uncomfortable).
@@natbarmore "Comfort" can certainly be interpreted in many ways, and with all of the variables, almost everyone will have a slightly different take. Thanks for sharing yours! I think there is a lot of merit to measuring force vertically. Have you ever ridden a full suspension bike? It's pretty hard to ride one (with a high or low lateral frame stiffness) on a trail and not feel comfortable. I've also found that I can make my laterally compliant steel bikes "uncomfortable" to ride by using firmer saddles, stiffer seatposts, and higher tyre pressures. And my stiff aluminium race bikes "comfortable" with more padded saddles, flex carbon seatposts and lower tyre pressures. As a result, I tend to think lateral frame stiffness falls into the 'ride feel' category, rather than the 'ride comfort' category. But then again, I think there's a case to be made that when mountain biking on rocky sections of trail, that a frame with less lateral stiffness will be more comfortable due to the additional off-axis directions of force!
@@Cyclingabout all good points. I've test-ridden full-suspension bikes-particularly liked a Softride with suspension beam (instead of seatpost) and suspension stem. Rolled up a curb and didn't even notice. But I don't ride off-road, really-gravel roads and paths sometimes, but nothing that merits a mountain bike or similar. So I'm talking strictly comparing the comfort on various sorts of surfaces that might be loosely called "roads" or "paths", where the handling obstacles are potholes, curbs, broken glass, and cars, rather than roots and rocks and tight switchbacks.
I had low spec steel framed Specialized MTB with no suspension fork back in the early 90's which gave a lovely, quite flexy, smooth ride compared to something similar in aluminium. I don't think it was my imagination..........
Did some jumps with a steel MTB. Full steel. Not as terrible on landing as I thought. I think its all simply the fork. I mean. Look at the shape, it's usually slightly bend at the bottom, modern forks ain't made that way
This is horse dung. Diameter of tubes, length of tubes, wall thickness of tubes, shape of tubes, butting of tubes, elastic properties of the material, and construction design of the frame all contribute to the ride quality of the frame. High strength butted steel tubes are highly fatigue resistant are much smaller diameter as so flex more, butting of tubes stops vibrations.
@@jamesward3567 Quite, but not so much because I have found what I want to ride, at 75 don;t have much riding left. If I am lucky I may wear out the new tyres on my two bikes but I am not betting on it. Many years working as an mechanical engineer that stuff was my work.
I have many steel bikes and they are smooth riding. Get on an aluminum frame and it feels like it is jarring me to death after steel or carbon. I still have aluminum frames but they have shocks or carbon forks. Otherwise 😮
Very cool! I think something to take into account that isn’t talked about in the video is that often times aluminum or carbon frames have oversized (diameter) seat post where is steel frames often have 27.2 or smaller diameter posts. Obviously the narrower seat post will deflect more and while this doesn’t necessarily make steel more compliant then aluminum, our perception of it while riding is that it is more compliant.
Good info. I find that I change body position significantly if on rougher terrain. It is easier for me to absorb rough terrain on my gravel bike than my "cruiser", but also tires me out (pun intended) faster on my gravel bike.
As an experiment, if you can zip tie one or two 5 lb. hand weights to a bottle cage, the ride comfort improves favorably. BTW, this video is the most accurate ride analysis ever made on YT.
I'm always surprised by all these fancy looking plots the industry shows. Wouldn't you need a bode diagram that shows the amplification of movement of a frame at different frequencies? Also, carbon might sound dull as it dampens in opposing directions. However, the young's modulus of carbon fibre is a lot bigger that steel's and therefore it won't flex at all, stressed in its direction. Quite difficult to reduce this to a "dull sound"
Very strong position using sound principles in mechanics. Would be interesting to hear how the opposing view would refute this strong data. Thanks for the video!
@MJD Exactly,all frames are built differently,to say they are all the same and ride the same........its a strong viewpoint for sure. Seat stays can flex,chain stays can flex,forks can flex quite a bit and it can be seen while your riding. Fork is part of frame.
Very Cool. So based on their numbers, steel dampens vibrations ten times better than Aluminum. I think OP is forgetting that the ringing when he thumps the steelframe IS the dampening happening, as the whole frame transfers that energy into the air as vibrations, while the stiffer carbon or aluminum frame is transferring all of that energy straight into you!
The vibration attenuation on a bicycle is much more than a frame. Your body will absorb some, but so will your luggage/tyres/seat/carbon seatpost etc. The more components with high damping properties, the smoother your bike will feel. I've personally noticed that with 40mm tyres I cannot notice a difference in frame materials. And when I put my bikepacking bags onto my road bike, I think I'd struggle to notice the difference between frame material there too. Anyway, hoping to make a video on this topic with all the data available. 😎
@@Cyclingabout I would tend to agree. With any fatty tires or springy seatposts like that, any differences in frame material would be overwhelmed by the large squishy tires or suspension seatposts, but I definitely DID notice the difference on my roadbike with 28mm Gatorskins when I replaced the frame. If you insist on constraining your analysis, you are technically correct.
Hey there, really interesting video. I have some thoughts… when I ride over rough stuff I usually stand up which in turn means we have to consider a couple of factors not considers it your video that ant that might or might not put a bigger emphasis on the differences on materials. when I stand Seat post and saddle have no influence putting more emphasis on frames and add Cranks to the picture. Definitely handle bars are a massive factor in the feel of a bike as well as grips. Usually peoples hands are more sensitive than their butts. more and more carbon frames are not built in classic double diamond design but other shapes that are not possible in metal that allow extra compliance. Geo, the shorter a bike, the more upright you sit the more the discs in your spine get tortured... so much more factors that could be considered... also when on the seat and pedaling, pressing down a pedal means taking weight of the seat. hence totally changing your stack of springs. the more power I put in the less weight on the seat. in this case only tire and frame compliance can give you added traction climbing up a steep gravel road. Well, the reality is really there is nothing else in this world that people ride around on that people would consider better without suspension or that even still exists without suspension but still some cyclists insist.... only reason we have super uncomfortable road bikes today is UCI rules and bike companies complying to them. How many people really rides in UCI races? Not only does this give us really uncomfortable road bikes, UCI also makes sizing really inappropriate for taller riders as there is max measurement... well, Ok sure Forklifts also dont have suspension, so all of the fork lift drivers out there, your are good to continue on your hardtails
@Fight Film What about horizontal compliance/springiness? Double butted heat treated steel seems to have more springy horizontal compliance without being too noodly which reduces back pain and gives the feeling of so called ride flow similarto therapeutic horse riding. In my experience budget grade aluminium frames were harsh and clunky regardless of tire pressures while also having high speed shimmy on descents.
But is vertical compliance really all to take in account? Could it be that loads from the side on uneven surfaces affect comfort as well? A steel frame with thin seat stays will react different to forces by roots, tracklines or stones than a stiff oversized aluminum or carbon rear end?
Good video. Good to watch. But you are over simplifying this. This n/mm is just one aspect of the equation. And you only examined one direction, but frames are working in 3D. The other thing is resonance, you can feel the difference. Just because you do not feel it, does not mean that other people can not. I have a numbnes problem in various body parts unfortunately, and there is a big difference between frame materials, numbnes comes much earlier on an aluminum frame. Btw I am engineer.
Totally. I like fast downhills,some are rough. My carbon roubaix can and will catch air off bumps,bumps steer it.. My steel frame roadbike sticks to the road and turns on a dime.
But the one direction that was tested in the lab totally makes sense because in reality it is the direction where most of the force comes from during a ride and also the first contact points. Sure, he is oversimplifying it but it is a less than 10 minutes video. I would appreciate more if he also includes the basic theories of the physics, the test methodology, environment, setup etc, but it would take too long and people would be bored to death. Now the thing is that, this vertical force is measured and can be used as reference, so say you want to calculate the force acting at a certain angle, you can derive it from the reference. Metal is isotropic so theoretically if you have the frame dimensions etc you could calculate the forces acting from another directions. However, as said in the video, the vertical flex of frames is very small, so assuming that the frame will flex more (thus "contributing" to ride comfort) in another direction makes no sense except if it was designed that way. Your numbness problem could be caused by so many reasons; different frame geometry, riding position, your body condition, thickness of bar tape, the saddle, seatpost, tire pressure, road condition, speed at that time, etc.
Also didn’t say much about feel through the pedals. Seat feel is of course important, but road buzz through the pedals also affects road feel. Also, all things equal, a heavier bike will always feel smoother than a light one. Maybe steel feels more comfortable partly because it’s mass is greater and it takes more force for a hit to move the frame against the rider contact points.
Carbon is different for every bike, it can dampen vibration really good, or it can rattle your bones to death, it just depends on how the fiber is wrapped. Steel can be just as light as aluminum, especially stainless. Modern steel has come a long way. They simply use modern alloys that require far thinner tubes, then quad butt the ends to get enough material at the weld points. A properly built stainless frame should weight roughly the same as titanium. Look at SpaceX and Tesla deciding to use a new stainless alloy to build the Starship and Cybertruck. A few years back nobody would've ever thought steel would be a good idea in a rocket lol
Presentation is nice and simple, but the good engineers out there are all thinking the same thing "Dunning Kruger effect at work here" ...... Let the misinformation continue.
Tire width and pressure always supersedes frame material, but one should not discount the latter. I had a 2010 Jamis Supernova and a Lemond Tourmalet 853 steel. The former ran 32mm knobbies and the latter ran 25mm slicks. Both were very comfortable. I once made the mistake of using the 25mm wheelset on the Jamis. It was so uncomfortable I couldn't sit down for more than 5 seconds!
I bought a very expensive Ti frame and it’s amazing how smooth it is. I think you forgot to consider how much it helps if you riding on a cloud of hundreds. 😉
vibration dampeners usually work with tuned mass between flexible parts. steel frame may not flex any more, but it is just the weight of it that acts as a damper between the tires and seatpost flex. So it's not just placebo, it's the weight of it. also the example of harsh bike has very tall triangles. so it has no flex. with BMX style frame at very low triangle it flexes more.
Thanks for the effort making this video.I have both steel and aluminium frames hardtail and I cannot tell the different, but have always thought I am not good enough to feel the different. The video pretty much explains well for vertical compliance. I bet there will be huge arguments over whether this is true or not in the comment section. Though, it's good that we keep thinking, making more connection in your brains.
This came up on my feed, and based on recent experience, I concur. I'll explain. For many years (38 to be exact), I've had a Marukin M420 road bike. I recently had it overhauled by my LBS, which put on 27x1 1/4" Panaracer Pacela ProTite tires on it. ProTite is Panaracer's puncture protection system; it's implemented by an extra band of material between the tire tread and the carcass. Because of the ProTite protection, the tire has a rougher ride. I feel almost all road imperfections, including the individual stones in the pavement. OTOH, same LBS had a vintage Cannondale ST500, which I purchased and had overhauled. However, because it has an Al frame, the LBS put on regular Panaracer Pacelas; they're the same 27x1 1/4" size as well. The regular Pacela doesn't have the ProTite puncture protection, so it offers a much more supple ride. The Cannondale, in spite of having an aluminum frame, rides MUCH BETTER than my Marukin does! The main difference is one of the spring force variables cited in this video, mainly the tires. Years Ago, I rode a bike with an aluminum frame, and it was stiff and jarring. The bike had a suspended seatpost. However, I don't know what tires the aluminum bike had. I can't explain why the aluminum bike I tried out had a harsh ride. OTOH, based on my recent experience with my two road bikes, both of similar vintage (mid-late 1980s) and their different frame materials, my Cannondale rides much better; the only major difference between the two (besides frame materials) is the tires that each uses. The aluminum Cannondale, with better riding tires, rides better. Thanks to this video, I now know why. THANK YOU!
Nice. Seems like shock absorption is all about tires and suspension. However the frame contributes to dampness. I can definitely feel the differences in materials. Steel has a characteristic feel compared to Aluminum. A carbon Bianchi with countervail is super smooth!
I feel like you're reading my mind because I've come to the exact same conclusions over the last couple of years, and have been meaning to write an article for a while. I always try to explain this to people, but they don't understand because they've tried x aluminum bike and thought it was stiff and y steel bike and thought it was comfortable, yet they haven't controlled for tires, tire pressure, seatpost length, saddle, fork, handlebar, etc etc. Or too stuck in the "steel is real" thing, thinking that steel has some magical quality that allows vertical compliance, when in reality it is the stiffest material used for frames (and also damps vibrations the least, iirc?). Not that steel doesn't have other benefits. You might look into framebuilder Rob English (English Cycles). He has a masters in mechanical engineering. Despite using the thinnest seatstays in the business, he also says that frame vertical compliance is a myth and thus designs to maximize seatpost length. The single exception to all this are vintage rim-brake steel forks with thin walls (this does NOT include most unicrown forks e.g. Surly-type bikes, and it doesn't even include many lugged crown forks). Aluminum can't be made to flex enough in a fork due to fatigue.
I'm glad we're on the same wavelength! Rob English's work has come up in my research for my next video, and I read a very similar statement he made about his 'pencil' stays.
@@digbysirchickentf2315 It's not just tube diameter but also tube wall thickness, and I think wall thickness varies a lot for steel frames and forks. Not sure about aluminum. If you get a stock steel bike, especially one designed for touring, it's gonna have fairly thick walls (although touring bikes have long chainstays, which means long wheelbase, which probably adds a lot of comfort). If you get a custom steel bike where the builder knows your weight and uses tubes no stronger than necessary, it's going to flex more than stock steel. But like this video correctly points out, tires matter way more than anything else.
@@flt528 top end steel frames(the same can be also said for aluminum as well) use tubing from a stronger alloy and/or heat treating. This allows a lighter walled tubing to be used which will be flexier assuming comparable wall thickness. That said frame rigidity is largely overrated. Most of the hype of the stiffer is good way of thinking is due to marketing. A few decades ago it was all the rage with thin walled Reynolds 753 and Tange prestige tubed frames with how it was so compliant and comfortable.
@@flt528 of course high quality bike frames are made of thin walled tubes. Try study triple butted tubing... The reason for large diameter Alu tubes are (...were) compensating light thin walled tubes with strength through larger diameter. Danish Principia were head of the game in that development...
Excellent analysis on vertical compliance. Though I'm curious why you didn't consider fork, stem, and handlebars? IME, the bumps coming up through my hands have a much bigger impact on my discomfort than anything coming through the back end. (I have a sprung Brooks saddle and a Softride suspension stem on my primary bike, and when I ride a different bike, it's the stem I miss the most.)
I understand the video is about frames but I think the idea of steel=comfort always came from curved steel forks that were designed to flex. Also there are some steel bikes (don't know off the top of my head) which have specially shaped rear triangles in an attempt to allow the tubes to bend, which would allow an action similar to mountain bike rear shocks. Not common, but worth looking into as they are a definite exception. overall a nice video.
In theory the steel blades flex a bit more. On practice especially a road bike. There isn't really enough rake in the fork to take advantage of it. It needs to happen as near to the hub as possible. Any flexibility in the blades near the crown is felt in handling. And that part also needs to be the strongest. I'm not saying it is not possible to make a nice steel fork. But it's expensive. High quality steel is essential. Complex forming of the tubes is essential. And then it takes experience to bend them and put it together. At the end you have an expensive fork that weights more than Carbon Fiber. There may be the same vertical compliance, but the lateral compliance ( lack of stiffness) in steel will be greater and undesirable. And the Carbon Fiber fork will definitely have better internal dampening. I believe the old school rims had a much bigger factor in ride comfort.
A quick question on vibration attenuation You stated in the video that on bikes with narrow tyres and no luggage, you prefer carbon fibre bikes as 'carbon kills the road buzz' You also stated that vertical compliance between steel vs carbon frames factors very little when taking into account springs in a series. Hence carbon is more comfortable without any noticeable differences in frame vertical compliance Are there any vibration attenuation differences between nice steel vs cheap aluminium which may result in the comfort which some purport? (on bikes with thin tyres and no luggage) Otherwise I really enjoyed the video, thank you for taking the time to make this
There are undoubtedly differences between a cheap aluminium frame and a nice steel one when you run narrow tyres and no luggage. I couldn't find any strong data on the matter, but my personal experience is that 40mm+ tyres are damping very large proportions of vibrations from the road, so that is probably where I wouldn't notice a difference between a cheap aluminium frame and a fancy steel one.
@@Cyclingabout I 100% agree with you on the frame having minimal difference with large tyres etc. I believe that the belief of steel being more comfortable would have originated in the 70s and 80s where mountain biking was not too popular and road bikes would often run 18mm tyres. Vibration attenuation would therefore be very important when it comes to absorbing the road buzz Whilst not on bicycle frames, this paper found that the vibration attenuation (damping ratio) of steel is almost double that of aluminium www.sciencedirect.com/science/article/pii/S1877705816302284 I can imagine therefore on road bikes running skinny tyres, you could definitely state that steel was more comfortable than aluminium due to these properties
I agree that steel bikes ride smoother when comparing bikes with narrow tyres. And yep, I'd say the rock-hard 18mm tyres and 'square' steel frame weren't doing much for ride comfort back in the day. 😂
I still feel like the narrower tubing in steel and titanium does less to transfer "road buzz" to my body than aluminum and carbon. And the sharp, brief "tink" you get when tapping alu/carb., as opposed to the ring of steel is actually an indicator that the steel moves more, vibrates, than does the former, not less. That longer ring is an attenuation of the force applied to it, smoothing out the buzz. For bigger bumps this may not have the same effect, which is what all your data was measuring. That said I'll definitely be investing in a good seat post. Do you have a favorite? I'm about to purchase a Surly Ogre and will be kitting it out soon. Great videos, I've watched a bunch of them recently. Well done.
Thanks for the vid and the all work you clearly put into it. Bike designer Mike Burroughs (r&d for Giant for many years) mentions in his excellent book 'Bicycle Design' that there is no inherent difference in terms of rigidity between the two materials, but because steel is stronger you are able to use narrower tubing allowing a less torsionally rigid frame. Aluminium is weaker so thicker tubing is required leading to a stiffer frame. You also don't need much of an increase in tube thickness to acheive an exponential increase in strength. One would have to build two identical frames with identical geometry, tube diameters, wall thicknesses and subsequent spec to be able to perform a valid comparison. As many have mentioned there are many factors contributing to the flex of a bicycle so presumably you'd need to eliminate all variables save for the frame material. So really you may be right in your title but you'd need to risk building and riding a thin tubed aluminium frame..! Of course, we have carbon now so no need to try :-) Just some thoughts! Cheers
Most mass produced aluminium frames use very thick tube walls, like 1/8" thick AL vs 0.04" CrMo. I think there is some improvement with hydroformed tubes that kind of do what "butted" steel tubes do, but Aluminium fatigue is still huge unknown risk so I don't think you could ever really get that thin. Carbon plastic is indeed the best bet.
I think I mostly agree, but this is looking at vertical compliance at the seatpost - what about at the handlebars? The vertical spring system there is tire-rim-nipple-spoke-axle-hub-fork-stem-handlebar, obviously the tires are still very important, but many steel forks do appear to have pretty substantial compliance even relative to tires and certainly relative to aluminum or carbon forks. Is it possible that the swept steel fork design and its relative compliance explains some of the perceived comfort difference there? I also think it's worth mentioning that steel frames have in somewhat recent years been associated with trends of higher tire clearance and several other comfort-related geometry innovations, since steel is more easily worked on by individual framemakers and also seems to be preferred by the alt-biking/xbiking crowd. So it could also be a correlation between brands like surly or salsa producing highly comfortable steel bikes that allow for things like wider (lower pressure and softer) tires, luggage, etc. and allow for or encourage comfort modifications in the way of saddle or alt handlebar designs too.
Anybody who says 'there is virtually no difference in the virtual compliance of bicycle frames' has apparently never ridden a Trek hybrid bicycle from the early 2000's. I don't give a damn what kind of tires you put on it, it rode like crap.
The placebo effect that you mentioned is mainly due to the flex at the bottom bracket area. Since steel bike will have a cushy feel while pedalling compared to carbon bike, the perceived comfort feeling might be higher.
I've experienced the most increase in comfort with a carbon fork and especially handle bars. Even on thinner tires the dampening is noticeable better, actually most noticeable in regular city riding over badly maintained bike lines or cobblestone streets.
Frames also deflect side to side - with every pedal stroke. You can see it if you look. Chainstays also flex to the side when turning - harder to see but you can feel it. Forks delfect in both plains - you can see it when you stand on the pedals.
Thank you for this video. Excellent analysis. I see some BTL comments are trotting out the mythical difference in feel between common seamed high tensile steel tubing, and thin-wall steel alloys such as chromoly and mangaloy (Reynolds 531, etc). This misses the point you clearly make. Much work has been done by some of cycling's most respected engineers and scientists (as opposed to marketing departments and other sellers of magic pixie dust) to debunk this hokum. Here's the late Prof. D.G. Wilson on the subject: "The goal of increased strength or stiffness is somewhat in conflict with elastic compliance for comfort over bumps. Actually the main arena for this competition is the handlebars, and to a lesser extent the seat, cranks, and fork; the rest of the frame plays no role in softening bumps. There is probably value in trying to increase the handlebars’ torsional stiffness while maintaining or decreasing vertical stiffness." (David Gordon Wilson, Bicycling Science, 3rd ed. MIT, 2004, p. 367). Further : "In Papadopoulos’s limited experience of blind testing (varied tire pressure +/- 1 bar, varied bicycle mass +/- 2 kg) or double-blind testing (varied frame stiffness and material) of bicycle characteristics, riders could not demonstrate anywhere near the powers of discrimination among alternatives that they claim to possess. We speculate that many ‘performance’ sensations are imagined; demonstrating otherwise is a promising field for determining what really matters." (p. 302). Finally: "David Malicky (1987) performed a double-blind test of stiffness perception, using bicycles with frame tubing of relatively high and relatively low wall thickness (with mass added so the bicycles would weigh the same). The test population of racers could not perceive any difference in stiffness among the bicycles. (p. 367-8). Sorry for the long comment, but as a cycle industry veteran, this is a subject close to my heart.
I hadn't seen some of those names before. Interesting stuff! If you're into podcasts, check out the Marginal Gains podcast on cycling placebos... I think you'll like it: marginalgainspodcast.cc/the-placebo-effect-and-marginal-gains/
would a full suspension Mountain Bike be far more comfortable for long touring rides, given how front and back are suspension and how they have wider tyres ?
Suspension and wide tyres would indeed smooth bumps. Though full suspension would require carefull adjusting: If rear suspension is any too soft it will move from force of pedalling wasting power. Also full suspension adds more parts to wear/need maintenance. Wider tyres wouldn't make difference to that and suspension seat post would be simpler to maintain compared to suspension in frame.
7:50 "But on my bikes with narrower tires, I've always preferred the way carbon kills the road buzz." So this "myth busting" video doesn't apply to bikes in the race/endurance below 40cc tire categories, where frame materials/design matter. You missed differences in fork compliance, fork rake, head tube angle, fork materials/layout. Major oversight! Many aluminum bikes use carbon forks. Most uncomfortable bike I've ever ridden is aluminum. I still have it, and it still rattles out my fillings when I ride it. This is largely due to the steel fork, but also due to dropped seat stays and bad geometry circa 2000. All aluminum bikes are not created equal.
Yeah, the race/endurance bikes are where you'll notice a difference in terms of vibration attenuation. I didn't cover the front end of a bike, because the head tube has virtually zero vertical deflection. I might cover the topic of fork comfort at a later stage.
Front end matters a lot more than rear seat stay compliance. Fork is the first point of contact for bumps + vibrations + bucking sensation. Head tube doesn't deflect much, but head angle and how top/down tubes attach certainly matters. A well designed front end deflects 3X more than rear. www.sheldonbrown.com/rinard/rinard_frametest.html Also, different frame sizes on same bike model change stiffness. Crazy to think that about 10 years ago bike manufacturers were all competing to make their bikes more stiff.
I agree that the front end is incredibly important for comfort. But that's a topic for another day. Frame size plays a very small role when we calculate out the springs in a series - as I stated in the video, the overall spring rate is ALWAYS less than the softest spring - usually the tyres, sometimes the seatpost.
@@Cyclingabout "Frame size plays a very small role" = another oversimplification. An XS frame can ride a lot stiffer than XL on same bike model. That's why, in recent years, many bike companies have spent so much extra money $$$ on engineering and manufacturing expensive molds/layouts for each size with same parts.
That's incorrect. I've already explained why the vertical deflection does not change. Manufacturers change the moulds because riders of different heights and weights require different carbon layups to optimise the frame stiffness and strength.
I have a canyon endurance with flex seatpost.... but when it bends it changes the angle of the saddle..... I had problems with that, so I have a normal again now.... om my road bike that is but the 30mil tubeless tires give me a lot of comfort :) and for my bikepacking vacations I orderd a santos crosslite with 50mm tires and rohloff/gates system hope to get it in 5-6weeks :) for my iceland trip this summer if I can go ad least
With flex posts, I've always accounted for the saddle angle by tipping the nose forward when no load is applied. But currently I'm using and loving the eeSilk post which stays flat as it goes through its travel - and I've been able to tune the spring rate to the level I prefer! Congrats on the new bike! If you haven't used the Rohloff/Gates combo before, you're going to absolutely love it.
Confort=spring force? I think some other variable need to be add to conclude, your feet and your hand are on the bike too. Its not just a seat post thing
This video is about the role a frame plays in the overall bike comfort. Hand comfort is a function mostly of your handlebars and grip choice, but also the fork, depending on the terrain. Foot comfort... well, it's probably your shoes don't you think?
With this video we went waaay deep into the rabbit hole of geeky, in-depth analysis... I love it! Well done! It's been a long time, after many years of following bike tech, that I've actually learned something new! Interesting subject and approach!
@@Cyclingabout question: Canyon now offers a flexing seat tube (e.g. on their endurance model), as a road racer should I consider this or definitely stick with the rigid seat tube?
@@JanTrenson For a road bike, it kinda depends on your riding style and what you prefer. I personally have a flex seatpost on my race bike and think it's beneficial. If you've ever dug into the "hysteresis losses of tyres" you'll know that lower tyre pressures can actually be faster when a surface has imperfections. (*Warning: the next section is extra-nerdy and currently theoretical because I don’t think people are testing this*) That’s because the losses in the tyre sidewall/casing dominate until the "breakpoint pressure”, when then the "impedance losses" start to dominate. Adding a soft spring to the series (eg. flex seatpost) theoretically allows us to increase our tyre pressure past the usual breakpoint pressure, reducing the impedance losses in the system, and decreasing the overall rolling resistance. Basically, if our understanding of "impedance losses" is correct, I think the fastest system has to be the one with vertical compliance built into the handlebars and seatpost. You can read more about rolling resistance and “impedance” here: blog.silca.cc/part-4b-rolling-resistance-and-impedance
@@JanTrenson Oh, and careful with the Canyon flex seatposts, they're particularly soft! You can see the seatpost data here: www.cyclingabout.com/seatposts-overlooked-yet-critical-for-cycling-comfort/
When I was young (17) I had a race bike with a Colnago frame made of Columbus Zeta steel tube (plus, as a side note, the first aerodynmic Dura Ace bike component set wih excentric pedals as a side, which was bloody expense for me at that time). My brother had a much cheaper bike with a much stiffer frame. Compared to riding my Columbus Zeta frame his bike felt as unforgiving as riding on a brick. I could feel this particularly when doing turns. My bike felt like it would snuggle into the curve radius. The sensation, and difference, was more than just subtle: It was tangible. Of course it all depends on the individual construction of a frame, not just on the material choice. However, steel is more elastic than aluminium, and if you build a steel frame and its tubes right, it will flex more than a similarly robust Aluminium frame. So there is material physics speaking in favor of steel comfort wise, as experience to back this up.
Just installing slightly larger tires and running a lower pressure will have a much more noticeable impact in ride quality that any slight deflection, be it frame, fork or seatpost, may have.
Yep! You can achieve very low n/mm values with voluminous tyres. But keep in mind that not all bikes have the clearance for wide tyres, so the other components should be kept in mind.
I should also clarify this video doesn't address another aspect of steel frames vs. other materials -- namely the differences in vibration-dampening properties: web.mit.edu/2.tha/www/ppt/Bike-ISEA.pdf
@@peterbense5650 I thought this was covered and the answer was "negligible"?. Geometry seems to most important. I have a straight carbon fiber seatpost(SADDLEpost?) and it has NO compliance, naturally. But it looks cool.
I thought steel was standard on touring just because the repairability. I'd be more interested in a video on how many welders can fix aluminum. I heard aluminium is so common a material it is just as likely to find someone to do an emergency repair on a aluminum frame as it is steel. Modern steel bikes use such thin walls I heard it is more difficult for a welder to repair where aluminium tubes are pretty thick and easier for average welders to work with.
The problem here is not the welding per se. Aluminum can be welded, but in order to achieve the desired mechanical properties the whole frame needs to be heat treated afterwards.
My brother held a couple of time trial records for many years and he has had every bike you can think of, but he will always choose a steel frame for long distances which are his speciality, the results speak for themselves over 40 years of competitive cycle racing at a high level, up to Commonwealth Games at one point. He said he might lose time in first half of race but in second half the fatigues sets in on other types of bikes, rider discomfort kicks in
Thank you, I've been saying this to steel snobs for a while. I like steel and ride it regularly, but riding to work there is a section of "cobbles" as well as lots of rail crossings. When riding that section, my aluminum bike shod with 28c tires feels like a featherbed compared to my steel bike with 25c rubber. When people start talking about frame comfort I always say that tires, bar tape and a nice chamois are infinitely more beneficial.
In my personal experience, tire size and pressure trump everything on vertical compliance in road bikes. Riding tubeless now, I can ride at a lower pressure with no performance penalty and dramatically increased comfort and stability.
A few comments: • It isn't just the width of the tyre that makes a difference. Some brands of tyre aren't as compliant as others. Simply changing to a more compliant brand in the same size can make a huge difference. I bought a set of slightly used hand built road wheels from a friend who didn't like them, tried them out and I also hated them for the road buzz, then swapped the Contis they had fitted to some Michelins, and they were perfect. • The choice of tubes can also make a big difference: latex tubes are more compliant than butyl rubber. • Your video ignored the front end of the bike. The road buzz transmitted via the front wheel, forks, and bars into the hands can be a major factor in the perceived (lack of) comfort of a bike. Aluminium and carbon forks go straight from the crown to the dropouts, and the geometry doesn't allow for any give. Steel forks are generally designed with a curve in the blades, which allows the fork blade to flex ever so slightly. On a road bike, with skinny tyres, that fork flex can make a difference.
I totally agree that big tire and carbon seatpost are way more significant impacts in comfort, but over a long distance of riding Give me a choice of steel vs alu frame w/ similar cockpit and tires, I will always choose Steel. Plus When your standing on your pedals over rugged terrain, your seatpost deflection doesn’t matter, and depending on route that matters to more tired legs.
Even if you take the seatpost out of the equation, we still need to calculate out the 'springs in a series'. That's the frame which could be 7000N/mm, the wheel which is 800-1300N/mm and the tyre which is somewhere between 10-250N/mm. As I stated in the video, the overall spring rate is ALWAYS less than the softest spring. You, therefore, won't notice any difference between a steel and aluminium bike in terms of tired legs.
Adding heavy cargo significantly improves comfort. I once carried my big ass bluetooth speaker on the rear rack of my bike and the added 11kg clearly dampened most bumps in the road. It did however make the ride quality much worse, because the high center of gravity is not fun to ride at all. I'm really wondering how a bike rides if you put the full amount of cargo onto the rack that it is allowed for (25kg in my case)
Engineering knowledge highly suggest something. You talk a lot about vertical reflection but we just don't see aluminium reinforced buildings, or bridges made from it. Plus those are tubes - so forces don't work just vertically downwards. What do you mean from comfort? Just butt related? With carbon or aluminium you need to check regularly for signs of breaking, rock chips or dents, corrosion. Look what brake cable can do around aluminium head of frame. That's why most of bikepacking bikes are made of cr-mo steel - you just can leave it outside on the rain (water) next go to the desert (sand dust/rocks/hot), later on winter crap (cold, salt, mud) and you don't give a f. Meantime precious frame made of Easton or Industrial Carbon went to fk itself. That's why it's easy to find 20 years old steel bikes going hard (they made aluminium bikes then) and it's almost non possible to find used 5 year old carbon bike (unless it's in prestine condition with stock brake pads and tires - means non used at all). Nowadays we are used to aluminium or carbon rims, frames to snap. I've seen snapped carbon frame like 2 weeks ago? And last time I've seen cr-mo frame to snap was like 15 years ago on some BMX dirt jump contest after HEAVY crash. Those materials are just for different purposes. I don't mind carbon on road bike, aluminium for xc racing but for daily commute or very long trips - steel is steel ;)
The point is not that frames don't deflect. They do. Maybe some steel frames flex at 4x fewer newtons per mm than other aluminium frames? But whatever the difference is, the vertical deflection of a frame is essentially meaningless when you calculate out the springs in a series - where the softest spring always dominates.
Please read this article: www.sheldonbrown.com/rinard/frame_fatigue_test.htm The design of the frame makes more of a difference than the material. A frame must be designed properly to be strong, light, stiff, etc. The designer needs to choose the appropriate dimensions and structures for each material. Steel bikes don't last forever and yes they can break or crack and repairing them isn't as easy of cheap as people like to make it out to be.
All of us engineers know that deflection is based on a property called Young’s modulus. Steel is three times stiffer than aluminium of the same geometry. But geometry changes stiffness at a cubic rate. And aluminium is three times less dense than steel. Carbon fibre is all over the place depending of strand orientation and compressive or tensile forces. The best choice of all is clearly magnesium, which is why I have a magnesium frame. Happy days
In 2008 I picked up a Lapierre carbon frame and Easton carbon fork and parted over all my components from an aluminum Leader with a carbon fork, all the components were the same, wheels were Mavic Ksyrium, etc, and the ride difference was immediately noticeable. Not only could I feel the difference but you could hear it. The carbon frame has a quiet quality while the aluminum frame resonated into the wheels. No doubt the Alu Leader frame tubing was over sized and made it extra rigid, so was it the material or the tube size differences, IDK, but the carbon frame was an exponentially better ride. Not sure about the carbon long-term though, and starting to think it’s time to retire it
It's annoying I know, but the reason I'm hoping to build a Patreon audience is that TH-cam pays about $10 per 10,000 views! When I put 100+ hours into a video like this my hourly rate is, no joke... 20 cents. 😂 If you think this bike knowledge is worth more than 20c per hour, consider supporting the channel here: www.patreon.com/cyclingabout
Can you put more ads for revenue? I'm quite ignorant regarding the whole monetization of social media.
I find you to be quite knowledgable about bikes. Would love to buy one of your books. Do you do print as well? Also do you have a background to engineering.
Probably a fair rate of pay for such arrant nonsense ;-)
@@glennoc8585 TH-cam keeps putting more and more in while paying out less and less. Many content creators have given up making money from TH-cam.
I agree with your video for the most part, but one caution: comfort is not only about flex, it is also about vibrations. I found carbon to be better at dampening vibrations (trail chatter). I had an alloy Scott Scale, before replacing it with a carbon version. Seat flex was marginally different (I could not really tell was it slightly less or more cause seatposts were almost identical) but the vibrations were way quieter. If you owned two almost identical bikes one after another, with the main difference the frame material, I believe you would have a different experience. I think it is a good example cause both bikes were equipped with almost identical Syncros hardware and wheels (Scott's own indoor brand). And tyres were same size, similar pattern and composition, with me always having identical air pressure.
Great video. I love steel bikes, not just for their supposed comfort, but I agree with everything he said. Tire width and pressure matters far more than anything else for bump absorption.
After a lifetime of futzing with bikes, including working as a mechanic, I think that most of what bike nerds obsess about just doesn't matter (unless you race bicycles to earn a living). The older I get, the less fussy I am about parts, and the more I enjoy just riding.
Being happy riding bikes, that's a great place to be!
But.... steel is the only frame material rhyming with “real”. 🙂🙂
Steel frames are definitely more comfortable in general. By far.
@@FightFilms Exactly.
There's no denying it objectively speaking.
@@FightFilms Put it on a test rig to test vertical compliance and you will see the truth instead of steel is real blaa blaa
real steel was a cool movie ngl
@@SDRIFTERAbdlmounaim I have absolutely ridden bikes that felt like getting punched by a robot.
Something not explored in this video is the frequency range of vibrations; they cover a spectrum depending on road surface and what obstacles you encounter. With similar setup when riding on the roald, I've always had the unmistakable impression that steel damps the higher frequency vibrations better than carbon resulting in a more velveting road feel that I simply haven't experienced on a carbon bike.
Yeah totally agree. Everything dampens different vibration frequencies differently.
I think the cream of the crop for smooth frame materials is bamboo.
I built a bamboo hardtail and it is night and day smoother than any other bike i have ridden
totally agree with this! your body doesn't feel the distance of the deflection, it feels the frequency
@@mog3680 No difference. Those have been measured too.
when people test bikes without being allowed to see the frame material, they no longer can distinguish this kind of stuff. @@mog3680
@@mog3680 i like to cuddle with my bikes naked frame (no components on) and watch videos of the course im going to ride. so i can feel in tune with the frequency of the bike and match the frequency of the road so everything is in harmony. makes the ride so smooth like gliding on a cushion of air. similar to air hockey puck. sooo good
Is the fork considered not part of the frame? On many vintage bikes you can see the fork flex if you pull the front brake and try push the bike forward. How about vibration dampening? Sorry but the seatpost flex test seems too simplistic to paint the whole picture. Youre correct that tyres and saddle etc play a huge role though, not arguing that.
The fork is not a part of the bike frame, the play of the suspension fork is because those old forks are cheap and made without much attention.
I agree. I have two Hardtail MTB frames which I push to the extreme downhill. (Same geo and I use pretty much the same parts on them) I can definitely feel a difference between my steel and alloy frame hardtails. The steel is not only faster but also more comfortable. The tubes are smaller and they also swing and vibrate completely different. He is just talking about but comfortable but not the difference between steel and other materials.
@@Bjoern_the_Baeri think his point is frames dont flex much in comparison to tires and the seatpost that have the most defoemation while riding.
@@richr161 Look at 1:51. the fork plays a major role but he 'conveniently' left it out of the equation because it wouldn't support his message.
I noticed that the fork was ignored too. Maybe that complicated the message too much? Even among my steel road bikes, I can tell that some flex more than others, and a bit of flex does help reduce the vibration that gets to your hands.
Great video, but forgot to introduce the advantage heavier frames have in terms of comfort simply due to higher inertia. It's the same when you attach bottles and bags to your bike--it becomes more comfortable to ride because the bike simply can't rattle you as much as lighter bikes can. This is probably one reason for why people believe steel bikes are more comfortable. They may be, but not if you compensate for the weight difference, for example by attaching weights to a carbon frame.
I totolly agree.
Interesting thought 🤔
I think people mistake the feel for comfort. I find a steel bike feels springy but I wouldn't say it's a more comfortable ride. Hitting a pothole on any roadbike will be jarring.
I clicked on the video with an attitude: “Oh yeah? Change my mind!” Well, thanks for changing my mind! You have a great way of stripping away the hubris and spookiness and bringing science to the forefront. 👏
I did the same but was not convinced.
I'm glad you went and put some numbers and tests to this. The conclusion also feels pretty correct. I changed from a 700 28C to a 29er MTB and the comfort I get from these BIG tyres make much more of the difference, also the seat post and saddle, play in that equation.
I actually started road riding on that EXACT same steel trek (my dad's old bike), then 20ish years ago when I finally bought a modern GURU road bike with aluminum lugs and carbon tubes the difference in stiffness was MASSIVE (the carbon bike had what felt like absolutely zero flex or peddle bob and my feet would go numb from road vibrations...it made the steel trek bike feel like a full suspension bike!). So I'm not sure how much I really agree with the results here, at least my interpretation of them...
Real
Agree. I have a 1983 Peugeot PSV-10 with Super Vitus tubing and it is still the most comfortable ride I have ever had including carbon.
All true of my experience as well, but the video is correct; it's likely to be better geometry and more pliant seatpost/wheels/tyres that do the job so well on those old bikes.
The reason to choose steel is resiliency. I've snapped a steel bike while riding it... it carried on riding, because it bends rather than breaks. I've snapped aluminium and wiped out dangerously, because just like carbon/resin, aluminium fails suddenly and catastrophically. Therefore, steel.
Its almost certainly the differences in GEOMETRY you are feeling, not material.
Also as mentioned in this excellent video: , tire size, tire pressure, tire material, saddle design and positioning, handle bar tape, set post, fork design.
@@j.k.cascade2057 hmm I ran the same tubes and tires and saddle on both bikes. I could see the wheels causing a difference in compliance though. But they were just completely different bikes, night and day difference in stiffness, compliance, power absorption/efficiency...it was noticeable on the first couple of peddle stokes and even more glaring during sprints, the trek would bob like a dual suspension bike.
I've known for a long time that changing your seat post to say carbon, can make a stiff uncomfortable bike less taxing to ride. Thanks to you now I know why.... great video.
Thanks!
I think most of it comes from when aluminium bikes were fairly new. I am old enough to remember. I had a Bridgstone RB1 (a now legendary frame) and I could feel a little bit of flex in the bottom bracket when I'd sprint or stand to climb. In 1991, I bought a new Cannondale and the ride was very different. It was much more harsh, but there was no detectable flex in the bottom bracket. I loved that bike even though the stiff frame combined with the high pressure 18c and 20c tires brought a very jarring ride. Aluminum design has greatly improved since then but the image has not for a lot of people
I loved my Aluminum trackbike. Though it was VERY harsh. I learned to ease on sitting the saddle. So I was mostly on my legs while riding it. Though they are ment to be rigid and to be ridden just a short time.
Read about the differences/development of alloy during time.
Giant did some great work evolving from 70 to 60 Aluminium which gives a smoother ride being more flexible.
roadcyclinguk.com/gear/giant-defy-aluminium-range-overview.html
It comes from normal bikes, not high end bikes. 95% of the bikes out there are cheap. And Aluminium has to be overbuilt to be safe. It's true there have been advances from big manufacturers understanding aluminium better since after the 1990s. But a lot of those 90s bikes are still on the road (which is awesome, bikes are such a great durable vehicle.) And loads of bikes nowadays are still build that way. Aluminium welding and metal fatigue, heat treatment, these are tricky. With steel you can do that in your garage. Most Aluminium is stiffer, even if it is not inherent to the material itself.
Cool. I still have my RB-1 that I bought new many moons ago. Love it . I've squeezed 32 slicks on it and have taken it on MTB trails and loaded it down with touring bags. But getting a gravel bike now that will better suited for those things. A steel one.
I had a Bridgstone MB3 as my graduation present. Sadly, it was stolen. Still my favourite bike of all time.
Thanks for the informative video. You inspired me to buy a Brooks B 67 saddle for my Cube travel bike. I remember how comfortable my English 3 speeds were with their sprung Brooks saddles. After so many years on 23c tires, I am also loving the 2.2's tires. I can run the pressure down to 30 psi and they still roll great and give a soft ride. I have also started running 25c's on my Giant TCR. I guess as I get fatter, so do my tires
I've tried steel, carbon, aluminum, titanium, and looked at trying magnesium alloy. Honestly, I haven't felt a difference outside of the stance, ride position, and tire width. I ride steel now on both my hardtail and my gravel bike. The only reason I do this is price. Steel frames are so much cheaper to find and build, giving me more money to spend where it really counts. I'm not a weight weenie, I would rather have a comfortable ride over a particularly fast one. Great video! glad I was not the crazy one who couldn't feel a difference in frame material.
Good to hear. I'm glad it's not just me too! Steel frameset options are definitely great value for the price, it's hard to find anything close in other materials.
I’ve found similar. Steel is nice/practical to live with. Whilst they tend to have ‘a feel’ I’ve not found them to be more compliant or more comfortable.
Try finding a steel enduro hardtail frame for cheaper than some aluminum one. I wish you good luck :D It's crazy how expesnive new steel frames are. Barely can find any used ones and then they still want alot of money because steel is real blaa blaaa
@@kaedeschulz5422 You're right, the steel fad has driven up price. Just recently I have had issues finding a cheap older style steel road frame to build a custom road bike for my dad. Steel is real all right, a real pain to find at a decent price now. My steel XC hardtail is based off Kona's 2015 Unit frame. Their frames did run ~300-400 depending on the bike you want and the Unit is steel. Their sizing is pretty good too with many in-between options and fairly cheap used. You can likely pick up a used Unit single speed cheap and get the sliding dropouts from paragon steelworks to attach a rear derailleur. Those dropouts fit most single speeds with those style slides to open up some possibilities. Tons of options but your right, price is not there like it use to be when carbon was king and steel was a steal.
The thing that gets me is you can get a custom steel frame for the price of a really nice carbon or Aluminum frame... For most people custom steel will be lighter, and should always fit better, presuming everything is got right...
Food for thought. I have steel frame Surly fatbikes, and love them for a number of reasons. I agree that tire size and pressure will always be a dominant factor in comfort and performance. Tires are your (or part of) your suspension, even in a car. I’d say this data is most focused at road bikes, where the tires are small and high pressure.
I think at certain point too big tires will make the ride more sluggish. Around 35c might be the optimal spot. Double butted heat treated steel seems to have more springy horizontal compliance without being too noodly which reduces back pain and gives the feeling of so called ride flow. In my experience budget grade aluminium frames were harsh and clunky regardless of tire pressures while also having high speed shimmy on descents.
Exactly.
Also, side deflection is completely left out of the equitation.
@@uvwuvw-ol3fgi think diameter also applies to the equation too since my 26” MTB is quite nimble on it’s 2 inch wide tires where as my Hybrid 700c bike on 32mm tires is quite sluggish in comparison.
I am not scientist but I personally feel steel more comfortable-specifically because I have 2 bikes one a steel and one Alu-frame. It depends on the style on frame.Alu frame can only “flex” one time😂
I'm 57 and rode as a cycling messenger in NYC for 15 years. From my own experience steel really is real.
... and build correctly, such a frame will last longer than I do.
I am currently resurrecting my 1998 Surly Karate Monkey. Owning 12 bikes, and gone through Alum, to Titanium, to Carbon, now making my way back to the Safety of Steel. Only a couple pounds more weight, but a TON more reliability.
I love that you present actual data!! And this analysis also corroborates what I’ve been spouting for years: if you want comfort, ride a fat bike 🤣🤣
It's definitely hard to NOT be comfortable on a fat bike! The tyre spring rate must be well under 5N/mm.
There's no denying a steel bike rides differently. I have 2 road bikes, a steel and carbon. While the carbon does everything better, it lacks character. It feels numb. The steel bike feels "springy" like a spring. Probably because it doesn't dampen the road inputs like carbon. So you like a plastic, stiff yet compliant bike with no character, buy carbon. I'm going to get a modern steel bike and sell my carbon bike.
Steel forks with low trail curves flex pretty well. I think you focused too much on frame and seatpost and neglected fork flex
That's true, but the focus of this video is frame comfort. Might do a vid on forks later.
This is the main reason why many aluminium bikes have carbon forks.
But only if they have rim brakes. Disc brakes ruin any potential flex due to bracing.
@@Cyclingabout should be part of the equation, i think. especially when considering, that bumps through the hands and arms are much more noticeable than through my (considerable) behind. curved steel fork with a forged shoulder is slightly, but noticeably more comfy than my aluminum fork (same wheels).
@@FriedrichSchmidgall It also makes a big difference just how the bend is formed. A '30s or '40s fork with a Russ-type bend at the bottom gives huge compliance to cope with cobble-stones, but a shallow curve half way down the blade will not give much. I would add that radial spoked front wheels also give a very non-compliant ride, and I prefer a tangentially spoked wheel.
High quality steel frames are a much smoother ride. Double butted thin walled steel frames have muluiple reasons for better comfort. High end steel tubing is highly resistant to fatigue, meaning flex can and is built into the tubing. The tubing in steel frames is much smaller diameter due to higher strength and fatigue resistance so flexes with less force. Most mocdern bikes are built on a compact design, short tubes and short wheelbase. This does two things, short tubes are much less flexible than long tubes, the wheels are directly under the rider transfering road shock and vibration. Any such frame is much more harsh to ride.
Comparing a large size Giant defey advanced 2013 with my current steel framed bike. Steel frame is 16 cm longer wheelbase, no foot front wheel overlap, very smooth ride and only 1 kg heavier. Frame design and frame material both matter for ride quality as do wheels, spoke lacing, rim width, and tyre size
What steel frame are you riding? Do modern steel bikes suffer from the same compact geometry issue that aluminum and carbon frames do?
@@Pellagrah Mine is a custom build, while I am only 180 cm tall more 50 years ago a heavy build 110 kg and 46 cm c-c bars. Down tube 28.6 mm Reynols 853 every thing else is 531, centre front 63 cm,
54 cm centre rear. Basically a long wheel base touring bike but built fairly light, could go lighter but 110 kg rider. Wheels are Novatec hubs DT Swiss R500 rims with mini V brakes, 24 DT Swiss revolution spokes front and 24 champion spokes rear rear chainstay are offset to remove the disk in the rear wheel. 32 Conti 5000, Shimano 105 10 speed
@@Pellagrah Most bikes are built on the same plan. To fit in the smallest box possible because transport (container space) is very expensive. Steel is also the easiest to build custom to fit the rider. either lugged is best, fillet braze requires more operator skill as does TIG welding.
16cm longer? Doubtful. You need a better ruler.
Interesting. I switched from a steel HT rigid MTB to an Alu HT rigid Mtb, and I actually got bruises on my love handles. Everything was exactly the same except for the frame and the seat post. The seatpost on the Alu frame was actually not as biffy and straight as on the steel frame.
If your steel bike is heavier, all other factors being equal: it will be more comfortable. More weight = less deflection = less rattling = more comfort. Our friend in the video forgot to mention how weight basically 'outweighs' all the other factors he researched ;).
@@Coerced I took up bike packing and noticed when I added about 12kg to my 26 aluminium hard tail , it was a smoother ride , i could coast the bike easier when going down hill or flat , lots of pros , obviously uphill different story 1🤣 . I wonder if steel bikes can feel smoother cause they are often a bit heavier and coast and ride minor bumpss easier with the weight improving gravity
The "weight" of a material doesn't control its stiffness/deflection 😊
In terms of comfort, I would suggest saddle choice can make a large difference as well. The more your saddle conforms to your shape and distributes the load out to your contact points, the more comfort you will have. I've ridden Selle SMP saddles for years, even though they are ugly as sin, because they fit me better than other saddles and have made a huge difference in comfort.
Saddles definitely make a big difference! Just another spring in the series, but a bit less easy to calculate.
Since sides and nose of the saddle is hard then horizontal compliance/springiness of the bike frame is still important when it comes to giving that feeling of so called ride flow and reduction of back pain similar to therapeutic horse riding.
I agree. And no, saddles are meant to be a hammock, not a simple spring.
That kind of reductionism leads to ignoring evidence in favour of theory. And in theory practice is the same as the theory. But in practice, well...
I bet when it comes to frames the key factor is harmonics and what hertz rate of vibrations different materials usually carry over the best.
Exactly
As a qualified non destructive tester I can confirm than Aluminium is much much stiffer than Steel and will transfer vibrations much more.
As a man who lived off an aluminum bike for over 3,000 days (until the frame fatigue cracked) I completely agree. On a steel frame, the difference is enormous.
I have ridden several mid 90's steel mountain bikes that were very stiff feeling (as much as an Alu bike feels to me). And I've also ridden an early 2000's On-One Inbred (a cult british, taywan made steel hardtail with thin tubes, a long top tube geometry and Dekerf style fork rear stays).
The Inbred has always felt noticeably less harsh on the trail when compared with the thicker tubed, shorter "triangled" bikes of the 90s.
I've always felt that the zingy feel of the On-One comes from the frame twisting "sideways" relative to the vertical plane as opposed to the vertical movement you are focusing on in the video.
My intuition attributes this extra flex to: thinner walled tubes (they bend more easily), smaller diameter tubes (also bend more easily) and a significantly longer top tube (triangles with longer sides, twist more).
As concluded in the video It is not surprising that a structure that has its maximum strength in the vertical direction does not deform a lot in that direction.
BUT, when riding a bike in the real world, the purely vertical loads are far from being the only forces that define how a bike feels, especially when the bike is tilted/leaned on by the rider and goes around corners and the wheels hit obstacles and bumps that impart lateral forces on the wheels.
These more "lateral twisting" forces are probably way more important to ride feel and comfort than the vertical ones. (precisely because most frames are designed precisely to guarantee they are very strong in this direction. For the counter point consider something like the Slingshot mountain bikes of the 90s, the ones where the down-tube was a tensioned cable. Look at the lateral flex on those bikes!)
Don't forget that all key components that are in between the force "origins" and the frame are nowadays typically very stiff. Namely: the rims, hubs and spokes, the fork, the pedals, cranks and bottom bracket.
Also don't forget that most frames nowadays (even steel ones) are built to be very laterally stiff, because this is a sort of assumption by manufacturers that stiffness is a desirable property in general. This is a symptom of the influence of road bike racing (the stiffer the less energy is wasted) and of mountain bike design where in the last few decades everything from handlebar diameter, to fork stanchions, to head tubes to axle diameters became oversized in the quest for more stiffness.
I'd love to see new tests done by applying a twisting force via a lateral load to the front view axis of the steered tube for example (with the rear dropouts affixed to a solid stand).
I do reckon such tests would show that this torsional frame stiffness is more dependent on the actual tube specs and frame design, than the materials per se.
These are just the ramblings of a non-engineer that has been riding bikes for 40 years. So take that as you will :P
I've owned/ridden steel, aluminum and carbon, and I can't tell the difference. I have never experimented with seat stems. In my experience it's tires that make the most difference.
toda la razon
Agreed I switched my hybrid to road tires and it helped but that aluminum frame still buzzes and puts my hands to sleep 😔😔. The problem turned out to be that the frame was slightly to big causing me to ride in a bad position because of the reach . My light weight aluminum road bike still climbs better so weight is definitely an improvement and not a myth 😂😂👍👍.
I think when they're comparing steel, titanium, aluminum and carbon in terms of comfort, they refer mostly to vibrations that are transmitted through the frame material and not visible or measurable flex. The way the frame resonates does give a slightly different 'feel' to the bike, but you have to know how to distinguish it.
Exactly
All metals resonate and can be designed to at a certain frequency. Steel, Al, CF whatever.
There was a study a few years back on fatigue to feet and legs, which included micro-injuries caused by vibrations and shock. The cumulative damage and fatigue can be very substantial in some situations (long off-road touring, for example).
I have bikes made of different materials and designed for different purposes. I've noticed a lot of compliance - but not VERTICAL compliance - in some of the steel frames. It is more like torsional compliance. I can feel a major difference going over sharp bumps and rough surfaces at times.
It's the sort of flex you can experience when you're off the bike, and putting one foot on a pedal at the six o'clock position, and then repeatedly applying a lot of your weight to that pedal, especially when the bike is held at an angle away from you. Other things are flexing also, but the frame flex is very substantial in some bikes when doing this.
I haven't thought much about how this plays out while riding, but I have noticed a "spring" in some steel frames that is other than vertical, and yet very attractive. It makes for a lively, desirable, and more comfortable ride.
Must say I agree. It's only the expensive steel frames of course. As they can be made to flex more and not break (all to do with young's modulus).
Yes, if the labs measured deflection of the frame only from the dropout (why not at the bottom bracket?) and only in a vertical plane, then it is not relevant to the act of bike riding at all because as you say - the bike is always at an angle to the ground. This argument he is making is akin to saying that a bike being aero on the track (no wind) is going to be accurate to the aero-ness in the open road (lots of wind everywhere).
Why wouldn't they measure from the bottom bracket since that's where vibrations are transferred to the cranks, bb, and legs - and its the legs that we want to keep fresh to ride longer!
I like the way my steel bikes ride too. If you can build them to have that perfect amount of torsional compliance, where there is noticeable but very minor amounts of flex - it's a really nice feeling (and it's hard to replicate with aluminium).
I'm just not convinced that torsional flex is a big contributing factor when it comes to comfort, especially on a mountain bike when you have such large tyres anyway.
@@Cyclingabout I'd argue torsional flex is the biggest factor since you proved that vertical frame flex is not. The act of pedaling is asymmetrical with weight on one leg at a time on each side in an alternating fashion, taking the bike frame out of a plane and hence apply torsion to the frame. You feel the frame's torsional resistance to vibrations transferred through the legs.
As I mentioned in your comment above, we need to take into account the rate of springs in a series. Let's say your frame has 2x more flex at an angle, and the seatpost has half as much. The overall spring rate of the system still calculates out to be less than the softest spring, which is still your seatpost or tyres. Sure, the data might not be as accurate as we'd like (in reference to aero testing), but it's not like the spring rate of the system will miraculously change because the bike is on a slight angle.
The problem with the theory of vertical springs in a perfectly vertical plane is that when you ride a bicycle, your bike is not - probably rarely completely vertically aligned to the ground. That being said, the bicycle is absorbing bumps not as they are in a lab (perfectly vertical), but when the bike is ever so slightly tilted. Also, if you are claiming that because the lab could not show measurable differences, that would fly in the face of your preference for the resonance damping characteristics of carbon frames since it isn't measurable.
In fact, the minuscule differences between the resonance damping effects of certain tube designs are added up among millions of vibrations that occur over long timeframes when you are on the bike. Those can be felt by the rider. Those millions of vibrations while the bike is slightly off a vertical plane. Bikes are pedaled, not run by a motor, so you have the motions of balance at play, throwing the bike at an angle while transferring road jarring which I am not so sure the science has tested for.
Interesting idea, there probably is a little more vertical frame deflection at an angle. I wonder how we could test the theory? My personal experience is that the vast majority of the time I'm going in a straight line, so I suspect the lab testing is quite accurate for the most part.
But still, we need to take into account the rate of springs in a series. Let's say your frame has 2x more flex at an angle, and the seatpost has half as much. The overall spring rate of the system still calculates out to be less than the softest spring, which is still your seatpost or tyres.
@@Cyclingabout
I think they should put strain gauges and accelerometers (or whatever instruments they use) on bikes (or on the bottom of shoes and saddles?) ridden outside on all surfaces - keeping the same components for control perhaps. It would be expensive I think.
I believe that your current experiences is riding a bike meant to take a large load and not break, so the torsion of the bike frame is irrelevant, since it has been made to be as strong as possible. Therefore, you are feeling the bike through the saddle , seatpost, wheels and most importantly, tires. Plus, all that weight resists the upward motion of the road surface, forcing the tires to do more of the work of bump absorption.
True what you say about the softest spring being the tires, but this still has significant results in feel.
Many springs of different spring rates are not the same as one spring equal to the softest of that of the series of aforementioned springs. If that were so, progressive springs wouldn't exist - they'd all be linear.
But let's be real here, this kind of force/stress testing needs to be performed in the normal axes so that a benchmark for the measurement values can be easily established for different frames and thus validating the comparison because the test parameters are all the same. It is very hard to simulate all the tilts and bumps in real world because they are random even if you tested it on the same track. But theoretically those can be calculated if the forces in reference axes (normal axes) are known. It is easier to calculate for metal frames because metal is isotropic, but a lot harder for carbon if the carbon layups aren't known.
@CYCLINGABOUT Thanks for the video. I also think this topic about "frame material ride quality" especially the "steel is comfy" is overblown. Carbon can be made to be stiff in one direction and flex in other direction, thus it is very possible to design a carbon frame that takes vertical compliance into account. In my opinion, the components that have direct contact with the rider's body (other than tires) affect the ride comfort/quality more; so seatpost, saddle and handlebar. People have been talking about "I converted from carbon to steel and it's more comfortable" but they basically singled all aspects about the bike into one "steel vs carbon", thus ignoring other factors. Funnily enough, those who think there are significant differences between frame materials don't have data and almost always only provide anecdotal evidences.
@@sirchristophermcfarlane9377 If there was no study on the topic, then people's conclusions are not true? Does this mean that only where there is a study can there be fact?
@@SurpriseMeJT by "people" which one did you mean? The ones who say that frame materials make a big difference or the ones who tested these frames and concluded that there was no big difference? If you're talking about the latter, then technically their conclusion is true until proven otherwise. And yes, since fact must be proven with certainty and/or observed, they do require study to be established as a fact.
pure worthy content without any bloat! What a simple cure for today's overabundance of drivel and hot air just to be heard. Keep it up because the point is sharp.
I have owned both steel and aluminum road race bikes for years. My personal experience has always been on the same tire size, same routes, same rides. And steel never beats up my body as much as aluminum does. The fatigue from riding on aluminum has always been more noticeable, fatigue from riding steel is non existent.
Same experience
because comfort ist not only vertical compliance between rear wheel and saddle
Same experience
Expensive heat-treated steel is stronger and can be made thinner to flex more without breaking. Cheap steel bikes cannot do this and feel terrible. It's all to do with young's modulus. Aluminium frames cannot tolerate as much flex. I can littery feel a steel frame flex when I put on the power, so it is very noticeable to us humans. Never got the same flex as put on power from carbon or Ali, so something is making a difference, even if your measurements do not pick it up? I have ridden high-quality low weight Ali frames and they are not the same. They deliver the power more efficiently but also lack feel and spring (both in power delivery and comfort compared to an expensive steel frame). I would suggest it's the way a steel frame flexes, or how much it is able to flex. Perhaps the tests need to look more into real-world conditions - not just flex for a given once only load. Of course, tyres and post make a difference too.
The data suggests that any noticeable vertical deflection difference between frame materials is just a placebo. But honestly, if you think it gives you the edge, that's great! The placebo effect is a very good tool if you can use it to your advantage. 💪🏼
@@Cyclingabout hahaha, maybe! It also makes me feel better knowing it is less likely to snap and can be easily repaired :P
The video discusses vertical compliance which adds to comfort. The 'mushy' feeling you get when putting power through a flexible frame would be the side to side compliance. If you put down a lot of power at a stop on on a cheap bike frame, you can see the bottom bracket flexing from side to side.
Due to the triangle shape discussed in the video, despite this side to side flex, there is very little vertical compliance
@@aarontasker6423 I recall a professional reviewer talk about it like a spring, it saves energy for when you get back on it. Some bikes are designed with it built-in. It's a nice feature, and when the amount of it suits your ride it's amazing the flow and zest it adds. Frames I have had that have this power spring have been some of the best tracking frames I have owned :)
@@andrewnorris5415 If it all comes down to Young's Modulus, then why can you feel steel flex (190-215 GPa modulus) but you can't feel aluminum flex (69 GPa modulus)? At the end of the day, aluminum's modulus AND yield points are much lower, making it more flexible than steel. While things like tube geometry do come into play, you cannot cheat the metallurgy.
My most favorite mountain bikes I've owned were cro-mo and they both rode smooth and beautiful but after watching this video now i believe it was more to do with the geometry than anything else. Both of the Steel bikes fit me perfectly but all the alloy frames I've had a shorter top tube for a similar seat tube. I have a carbon seat post in my steel bike now and when i checked bugger its got a fair bit of flex. So now I think a carbon post and good geometry are more important that light weight materials.
CroMoly is an amazing material. It is so strong in the ways you want a bike frame to be, you can get away with ridiculous thinness if built intelligently.
Thanks for this.
Always wondered at what point frame material made no difference. 40mm tyres seems that point for yourself, interesting to know.
(I'm riding aluminium frame, 35mm tyres, redshift suspension stem, redshift suspension seat post (recent addition))
You'll definitely have a very smooth ride with the low force required to deflect your stem and post!
I too have the Redshift combo on an Alu DBack Haanjo, but with the Rene Hearse (compass cycles) 48mm Switchback Hill 650b's . The rear is on a 25mm int width rim, the front is on a 40mm wide that expands the tire to 56mm. Topped off with a Brooks b17 (w/cutout) and Tasis Fat Tape on top of some fizik bar gel. Not for everyone I know, and not wining any Tuesday Night World Champs., but it rides like a Lincoln Town Car, and keeps this 240 lb, 51 year old out there on the bike.
Very informative regarding frame comfort! I'd be interested to see a comparison in fork materials as that relates to comfort (aluminum vs. carbon vs. titanium vs. hi-tensile steel vs. chromo steel). My guess is that a chromo steel or carbon fork will be more comfortable than an aluminum fork, assuming constant handlebars and thin tires.
Aluminium forks are even more more overbuilt than aluminium frames. And cheap bonded Aluminium steerer/carbon blade are SO very heavy and overbuilt. This is because fork failures = death and lawsuits so you don't take chances there. In comparison a broken BB shell is no big deal.
It's still going to be a carbon fiber fork no matter how overbuilt that will be the most comfortable. As far as weight goes as long as it has at least an aluminum alloy steering tube It's also going to be lighter. A carbon fiber fork is going to be stiffer and have the best steering response.
As much as I like my Lemond Zurich 853 steel frame. I can't ever see putting a steel fork in it. The very first thing that I would notice is the handling will change. Not for the better either. There isn't enough rake in a steel fork in a road bike to gain any comfort factor because the internal dampening of carbon fiber is well beyond steel. That can be said about the handle bars, stem and seat post. Carbon fiber as a material is so engineeriable that it would be difficult to shape metallic materials to compete.
The only exception I can think of is old school rims . The flat light weight box section tubular rim has alot of vertical compliance. Relatively many thin double butted stainless steel spokes go a long way to provide thst. The front wheel having rim brakes and dishless can be incredibly strong and laterally stiff. Just don't hit an immovable object with it., as it will catastrophically fail. A heaver rim with more spokes in back will round out the ride. Alloy nipples will shave noticeable mass where it counts at no penalties. Except for salt loaded winter streets and the spokes were cut long enough. Obviously I don't care about aerodynamics any more. But I really like 28 mm tubulars . Ironically easier to obtain these days with better flat resistance. Put a nice riding sticky one on front and one that resists flat and wears longer. 😊
Awesome to see someone approach this sort of question with some real research and data instead of marketing buzzwords and biased impressions. Subbed.
Cheers!
To me, vertical deflection is a small and only one component of comfort and road feel. When you pedal hard, the energy goes into twisting the frame and your body is working against it. If the road vibrations are transmitted to your body in the process (at contact points) your will fatigue faster and not enjoy the activity as much. If you are climbing out of the saddle and the frame flexes back a little it is more comfortable and fun even though it may not be as efficient. Same goes for tires:many other considerations such as how well it grips under high speed cornering or how supple the sidewall is under angular forces, determine how comfortable and fun it is to ride.
You make a very important observation here. Not only the pedaling but also the bumps from the road/trail surface and the forces the rider applies on the handlebars all contribute to lateral twisting / flex that is usually deemed undesirable today (hence a lot of frame and component development over recent decades has been targeted at eliminating/reducing this type of flex)
We end up with very stiff components and frames by design, that are then compensated for with larger vol tires and suspensions (front, back, seat tube, saddle). Thus it is not surprising that these components become way more important than the frame for comfort. That is how bikes have been designed towards.
After an hour on an aluminum frame, I'm ready to be done. That doesn't happen with steel, carbon, or Ti. Dropping tires to 30 psi didn't change this. This is my experience, not a theory.
From my experience it is mostly about the fork, it the front is a steel fork it is very likely to have a bit more flexibility than a aluminium one or a carbon one, especially if it has more rake. That puts less harsh impacts on the shoulders and makes rides more comfy. The variations of stiffness of the rear is not significantly different. Everyone who changed from a undamped mountainbike to a front shock absorbed bike in the 1990's can understand that.
I agree, I think he left a lot out by basically skipping fork geometries.
Most weight is placed on the rear of a bicycle.
@@risesir Yes and I heard the weels are round!
I can see the triangle has no flex but the front fork is different. That may see a bigger difference between materials and shape?
You're looking at a short lever inserted into a long truss (seat-post into seat tube), the point you're missing here is on the other side of the frame. The long lever inserted into the short truss member (the fork into the head tube). The majority of deflection and bump attenuation is going to occur at the front of the bike. The fork reacts to a bump (regardless of the fork material) and transfers this up to the head tube. There's much more force at this location because of the long lever (the fork), the way the head-tube takes this deflection and transfers it through the frame is going to play a big part in ride feel and quality. Its a simple matter of material science that aluminum has a more tightly packed structure (google images of aluminum structure and steel). Steel has a much looser packed structure and will in fact allow vibrations to smooth out through the material. These micro vibrations make all the difference.
Good explanation., seems like the fork is most important if you look at it that way!!
Exactly how i felt after watching this in 2024. I will never buy an aluminum fork again. Carbon and steel forks only for me. Bikes with 2 inch or wider tires are comfy enough for me to tolerate an aluminim fork with minimal complaints on comfort.
I’ve gone from steel to aluminium to carbon to aluminium and recently back to steel I will never go back to anything else again
Glad you like your steel bike!
Same here, steel frame steel forks. The only test I need is how my body feels after a ride.
People don't really know about modern stainless since it's rather rare to see stainless frames, but modern quad-butted stainless frames are barely any heavier than titanium and same ride quality as typical steel. No corrosion issues or chipped paint, and you can polish the frame up easily with steel wool. I'll never ride anything other than steel or titanium again, went through 3 aluminum frames and they were all horrible. Snagged a stainless Vaya Travel frameset in 2015 and it'll likely be the last frame I own, I love it, and already put thousands of miles on it all over the US and AUS
But are you comparing pure samples or mixed? Usually aluminum bikes use carbon forks as do many steel frames use carbon forks and many metallic frames will have carbon rear chain stays and/or seat stays.
@@boxlid214 Any idea who makes stainless road disc frames?
Totally agree, I always laughed a 'Frame Ride' reviews, when what the 'Princes & the Pea" reviewers were actually telling you about were the stock speced tires.
It's cool to see some websites using control tyres for their tests (eg. CyclingTips). I'd love to see them go a step further and use control seatposts, but even that gets a bit tricky with varying seatpost lengths, different seatpost shapes (aero, proprietory) and diameters. Then again, where do you draw the line in terms of describing comfort? Control handlebars, bar tape, saddles?
I don't understand the bike reviews of the parts since you can change all of them very easily. Some parts you should change to make the bike fit better (saddle, stem, handlebar, grips). It's the frame that matters. But if you think that reviewing "Ride" is useless then where do we need any reviews? Let's just watch bike commercials.
@@Cyclingabout it's funny you say that, because while your mechanical analysis is spot-on, my thought during the video was "vertical compliance is a funny way to define 'ride comfort'".
My experiences certainly match your data, that tires dominate vertical compliance, but when I think about what bike produces the "most comfortable" ride, I'm not just thinking of how jarring the ride is, but also how much the frame flexes laterally under load, how sensitive the steering is, and how hard I have to work to make it go (I would describe high rolling resistance as uncomfortable).
@@natbarmore "Comfort" can certainly be interpreted in many ways, and with all of the variables, almost everyone will have a slightly different take. Thanks for sharing yours!
I think there is a lot of merit to measuring force vertically. Have you ever ridden a full suspension bike? It's pretty hard to ride one (with a high or low lateral frame stiffness) on a trail and not feel comfortable.
I've also found that I can make my laterally compliant steel bikes "uncomfortable" to ride by using firmer saddles, stiffer seatposts, and higher tyre pressures. And my stiff aluminium race bikes "comfortable" with more padded saddles, flex carbon seatposts and lower tyre pressures.
As a result, I tend to think lateral frame stiffness falls into the 'ride feel' category, rather than the 'ride comfort' category.
But then again, I think there's a case to be made that when mountain biking on rocky sections of trail, that a frame with less lateral stiffness will be more comfortable due to the additional off-axis directions of force!
@@Cyclingabout all good points. I've test-ridden full-suspension bikes-particularly liked a Softride with suspension beam (instead of seatpost) and suspension stem. Rolled up a curb and didn't even notice. But I don't ride off-road, really-gravel roads and paths sometimes, but nothing that merits a mountain bike or similar. So I'm talking strictly comparing the comfort on various sorts of surfaces that might be loosely called "roads" or "paths", where the handling obstacles are potholes, curbs, broken glass, and cars, rather than roots and rocks and tight switchbacks.
I guess this could be the reason I settled on Brooks Cambium saddles for my bikes, more vertical compliance in those than tyres or seatposts.
Is the cambium ones better than the Brooks leather saddles with springs?
I had low spec steel framed Specialized MTB with no suspension fork back in the early 90's which gave a lovely, quite flexy, smooth ride compared to something similar in aluminium. I don't think it was my imagination..........
Did some jumps with a steel MTB. Full steel. Not as terrible on landing as I thought. I think its all simply the fork. I mean. Look at the shape, it's usually slightly bend at the bottom, modern forks ain't made that way
This is horse dung. Diameter of tubes, length of tubes, wall thickness of tubes, shape of tubes, butting of tubes, elastic properties of the material, and construction design of the frame all contribute to the ride quality of the frame. High strength butted steel tubes are highly fatigue resistant are much smaller diameter as so flex more, butting of tubes stops vibrations.
hum, it's like a religion
@@Mrkeke35 More metallurgy engineering and science. Religion is based on belief rather than observable, testable and predictable realities.
@dan2304
So you’ve done the testing on vertical compliance for frames? Not just the materials but the finished products?
@@jamesward3567 Quite, but not so much because I have found what I want to ride, at 75 don;t have much riding left. If I am lucky I may wear out the new tyres on my two bikes but I am not betting on it. Many years working as an mechanical engineer that stuff was my work.
I have many steel bikes and they are smooth riding. Get on an aluminum frame and it feels like it is jarring me to death after steel or carbon. I still have aluminum frames but they have shocks or carbon forks. Otherwise 😮
Very cool! I think something to take into account that isn’t talked about in the video is that often times aluminum or carbon frames have oversized (diameter) seat post where is steel frames often have 27.2 or smaller diameter posts. Obviously the narrower seat post will deflect more and while this doesn’t necessarily make steel more compliant then aluminum, our perception of it while riding is that it is more compliant.
You're right, big oversized seatposts are rarely found on steel rigs.
Good info. I find that I change body position significantly if on rougher terrain. It is easier for me to absorb rough terrain on my gravel bike than my "cruiser", but also tires me out (pun intended) faster on my gravel bike.
I find that a long seatpost, a quality steel frame, carbon bars, high volume tires tubeless, and carbon fork helps
Thank you so much for using the correct terminology!!!!! It's a pleasure watching your videos and analysis. Very thorough and concise. A+
That was genuinely very interesting. Thank you.
As an experiment, if you can zip tie one or two 5 lb. hand weights to a bottle cage, the ride comfort improves favorably. BTW, this video is the most accurate ride analysis ever made on YT.
I'm always surprised by all these fancy looking plots the industry shows. Wouldn't you need a bode diagram that shows the amplification of movement of a frame at different frequencies? Also, carbon might sound dull as it dampens in opposing directions. However, the young's modulus of carbon fibre is a lot bigger that steel's and therefore it won't flex at all, stressed in its direction.
Quite difficult to reduce this to a "dull sound"
Very strong position using sound principles in mechanics. Would be interesting to hear how the opposing view would refute this strong data. Thanks for the video!
I would love for someone to make a video stating the opposing view!
@MJD Exactly,all frames are built differently,to say they are all the same and ride the same........its a strong viewpoint for sure. Seat stays can flex,chain stays can flex,forks can flex quite a bit and it can be seen while your riding. Fork is part of frame.
Very Cool. So based on their numbers, steel dampens vibrations ten times better than Aluminum. I think OP is forgetting that the ringing when he thumps the steelframe IS the dampening happening, as the whole frame transfers that energy into the air as vibrations, while the stiffer carbon or aluminum frame is transferring all of that energy straight into you!
The vibration attenuation on a bicycle is much more than a frame. Your body will absorb some, but so will your luggage/tyres/seat/carbon seatpost etc. The more components with high damping properties, the smoother your bike will feel. I've personally noticed that with 40mm tyres I cannot notice a difference in frame materials. And when I put my bikepacking bags onto my road bike, I think I'd struggle to notice the difference between frame material there too. Anyway, hoping to make a video on this topic with all the data available. 😎
@@Cyclingabout I would tend to agree. With any fatty tires or springy seatposts like that, any differences in frame material would be overwhelmed by the large squishy tires or suspension seatposts, but I definitely DID notice the difference on my roadbike with 28mm Gatorskins when I replaced the frame. If you insist on constraining your analysis, you are technically correct.
Great video. Keep it up. Educational videos like this make the world smarter. That in turn makes the world a better place. Cheers!
I'm new to cycling and thinking about building a bike...found your vid really informative
Hey there, really interesting video. I have some thoughts…
when I ride over rough stuff I usually stand up which in turn means we have to consider a couple of factors not considers it your video that ant that might or might not put a bigger emphasis on the differences on materials.
when I stand Seat post and saddle have no influence putting more emphasis on frames and add Cranks to the picture.
Definitely handle bars are a massive factor in the feel of a bike as well as grips. Usually peoples hands are more sensitive than their butts.
more and more carbon frames are not built in classic double diamond design but other shapes that are not possible in metal that allow extra compliance.
Geo, the shorter a bike, the more upright you sit the more the discs in your spine get tortured...
so much more factors that could be considered...
also when on the seat and pedaling, pressing down a pedal means taking weight of the seat. hence totally changing your stack of springs. the more power I put in the less weight on the seat.
in this case only tire and frame compliance can give you added traction climbing up a steep gravel road.
Well, the reality is really there is nothing else in this world that people ride around on that people would consider better without suspension or that even still exists without suspension but still some cyclists insist.... only reason we have super uncomfortable road bikes today is UCI rules and bike companies complying to them. How many people really rides in UCI races?
Not only does this give us really uncomfortable road bikes, UCI also makes sizing really inappropriate for taller riders as there is max measurement...
well, Ok sure Forklifts also dont have suspension, so all of the fork lift drivers out there, your are good to continue on your hardtails
@Fight Film What about horizontal compliance/springiness? Double butted heat treated steel seems to have more springy horizontal compliance without being too noodly which reduces back pain and gives the feeling of so called ride flow similarto therapeutic horse riding. In my experience budget grade aluminium frames were harsh and clunky regardless of tire pressures while also having high speed shimmy on descents.
But is vertical compliance really all to take in account? Could it be that loads from the side on uneven surfaces affect comfort as well? A steel frame with thin seat stays will react different to forces by roots, tracklines or stones than a stiff oversized aluminum or carbon rear end?
Good video. Good to watch. But you are over simplifying this. This n/mm is just one aspect of the equation. And you only examined one direction, but frames are working in 3D. The other thing is resonance, you can feel the difference. Just because you do not feel it, does not mean that other people can not. I have a numbnes problem in various body parts unfortunately, and there is a big difference between frame materials, numbnes comes much earlier on an aluminum frame. Btw I am engineer.
Totally. I like fast downhills,some are rough. My carbon roubaix can and will catch air off bumps,bumps steer it.. My steel frame roadbike sticks to the road and turns on a dime.
But the one direction that was tested in the lab totally makes sense because in reality it is the direction where most of the force comes from during a ride and also the first contact points. Sure, he is oversimplifying it but it is a less than 10 minutes video. I would appreciate more if he also includes the basic theories of the physics, the test methodology, environment, setup etc, but it would take too long and people would be bored to death.
Now the thing is that, this vertical force is measured and can be used as reference, so say you want to calculate the force acting at a certain angle, you can derive it from the reference. Metal is isotropic so theoretically if you have the frame dimensions etc you could calculate the forces acting from another directions. However, as said in the video, the vertical flex of frames is very small, so assuming that the frame will flex more (thus "contributing" to ride comfort) in another direction makes no sense except if it was designed that way.
Your numbness problem could be caused by so many reasons; different frame geometry, riding position, your body condition, thickness of bar tape, the saddle, seatpost, tire pressure, road condition, speed at that time, etc.
Also didn’t say much about feel through the pedals. Seat feel is of course important, but road buzz through the pedals also affects road feel. Also, all things equal, a heavier bike will always feel smoother than a light one. Maybe steel feels more comfortable partly because it’s mass is greater and it takes more force for a hit to move the frame against the rider contact points.
Carbon is different for every bike, it can dampen vibration really good, or it can rattle your bones to death, it just depends on how the fiber is wrapped. Steel can be just as light as aluminum, especially stainless. Modern steel has come a long way. They simply use modern alloys that require far thinner tubes, then quad butt the ends to get enough material at the weld points. A properly built stainless frame should weight roughly the same as titanium. Look at SpaceX and Tesla deciding to use a new stainless alloy to build the Starship and Cybertruck. A few years back nobody would've ever thought steel would be a good idea in a rocket lol
Presentation is nice and simple, but the good engineers out there are all thinking the same thing "Dunning Kruger effect at work here" ...... Let the misinformation continue.
Tire width and pressure always supersedes frame material, but one should not discount the latter. I had a 2010 Jamis Supernova and a Lemond Tourmalet 853 steel. The former ran 32mm knobbies and the latter ran 25mm slicks. Both were very comfortable. I once made the mistake of using the 25mm wheelset on the Jamis. It was so uncomfortable I couldn't sit down for more than 5 seconds!
I bought a very expensive Ti frame and it’s amazing how smooth it is. I think you forgot to consider how much it helps if you riding on a cloud of hundreds. 😉
More money spent = more comfort. That's a fact! 😎
I've got a thirteen year old 2nd hand MTB frame off ebay that cost £40. The comfort of biking on a budget!
@@Cyclingabout when you say more, what do you mean? More than 5k? What about those aluminium premium frame? Thanks
@@PhiyackYuh It's a joke.
vibration dampeners usually work with tuned mass between flexible parts. steel frame may not flex any more, but it is just the weight of it that acts as a damper between the tires and seatpost flex. So it's not just placebo, it's the weight of it. also the example of harsh bike has very tall triangles. so it has no flex. with BMX style frame at very low triangle it flexes more.
Вольшая неподрессоренная масса комфорта не добавляет. Демпфирование это преобразование энергии, а большая масса рамы никуда не рассеивается.
Thanks for the effort making this video.I have both steel and aluminium frames hardtail and I cannot tell the different, but have always thought I am not good enough to feel the different. The video pretty much explains well for vertical compliance. I bet there will be huge arguments over whether this is true or not in the comment section. Though, it's good that we keep thinking, making more connection in your brains.
I would love to see some data that changes my mind!
This came up on my feed, and based on recent experience, I concur. I'll explain.
For many years (38 to be exact), I've had a Marukin M420 road bike. I recently had it overhauled by my LBS, which put on 27x1 1/4" Panaracer Pacela ProTite tires on it. ProTite is Panaracer's puncture protection system; it's implemented by an extra band of material between the tire tread and the carcass. Because of the ProTite protection, the tire has a rougher ride. I feel almost all road imperfections, including the individual stones in the pavement.
OTOH, same LBS had a vintage Cannondale ST500, which I purchased and had overhauled. However, because it has an Al frame, the LBS put on regular Panaracer Pacelas; they're the same 27x1 1/4" size as well. The regular Pacela doesn't have the ProTite puncture protection, so it offers a much more supple ride. The Cannondale, in spite of having an aluminum frame, rides MUCH BETTER than my Marukin does! The main difference is one of the spring force variables cited in this video, mainly the tires.
Years Ago, I rode a bike with an aluminum frame, and it was stiff and jarring. The bike had a suspended seatpost. However, I don't know what tires the aluminum bike had. I can't explain why the aluminum bike I tried out had a harsh ride. OTOH, based on my recent experience with my two road bikes, both of similar vintage (mid-late 1980s) and their different frame materials, my Cannondale rides much better; the only major difference between the two (besides frame materials) is the tires that each uses. The aluminum Cannondale, with better riding tires, rides better. Thanks to this video, I now know why. THANK YOU!
Nice. Seems like shock absorption is all about tires and suspension. However the frame contributes to dampness. I can definitely feel the differences in materials. Steel has a characteristic feel compared to Aluminum. A carbon Bianchi with countervail is super smooth!
YOU GET A FUKKEN SUBSCRIPTION FOR THIS DUDE. SO GOOD. Love the use of data. Honestly, I came for the clickbait title, but stayed for the data.
I
I feel like you're reading my mind because I've come to the exact same conclusions over the last couple of years, and have been meaning to write an article for a while. I always try to explain this to people, but they don't understand because they've tried x aluminum bike and thought it was stiff and y steel bike and thought it was comfortable, yet they haven't controlled for tires, tire pressure, seatpost length, saddle, fork, handlebar, etc etc. Or too stuck in the "steel is real" thing, thinking that steel has some magical quality that allows vertical compliance, when in reality it is the stiffest material used for frames (and also damps vibrations the least, iirc?). Not that steel doesn't have other benefits.
You might look into framebuilder Rob English (English Cycles). He has a masters in mechanical engineering. Despite using the thinnest seatstays in the business, he also says that frame vertical compliance is a myth and thus designs to maximize seatpost length.
The single exception to all this are vintage rim-brake steel forks with thin walls (this does NOT include most unicrown forks e.g. Surly-type bikes, and it doesn't even include many lugged crown forks). Aluminum can't be made to flex enough in a fork due to fatigue.
I'm glad we're on the same wavelength! Rob English's work has come up in my research for my next video, and I read a very similar statement he made about his 'pencil' stays.
Your logic is flawed, steel frames have narrower tubes, they flex more than Alu with wide tubes.
@@digbysirchickentf2315 It's not just tube diameter but also tube wall thickness, and I think wall thickness varies a lot for steel frames and forks. Not sure about aluminum. If you get a stock steel bike, especially one designed for touring, it's gonna have fairly thick walls (although touring bikes have long chainstays, which means long wheelbase, which probably adds a lot of comfort). If you get a custom steel bike where the builder knows your weight and uses tubes no stronger than necessary, it's going to flex more than stock steel. But like this video correctly points out, tires matter way more than anything else.
@@flt528 top end steel frames(the same can be also said for aluminum as well) use tubing from a stronger alloy and/or heat treating. This allows a lighter walled tubing to be used which will be flexier assuming comparable wall thickness. That said frame rigidity is largely overrated. Most of the hype of the stiffer is good way of thinking is due to marketing. A few decades ago it was all the rage with thin walled Reynolds 753 and Tange prestige tubed frames with how it was so compliant and comfortable.
@@flt528 of course high quality bike frames are made of thin walled tubes.
Try study triple butted tubing...
The reason for large diameter Alu tubes are (...were) compensating light thin walled tubes with strength through larger diameter.
Danish Principia were head of the game in that development...
Excellent analysis on vertical compliance. Though I'm curious why you didn't consider fork, stem, and handlebars? IME, the bumps coming up through my hands have a much bigger impact on my discomfort than anything coming through the back end.
(I have a sprung Brooks saddle and a Softride suspension stem on my primary bike, and when I ride a different bike, it's the stem I miss the most.)
I understand the video is about frames but I think the idea of steel=comfort always came from curved steel forks that were designed to flex. Also there are some steel bikes (don't know off the top of my head) which have specially shaped rear triangles in an attempt to allow the tubes to bend, which would allow an action similar to mountain bike rear shocks. Not common, but worth looking into as they are a definite exception. overall a nice video.
In theory the steel blades flex a bit more. On practice especially a road bike. There isn't really enough rake in the fork to take advantage of it. It needs to happen as near to the hub as possible. Any flexibility in the blades near the crown is felt in handling. And that part also needs to be the strongest. I'm not saying it is not possible to make a nice steel fork. But it's expensive. High quality steel is essential. Complex forming of the tubes is essential. And then it takes experience to bend them and put it together. At the end you have an expensive fork that weights more than Carbon Fiber. There may be the same vertical compliance, but the lateral compliance ( lack of stiffness) in steel will be greater and undesirable. And the Carbon Fiber fork will definitely have better internal dampening. I believe the old school rims had a much bigger factor in ride comfort.
If you're having problems with vibrations then fit a suspension seat post and use cinelli gel bar tape.
A quick question on vibration attenuation
You stated in the video that on bikes with narrow tyres and no luggage, you prefer carbon fibre bikes as 'carbon kills the road buzz'
You also stated that vertical compliance between steel vs carbon frames factors very little when taking into account springs in a series. Hence carbon is more comfortable without any noticeable differences in frame vertical compliance
Are there any vibration attenuation differences between nice steel vs cheap aluminium which may result in the comfort which some purport? (on bikes with thin tyres and no luggage)
Otherwise I really enjoyed the video, thank you for taking the time to make this
There are undoubtedly differences between a cheap aluminium frame and a nice steel one when you run narrow tyres and no luggage. I couldn't find any strong data on the matter, but my personal experience is that 40mm+ tyres are damping very large proportions of vibrations from the road, so that is probably where I wouldn't notice a difference between a cheap aluminium frame and a fancy steel one.
@@Cyclingabout I 100% agree with you on the frame having minimal difference with large tyres etc. I believe that the belief of steel being more comfortable would have originated in the 70s and 80s where mountain biking was not too popular and road bikes would often run 18mm tyres. Vibration attenuation would therefore be very important when it comes to absorbing the road buzz
Whilst not on bicycle frames, this paper found that the vibration attenuation (damping ratio) of steel is almost double that of aluminium www.sciencedirect.com/science/article/pii/S1877705816302284
I can imagine therefore on road bikes running skinny tyres, you could definitely state that steel was more comfortable than aluminium due to these properties
I agree that steel bikes ride smoother when comparing bikes with narrow tyres. And yep, I'd say the rock-hard 18mm tyres and 'square' steel frame weren't doing much for ride comfort back in the day. 😂
@@Cyclingabout What is a 'square' steel frame? parallel fork and seat tube?
I still feel like the narrower tubing in steel and titanium does less to transfer "road buzz" to my body than aluminum and carbon. And the sharp, brief "tink" you get when tapping alu/carb., as opposed to the ring of steel is actually an indicator that the steel moves more, vibrates, than does the former, not less. That longer ring is an attenuation of the force applied to it, smoothing out the buzz. For bigger bumps this may not have the same effect, which is what all your data was measuring.
That said I'll definitely be investing in a good seat post. Do you have a favorite? I'm about to purchase a Surly Ogre and will be kitting it out soon.
Great videos, I've watched a bunch of them recently. Well done.
Thanks for the vid and the all work you clearly put into it. Bike designer Mike Burroughs (r&d for Giant for many years) mentions in his excellent book 'Bicycle Design' that there is no inherent difference in terms of rigidity between the two materials, but because steel is stronger you are able to use narrower tubing allowing a less torsionally rigid frame. Aluminium is weaker so thicker tubing is required leading to a stiffer frame. You also don't need much of an increase in tube thickness to acheive an exponential increase in strength. One would have to build two identical frames with identical geometry, tube diameters, wall thicknesses and subsequent spec to be able to perform a valid comparison. As many have mentioned there are many factors contributing to the flex of a bicycle so presumably you'd need to eliminate all variables save for the frame material. So really you may be right in your title but you'd need to risk building and riding a thin tubed aluminium frame..! Of course, we have carbon now so no need to try :-) Just some thoughts! Cheers
Most mass produced aluminium frames use very thick tube walls, like 1/8" thick AL vs 0.04" CrMo. I think there is some improvement with hydroformed tubes that kind of do what "butted" steel tubes do, but Aluminium fatigue is still huge unknown risk so I don't think you could ever really get that thin. Carbon plastic is indeed the best bet.
I think I mostly agree, but this is looking at vertical compliance at the seatpost - what about at the handlebars? The vertical spring system there is tire-rim-nipple-spoke-axle-hub-fork-stem-handlebar, obviously the tires are still very important, but many steel forks do appear to have pretty substantial compliance even relative to tires and certainly relative to aluminum or carbon forks. Is it possible that the swept steel fork design and its relative compliance explains some of the perceived comfort difference there?
I also think it's worth mentioning that steel frames have in somewhat recent years been associated with trends of higher tire clearance and several other comfort-related geometry innovations, since steel is more easily worked on by individual framemakers and also seems to be preferred by the alt-biking/xbiking crowd. So it could also be a correlation between brands like surly or salsa producing highly comfortable steel bikes that allow for things like wider (lower pressure and softer) tires, luggage, etc. and allow for or encourage comfort modifications in the way of saddle or alt handlebar designs too.
7:40 look at the wheel set up on that tractor in the background. Now that's something you don't see everyday.
You don't live in the US Midwest do you? lol
Anybody who says 'there is virtually no difference in the virtual compliance of bicycle frames' has apparently never ridden a Trek hybrid bicycle from the early 2000's. I don't give a damn what kind of tires you put on it, it rode like crap.
The placebo effect that you mentioned is mainly due to the flex at the bottom bracket area. Since steel bike will have a cushy feel while pedalling compared to carbon bike, the perceived comfort feeling might be higher.
5:30 To achieve most of vertical compliance all bicycle parts should be matching set. Including socks!
I've experienced the most increase in comfort with a carbon fork and especially handle bars. Even on thinner tires the dampening is noticeable better, actually most noticeable in regular city riding over badly maintained bike lines or cobblestone streets.
Yep, pairing good handlebars, soft grips and carbon fork together creates a super smooth front end!
Frames also deflect side to side - with every pedal stroke. You can see it if you look. Chainstays also flex to the side when turning - harder to see but you can feel it. Forks delfect in both plains - you can see it when you stand on the pedals.
Thank you for this video. Excellent analysis.
I see some BTL comments are trotting out the mythical difference in feel between common seamed high tensile steel tubing, and thin-wall steel alloys such as chromoly and mangaloy (Reynolds 531, etc). This misses the point you clearly make. Much work has been done by some of cycling's most respected engineers and scientists (as opposed to marketing departments and other sellers of magic pixie dust) to debunk this hokum.
Here's the late Prof. D.G. Wilson on the subject:
"The goal of increased strength or stiffness is somewhat in conflict
with elastic compliance for comfort over bumps. Actually the main arena
for this competition is the handlebars, and to a lesser extent the seat,
cranks, and fork; the rest of the frame plays no role in softening bumps.
There is probably value in trying to increase the handlebars’ torsional stiffness while maintaining or decreasing vertical stiffness." (David Gordon Wilson, Bicycling Science, 3rd ed. MIT, 2004, p. 367).
Further :
"In Papadopoulos’s limited experience of blind testing (varied tire
pressure +/- 1 bar, varied bicycle mass +/- 2 kg) or double-blind testing (varied
frame stiffness and material) of bicycle characteristics, riders could not
demonstrate anywhere near the powers of discrimination among alternatives that they claim to possess. We speculate that many ‘performance’ sensations are imagined; demonstrating otherwise is a promising field for determining what really matters." (p. 302).
Finally:
"David Malicky (1987) performed a double-blind test of stiffness perception, using bicycles with frame tubing of relatively high and relatively
low wall thickness (with mass added so the bicycles would weigh the same). The test population of racers could not perceive any difference in stiffness among the bicycles. (p. 367-8).
Sorry for the long comment, but as a cycle industry veteran, this is a subject close to my heart.
I hadn't seen some of those names before. Interesting stuff! If you're into podcasts, check out the Marginal Gains podcast on cycling placebos... I think you'll like it: marginalgainspodcast.cc/the-placebo-effect-and-marginal-gains/
Gratitude for sharing that Michael. An eye opener.
Frame choice is important, but not for some placebo claims or imagined/non-verifiable benefits.
@@Cyclingabout thank you! An enjoyable listen, and interesting on a number of levels.
would a full suspension Mountain Bike be far more comfortable for long touring rides, given how
front and back are suspension and how they have wider tyres ?
Suspension and wide tyres would indeed smooth bumps.
Though full suspension would require carefull adjusting: If rear suspension is any too soft it will move from force of pedalling wasting power.
Also full suspension adds more parts to wear/need maintenance.
Wider tyres wouldn't make difference to that and suspension seat post would be simpler to maintain compared to suspension in frame.
7:50 "But on my bikes with narrower tires, I've always preferred the way carbon kills the road buzz." So this "myth busting" video doesn't apply to bikes in the race/endurance below 40cc tire categories, where frame materials/design matter. You missed differences in fork compliance, fork rake, head tube angle, fork materials/layout. Major oversight! Many aluminum bikes use carbon forks.
Most uncomfortable bike I've ever ridden is aluminum. I still have it, and it still rattles out my fillings when I ride it. This is largely due to the steel fork, but also due to dropped seat stays and bad geometry circa 2000. All aluminum bikes are not created equal.
Yeah, the race/endurance bikes are where you'll notice a difference in terms of vibration attenuation.
I didn't cover the front end of a bike, because the head tube has virtually zero vertical deflection. I might cover the topic of fork comfort at a later stage.
Front end matters a lot more than rear seat stay compliance. Fork is the first point of contact for bumps + vibrations + bucking sensation. Head tube doesn't deflect much, but head angle and how top/down tubes attach certainly matters. A well designed front end deflects 3X more than rear. www.sheldonbrown.com/rinard/rinard_frametest.html
Also, different frame sizes on same bike model change stiffness.
Crazy to think that about 10 years ago bike manufacturers were all competing to make their bikes more stiff.
I agree that the front end is incredibly important for comfort. But that's a topic for another day.
Frame size plays a very small role when we calculate out the springs in a series - as I stated in the video, the overall spring rate is ALWAYS less than the softest spring - usually the tyres, sometimes the seatpost.
@@Cyclingabout "Frame size plays a very small role" = another oversimplification. An XS frame can ride a lot stiffer than XL on same bike model. That's why, in recent years, many bike companies have spent so much extra money $$$ on engineering and manufacturing expensive molds/layouts for each size with same parts.
That's incorrect. I've already explained why the vertical deflection does not change. Manufacturers change the moulds because riders of different heights and weights require different carbon layups to optimise the frame stiffness and strength.
I have a canyon endurance with flex seatpost.... but when it bends it changes the angle of the saddle..... I had problems with that, so I have a normal again now.... om my road bike that is but the 30mil tubeless tires give me a lot of comfort :)
and for my bikepacking vacations I orderd a santos crosslite with 50mm tires and rohloff/gates system hope to get it in 5-6weeks :) for my iceland trip this summer if I can go ad least
With flex posts, I've always accounted for the saddle angle by tipping the nose forward when no load is applied. But currently I'm using and loving the eeSilk post which stays flat as it goes through its travel - and I've been able to tune the spring rate to the level I prefer!
Congrats on the new bike! If you haven't used the Rohloff/Gates combo before, you're going to absolutely love it.
Confort=spring force? I think some other variable need to be add to conclude, your feet and your hand are on the bike too. Its not just a seat post thing
This video is about the role a frame plays in the overall bike comfort. Hand comfort is a function mostly of your handlebars and grip choice, but also the fork, depending on the terrain. Foot comfort... well, it's probably your shoes don't you think?
With this video we went waaay deep into the rabbit hole of geeky, in-depth analysis... I love it! Well done! It's been a long time, after many years of following bike tech, that I've actually learned something new! Interesting subject and approach!
Thanks! My next video should be a unique approach to understanding another characteristic about bikes that we take for granted. 😎
@@Cyclingabout question: Canyon now offers a flexing seat tube (e.g. on their endurance model), as a road racer should I consider this or definitely stick with the rigid seat tube?
@@JanTrenson For a road bike, it kinda depends on your riding style and what you prefer. I personally have a flex seatpost on my race bike and think it's beneficial. If you've ever dug into the "hysteresis losses of tyres" you'll know that lower tyre pressures can actually be faster when a surface has imperfections. (*Warning: the next section is extra-nerdy and currently theoretical because I don’t think people are testing this*)
That’s because the losses in the tyre sidewall/casing dominate until the "breakpoint pressure”, when then the "impedance losses" start to dominate. Adding a soft spring to the series (eg. flex seatpost) theoretically allows us to increase our tyre pressure past the usual breakpoint pressure, reducing the impedance losses in the system, and decreasing the overall rolling resistance.
Basically, if our understanding of "impedance losses" is correct, I think the fastest system has to be the one with vertical compliance built into the handlebars and seatpost. You can read more about rolling resistance and “impedance” here: blog.silca.cc/part-4b-rolling-resistance-and-impedance
@@JanTrenson Oh, and careful with the Canyon flex seatposts, they're particularly soft! You can see the seatpost data here: www.cyclingabout.com/seatposts-overlooked-yet-critical-for-cycling-comfort/
When I was young (17) I had a race bike with a Colnago frame made of Columbus Zeta steel tube (plus, as a side note, the first aerodynmic Dura Ace bike component set wih excentric pedals as a side, which was bloody expense for me at that time). My brother had a much cheaper bike with a much stiffer frame. Compared to riding my Columbus Zeta frame his bike felt as unforgiving as riding on a brick. I could feel this particularly when doing turns. My bike felt like it would snuggle into the curve radius. The sensation, and difference, was more than just subtle: It was tangible. Of course it all depends on the individual construction of a frame, not just on the material choice. However, steel is more elastic than aluminium, and if you build a steel frame and its tubes right, it will flex more than a similarly robust Aluminium frame. So there is material physics speaking in favor of steel comfort wise, as experience to back this up.
Just installing slightly larger tires and running a lower pressure will have a much more noticeable impact in ride quality that any slight deflection, be it frame, fork or seatpost, may have.
Yep! You can achieve very low n/mm values with voluminous tyres. But keep in mind that not all bikes have the clearance for wide tyres, so the other components should be kept in mind.
What about the deflection of a steel *fork*? It was my understanding that on steel frames that's where most of the 'give' comes from.
I should also clarify this video doesn't address another aspect of steel frames vs. other materials -- namely the differences in vibration-dampening properties:
web.mit.edu/2.tha/www/ppt/Bike-ISEA.pdf
@@peterbense5650 I thought this was covered and the answer was "negligible"?.
Geometry seems to most important. I have a straight carbon fiber seatpost(SADDLEpost?) and it has NO compliance, naturally. But it looks cool.
I do not find it negligible, in my riding experience.
Wow, that’s some great content right there, I learned something-I’ll be shopping for a new seatpost and I’ll hit your Patreon.
Many thanks!
I thought steel was standard on touring just because the repairability. I'd be more interested in a video on how many welders can fix aluminum. I heard aluminium is so common a material it is just as likely to find someone to do an emergency repair on a aluminum frame as it is steel. Modern steel bikes use such thin walls I heard it is more difficult for a welder to repair where aluminium tubes are pretty thick and easier for average welders to work with.
If aluminum breaks, you can in theory weld it back together, but in practical terms it's ready for the recycle bin.
The problem here is not the welding per se. Aluminum can be welded, but in order to achieve the desired mechanical properties the whole frame needs to be heat treated afterwards.
My brother held a couple of time trial records for many years and he has had every bike you can think of, but he will always choose a steel frame for long distances which are his speciality, the results speak for themselves over 40 years of competitive cycle racing at a high level, up to Commonwealth Games at one point. He said he might lose time in first half of race but in second half the fatigues sets in on other types of bikes, rider discomfort kicks in
Thank you, I've been saying this to steel snobs for a while. I like steel and ride it regularly, but riding to work there is a section of "cobbles" as well as lots of rail crossings. When riding that section, my aluminum bike shod with 28c tires feels like a featherbed compared to my steel bike with 25c rubber. When people start talking about frame comfort I always say that tires, bar tape and a nice chamois are infinitely more beneficial.
Those components make a really big difference. Seatposts too at the narrow tyre widths!
@@Cyclingabout that's now a component I will be putting more consideration into.
TODA LA RAZON
In my personal experience, tire size and pressure trump everything on vertical compliance in road bikes. Riding tubeless now, I can ride at a lower pressure with no performance penalty and dramatically increased comfort and stability.
A few comments:
• It isn't just the width of the tyre that makes a difference. Some brands of tyre aren't as compliant as others. Simply changing to a more compliant brand in the same size can make a huge difference. I bought a set of slightly used hand built road wheels from a friend who didn't like them, tried them out and I also hated them for the road buzz, then swapped the Contis they had fitted to some Michelins, and they were perfect.
• The choice of tubes can also make a big difference: latex tubes are more compliant than butyl rubber.
• Your video ignored the front end of the bike. The road buzz transmitted via the front wheel, forks, and bars into the hands can be a major factor in the perceived (lack of) comfort of a bike. Aluminium and carbon forks go straight from the crown to the dropouts, and the geometry doesn't allow for any give. Steel forks are generally designed with a curve in the blades, which allows the fork blade to flex ever so slightly. On a road bike, with skinny tyres, that fork flex can make a difference.
I totally agree that big tire and carbon seatpost are way more significant impacts in comfort, but over a long distance of riding Give me a choice of steel vs alu frame w/ similar cockpit and tires, I will always choose Steel. Plus When your standing on your pedals over rugged terrain, your seatpost deflection doesn’t matter, and depending on route that matters to more tired legs.
Even if you take the seatpost out of the equation, we still need to calculate out the 'springs in a series'. That's the frame which could be 7000N/mm, the wheel which is 800-1300N/mm and the tyre which is somewhere between 10-250N/mm. As I stated in the video, the overall spring rate is ALWAYS less than the softest spring. You, therefore, won't notice any difference between a steel and aluminium bike in terms of tired legs.
I like the part where you talk about bikes.
Adding heavy cargo significantly improves comfort. I once carried my big ass bluetooth speaker on the rear rack of my bike and the added 11kg clearly dampened most bumps in the road.
It did however make the ride quality much worse, because the high center of gravity is not fun to ride at all.
I'm really wondering how a bike rides if you put the full amount of cargo onto the rack that it is allowed for (25kg in my case)
Engineering knowledge highly suggest something. You talk a lot about vertical reflection but we just don't see aluminium reinforced buildings, or bridges made from it. Plus those are tubes - so forces don't work just vertically downwards.
What do you mean from comfort? Just butt related? With carbon or aluminium you need to check regularly for signs of breaking, rock chips or dents, corrosion. Look what brake cable can do around aluminium head of frame. That's why most of bikepacking bikes are made of cr-mo steel - you just can leave it outside on the rain (water) next go to the desert (sand dust/rocks/hot), later on winter crap (cold, salt, mud) and you don't give a f. Meantime precious frame made of Easton or Industrial Carbon went to fk itself. That's why it's easy to find 20 years old steel bikes going hard (they made aluminium bikes then) and it's almost non possible to find used 5 year old carbon bike (unless it's in prestine condition with stock brake pads and tires - means non used at all). Nowadays we are used to aluminium or carbon rims, frames to snap. I've seen snapped carbon frame like 2 weeks ago? And last time I've seen cr-mo frame to snap was like 15 years ago on some BMX dirt jump contest after HEAVY crash. Those materials are just for different purposes. I don't mind carbon on road bike, aluminium for xc racing but for daily commute or very long trips - steel is steel ;)
The point is not that frames don't deflect. They do. Maybe some steel frames flex at 4x fewer newtons per mm than other aluminium frames? But whatever the difference is, the vertical deflection of a frame is essentially meaningless when you calculate out the springs in a series - where the softest spring always dominates.
Please read this article: www.sheldonbrown.com/rinard/frame_fatigue_test.htm
The design of the frame makes more of a difference than the material. A frame must be designed properly to be strong, light, stiff, etc. The designer needs to choose the appropriate dimensions and structures for each material. Steel bikes don't last forever and yes they can break or crack and repairing them isn't as easy of cheap as people like to make it out to be.
All of us engineers know that deflection is based on a property called Young’s modulus. Steel is three times stiffer than aluminium of the same geometry. But geometry changes stiffness at a cubic rate. And aluminium is three times less dense than steel. Carbon fibre is all over the place depending of strand orientation and compressive or tensile forces. The best choice of all is clearly magnesium, which is why I have a magnesium frame. Happy days
In 2008 I picked up a Lapierre carbon frame and Easton carbon fork and parted over all my components from an aluminum Leader with a carbon fork, all the components were the same, wheels were Mavic Ksyrium, etc, and the ride difference was immediately noticeable. Not only could I feel the difference but you could hear it. The carbon frame has a quiet quality while the aluminum frame resonated into the wheels. No doubt the Alu Leader frame tubing was over sized and made it extra rigid, so was it the material or the tube size differences, IDK, but the carbon frame was an exponentially better ride. Not sure about the carbon long-term though, and starting to think it’s time to retire it