After watching this video I decided to put it to the test myself and can with absolute certainty say you are 100% correct! When I adjusted the front tire pressure I gained 5 watts in Zwift!
My main takeaway here is that, on tarmac, running the wrong pressure is only going to cost me up to about 3 watts, so I don't really need to be too precious with my tire pressure for everyday riding. Great vid, Ollie!
I tested this myself and agree that there isn't a huge difference over a wide range of pressures: th-cam.com/video/wB0o1gDUH80/w-d-xo.htmlfeature=shared
Great summary. We don't need super accurate gauges. Just get the tire at a pressure that gives you the most comfortable ride, and know that it's not costing you more than a couple of watts,
This whole exercise revisits the concept of Dunlop. He invented the pneumatic tyre at a time when tyres were solid. The result was a faster and more comfortable ride. Very high pressure pneumatic tyres effectively revert back to behaving like solid tyres. As with any suspension system the principle is to maintain tread contact with the surface being travelled over and this means keeping unsprung weight to a minimum whilst maintaining a well damped but highly compliant travel.
I just have to thank you for using the word "damped" instead of "dampened". It's amazed how many engineers these days say "dampened". Buy hey, both words are correct, like nuclear and nucular. Yeah...no.
As a mechanical engineer, I would welcome a next GCN video with an interview to the designer of this test rig. Some of the questions I would suggest are: 1 - only the rear wheel sits on the drum, whilst in the real case both wheels roll over the road, how do you factor in the resistance from the front wheel? 2 - How do you estimate the power loss? The only viable way I see is to get it as the difference between the power input by the cyclist at the cranks and the resisting power at the drum. However, when we talk of a resistance as small as 20 W, the accuracy of the two powermeters becomes crucial. Ollie: it's not a matter of the sampling frequency (Hz) that matters, it's rather the accuracy of the sensors. If the accuracy is 1% of the range and the range is, say, 2000 W, or maybe even just 1000, it's AT LEAST 10 W uncertainty at each one of the two powermeters, so the total uncertainty is more or less the same as the power loss to be measured, for the good tyre at least. 3 - again assuming the power loss is obtained from the difference between the power input at the cranks and the resistance at the drum, do you remove the effect of the aerodynamic resistance arising from the rotation of the drum?
Silverstone uses the Body Rocket pedals, which are accurate to 0.1% across the functional range. So Ollie shouldn’t have been dropping those 1 watt claims at the end, but otherwise he was OK.
The cycling world is full of claims with these exact questions. When you question them they just say you're too stupid to understand the testing procedures. We have a word for it down south, its called snake oil.
My guess by looking at how the bike is fixed at the fork is that the measurement is done at the front hub, by how much the whole bike is pulled backward by the rolling in-efficiency, which is generated then by the sum of rolling resistance, drivetrain resistance and a small other factors probably neglectable…
Literally minute 3-6 explains all this. Fml. Most of what you’re writing has already been well known a long time. They change one variable at a time which gives the difference. The whole system is measured and they are not using commercially available power meters - it’s lab grade transducers and strain gauges. By the 7 minute point this is all apparent. It’s as good a system of tests you’re getting. It’s not a wind tunnel. It’s simply for the non-aero factors.
I would assume that they're just trying to gather data for comparisons. Even though it's not a perfect test relative to real world riding the rolling resistance data comparisons between different pressures and tires should remain true.
Facts you need to know, about the right pressure😊😊: Once I crossed Australias Outback (5678 km). On the first day on my mission, using a steel MTB bike and a Yak trailer, starting from Adelaide (arrived by aeroplane from Denmark), I only did 37 km…!!!👀👀 Maybe the many hills on my way out?? The next day I did 77 km. More, but it was far too little! I NEEDED to cover 130-256 km/ day, in order to reach each tank station, with water supply and camping, along the road. The 3rd I did 116 km. More, BUT still toooooo little! From the 4th day and onwards I would be out in the Outback. I NEEDED to cover up to 200 km/day. Had I overestimated my own capabilities? Was close to cancel the mission across up to Darwin. THEN I checked the tyre pressure…..I was WAY TO LOW!!! I pumped up to the maximum for the tyre (4,5 bar). The next day I left for the Outback. I did ride SOOO easy and fast!!👀👀👀😁😁😁🚴🏻♂️💪🏻😊 I even had time for a siesta by noon. And I arrived well in time before darkness, having done 180 km👀👀👀👀😃😃 After this, I checked the pressure EVERY single day. Constantly. By getting the right feeling using my weakest finger. Morale: Always the right pressure. Always! You will be rewarded!!🙌🏼🙌🏼🙌🏼🙌🏼💪🏻🚴🏻♂️😊😊😊😁😁
17:00 you shouldn't forget that tires at 2 bar tend to drift much more in corners. The testing rig, while very well designed, doesn't take this into account. And don't forget that while you're not bottoming out on that test rig, pro riders in a peloton, hitting a rock at 55k/hr, will have a much higher chance bottoming out.
I understood it that when you lose 95 Watts at four bar, you lose "another" 74 Watts at two bar, meaning in 169 Watts in total. Totally agree that 2 bars only worked in this specific lab set-up. On the road it would feel all squishy, your tyres would slip away when cornering even at low speed and the tiniest bump would make the rim hit the road surface.
Agree. I love to corner very hard and I always preferred a higher pressure just to keep the tires from feeling like they were rolling off the edge of the rim. Straight and flat efficiencies are good to know but the world is a lot more dynamic than that.
@@einundsiebenziger5488No it's only 74w at 2 bars. We shouldn't forget that tire is air pillow. High pressure makes it sturdier and bouncier while lower pressure makes it softer and floatier. If you go through rough terrain do you want to float over rocks and sticks or do you wanna bounce on them?
@@MrTandtrollet Especially on the front. You can ride out a back end slide, but a front end wash out, can leave you picking debris out of your face. LOL
This is a really interesting subject and as an engineer I find the test rig set up fascinating. I agree with lower pressures being more efficient on a rough surface but in a real life situation which includes climbing, sprinting and descending I don't concur. I'm in the Alps presently running Vittoria Corsa 28mm tubulars on Dura Ace 28mm wide rims and set the pressures to the Silca calculator which was 5.4 / 5.25 for my weight 72kg. This is great on the valley roads but climbing out of the saddle was too bouncy and descending and cornering fast around the hairpins was sketchy as the back tyre was slipping. Yesterday I increased the pressure to my normal 6.2 / 5.8 and the bike felt like it was on rails cornering and climbing felt so much more efficient. I know it's difficult to replicate these conditions on the rig but the results are a good starting point but everyone should tweak them for the terrain and conditions.
I am very wary running too low on fronts. Back slipping is bad enough but I have had near wash out of the front when i had a leak that was dropping the front pressure until it was scary in the corners. I had to stop and pump back up until home. Downhill into a hard corner on soft fronts is not fun. I think the data is interesting, but point to finding ones best balance of f actors. - Cheers
I dropped my pressures to 4.5 bar front, 5 bar rear 28mm and did a ride past Silverstone. For me, no faster but felt a lot nicer, easier. By the way. Have also been experimenting with a thin layer of talc between butyl inner tube and tyre casing to see if that reduces internally induced rolling resistance. I think it might do...
To my knowledge, Pogačar routinely rode 30mm Conti tyres on fat, tall Enve aero rims for this year's Tour win. Although his body weight is very low which makes that counter-intuitive, of course his average speed is a lot higher, plus the aero gains when he attacks off the front become far more significant with that combination. Re: your comments about best tyre pressures on cobbles Olly, don't forget that most of Paris-Roubaix is ridden on tarmac or concrete slab, so the tyre pressures the Pros ride are necessarily a compromise between the rolling resistance on all those surfaces. Finally, of course we all wince at the thought of 70s Pros riding 23mm tyres in the very same race, but then they rode skinny, very shallow aluminium sprint rims for tubs, and there'd have been a lot of deflection and shock absorption going on within those rims, plus much looser spoking, also the forgiving steel frames and forks of the time. But for sure, the ride would have been harsher. Nice piece though Olly, fellow Physics nerd here!
Flexy rims and steel frames might reduce a bit of road buzz but there's absolutely no way they'd soften something as significant as Roubaix cobbles. Pogacar's tyre pressure is not really relevant to recreational riders doing half the speed at best. It's like comparing an F1 driver's tyre choice to the cheap rubber for my 1.2 litre hatchback.
I disagree over the steel frames/forks and thin aluminium flexy rims, as well as the much looser spoking from those times. These would all, together, have had a softening effect on cobbles, although not as much as the much larger tyres used these days. I'm just making the point that you can't simply compare tyres now and then, its not that simple. The entire bike "system" was different, you take it as a whole. Modern carbon fibre bikes can be made with more flex, but for big, instant impacts steel is very absorbent. And Pogačar's tyre pressure IS relevant to me. I ride a Colnago, I ride Schwalbe Pro One Tubeless 30mm, and although I'm in my mid-60s I can still average Evens on my own, and faster in a group. I get the same big tyre benefits as him, with perhaps 0.5 bar higher pressure because I'm fatter than he is, but I get those same rolling resistance gains. He'll of course get more from them aero gains than me, because he goes a lot faster than me. Thanks. @therider4909
Might want to change the title. I thought this was a clickbait type video with nothing useful, but I watched when I saw the runtime and I am glad I did, always love good testing.
So the title is NOT click bait, but because you thought it was they should change it? Wouldn't that make the new "changed" title click bait to attract people who mistakenly think the original title is click bait? lol
@@space.youtubenope because it sounds like an ad, which it is not. He’s suggesting changing to a title that doesn’t make it sound like an ad for some product
I agree, the title and the picture don't give the feeling that the video will be very interesting. And yet it is nicely done, with such a good scientific test. If it wasn't a GCN Tech video, I would not have try to watch it
@@KelvinSuddith You think the title of this video sounds like an ad? What sort of product, in your imagination at least, do you think the title of this video would be trying to introduce? It literally states what's on the tin and you people are aren't happy? lol Some people just like complaining I guess. Ps I don't think you understood my original comment, but thanks for trying all the same. 😁
Great video. Just to add, on Arenberg alone the system takes approximately 23000 hits (2300m x 5 cobbles/m x 2 wheels). Within those 23000, it's the random missing or proud cobles and wide gaps that are the problem.
The system doesn't take 23000 hits. You often don't hit anything for a full meter with either or both wheels. At 40k/hr you fly over a lot of those cobbles.
Possibly the best cycle science video I have seen. Vindicates my view that a lot a cyclists inflate their tyres to high. 65 to 80 psi is a good median for most terrain.
Plenty of bike shops have been guilty of this as well. I recall buying a few bikes, and them pumping the tyres up to over 100psi - despite me asking them not to. Got home and let the tyres down to a proper pressure.
If bike shop people were super smart, on average, let's be real, they would have had a different career. Cycling is also a world that's resistant to change.
@@stevengagnon4777 No they wouldn't. The dentist coming in to buy his pinarello or cervelo wasn't thinking you were smart. Bikes are simple as fuck too - you can build a bike from scratch in a few hours. Now, of course, perhaps the average member of the public who goes to a bike shop can't remove the back wheel so maybe he or she thinks it's an incredibly complicated mechanical device and you're a genius or something, but you'd be a fool to measure yourself against them to give yourself the impression you're highly skilled. if you spent 4 decades doing bike maintenance you wouldn't learn anything new after the first 2 or 3 weeks.
This rig looks ideal for comparing the performance of an old school tubular with a TLR. For example, the Pirelli P-Zero is readily available in both formats in size 700 x 28. I would expect the casing material and layup to be identical too. Of course the big difference is that the tubular will have 30% more usable casing making it much more compliant and comfortable at any given pressure not to mention almost impossible to pinch flat. Also, one would expect the tubular to handle a much wider range of pressure especially on the low end owing to the flangeless rim profile.
Tubeless will be better than the tubular. There is a reason cars don't use tubes. Tubulars, despite their name are just constructed with a built in inner tube and that layup will have more internal friction reducing compliance at a given pressure. Tubeless tires only have the casing flex to tune.
Interesting stuff. As a recreational road cyclist though I don't dive this deep into the setup. 5.5 to 6 bar pressure on 28mm tires is all I need to know good to semi good roads.
I'd like to see more about tubeless tyres and inserts and how they affect handling and puncture resistance. The drift that I get on my tyres with a foam insert is very much like the feeling I got with high-quality CX tubulars. There's a drift, but it's controllable. You don't want that on the road necessarily, but it feels good on gravel bikes. But I think there's a lot to be done there. High quality TPU tubes are nice I guess, but they're still a tube and I feel like that has very specific drawbacks that most riders and unsupported racers shouldn't have to contend with.
Fascinating and well researched test (given the constraints), very well presented by Ollie. I need to lower my tyre pressures 🙄. More of these please GCN.
In other words, on tarmac: it will depends of the type of tyre, rider weights, and pressure to get more or less 3 watts. I'll continue use my 80 psi (between 6 and 5 bar) and it will not going to affect my super 195-205w on average rides.
Actually there a different kinds of tarmac and silcas excellent calculator also account for this. But of course the calculator depends on the values you enter. Looking at graphs showing coalition between rough/average/smooth tarmac and tire pressure shows the penalty from to high pressure is significantly higher vs the penalty riding with to low pressure.
Such a high quality video! I love that Pirelli have been putting such a massive investment into this. I absolutely love the Pirelli Gravel H tires on my gravel bike. They roll so good on gravel and surprisingly well on pavement too. It would be fun to see how they compare to other tires and at different pressures.
I don’t think the pros can go lower; the cobbles at Paris-Roubaix are totally different! This drum simulates „urban“ cobbles with a relative regular pattern - at P-R you have random stones and the wheels are hitting steps up to 5 cm and more. On that you will get pinch flats much easier
Ollie, geeked out to the max! LOVE IT!!!! Ask the lab nicely if you can go do some of those other test protocols you mentioned. I. for one, will be glued to the screen!
My first mid-end road bike, long ago, had 1.25-inch (32mm) tyres, with a recommended pressure of 60 psi (4 bar). When I got some money, I switched to 20mm sew-ups running at 125 psi (8.6 bar), and the decrease in resistance and increase in speed were dramatic. Today I ride 23mm clinchers at 110 to 120 psi (7.6 to 8.3 bar). Sorry, I'm sticking with "old school", never going back to fat, soft tyres. Those are for paperboys. Yeah, I know, Tadej goes big and squishy and wins everything, but I suspect the advantage he has over me is probably down to something other than tyres.
You just feel like you are going faster due to the vibrations, time yourself 5x on higher and lower psi on long rides and get back to us. Maybe you are heavy, in which case 120 could be your optimum.
These numbers refer to his body weight, while he also is running tubeless. If I do that on my clinchers which have to support my 95kg, I would have a flat within 10km.
So in summary, for most of us plodding along at 25-30km/h on reasonable (but occasionally pot-holed) tarmac, tyre pressure makes precisely 2 parts of f**k all difference LOL. Besides, this test takes no account of the losses through the front tyre, nor does it consider what happens when you hit a pothole. I think I'll protect my carbon wheels by running the tyres a bit on the high side, plus I'll maintain some grip while cornering hard without the tyre rolling off the rim!
Thanks for making this video showing other people what I have known since I was 8 years old. Even at the ripe old age of 8, I was racing my bike against other kids in my neighborhood, and learned that keeping my tires pumped up made my bike roll faster. What exactly is the right pressure for your tires? I usually start at above the recommended pressure on the sidewall of my tire, and I ride the bike every day. As the days pass, the pressure decreases, until the tire becomes soft. You can run the pressure again, and as they days pass, you can figure out what is the optimum pressure for your tire, your weight, and your roads. On that day or days where you get the best performance, check your pressure, and pump up your tires to that level before every ride.
On finding optimal pressure, an industry professional said* to "search for smoothness". When you feell the vibrations, it's too high. But much lower than that isn't great, either. *) It was an interview with the less mainstream and less performance oriented chanel "the path less pedaled" (home of "partypace"). I think, Ollie and another presenter have met Russ and Laura on a shoot on some mountain this year or so.
For myself, I would be wary of running too low on the front tires, as it tends to wash out the front end in hard cornering. Over all good data is good to have, and can lead to the sweet spot. Different set ups for different conditions, seems like a normal way to look it things. Always interesting content. - Cheers
I have been riding MTBs and roadbikes since 35 years, even rode some competitions and countless alpine passes and granfondos all over Central and Southwestern Europe. Always pumped my tyres to the point they "felt fast", which may have been all wrong. I don't care, because the only point I did not enjoy a ride because of tyre pressure was when it suddenly went to zero - aka I suffered a flat. If you do not make a living by racing bicycles, there is no need to overthink this, just pump your tyres and go for a ride!
I used to ride our local century on my FWD recumbent with a 24"x1.375" width Cheng-Shen commuter tire on the driving wheel. Didn't need to pump up it to 80 psi, and it was more comfortable at 60 psi. This was on average US spec tarmac with all sorts of local differences in quality, from being less than a year old to 20 year old weathered/old tractor tire washboarding and pitting.
You actually don't. One thing about "science" is you always start with a wide a difference as possible to make sure you can actually measure something of value. If they would have gone in with a GP5000 and a superfast tire, there may not have been much to talk about or worse yet, the wrong conclusion.
Hey Olli, just to make sure: When you compared results to the SILCA website you put in the "measured width" of the tire at 28mm. While I do not have the Pirellis for comparison, my 28mm Schwalbe Pro One TLEs for example are actually 31-31.5mm wide (hookless rims). The difference in recommended pressure acc. to SILCA is a full 1 bar compared to a tire that is really only 28mm wide.
I used to run 23mm tyres on cobble at 7 bars, for my commuting through Paris and her suburbs. It's shaky, but you simply get used to it. :) I run 28 at 6 now, and it's already a smoother and more efficient ride, even as an amateur. As you mentioned, however, in a racing situation, it's easy to conceive how different the mindset and savings would be.
I noticed the front end was rigidly fixed with no wheel or drum. This DOES have a huge effect. Would LOVE to see the test rig with a front wheel setup. In the days before my spinal prolapse ended my riding, I played around with this. Different width/pressure tires on the front (Keeping the back fixed) had a noticeable effect. I was running Conti 4000'''s 21/23/25.. Nowadays I potter along on my flatbar roadie and Schwalbe Mrathon at 60-70 psi, so it was interesting to see maximum comfort probably equals maximum efficiency. I think I'll go down another 10 psi. Thanks. informative video.
2bars on 28c for a Roubaix or even average hard cobblestone has one huge problem… That the drum doesn’t recreates! The usual Potholes and protruding cobblestone odd edges every 10m-20m. Great content as often on theese topics !
"96% of Cyclists Get Their Tyre Pressure Wrong. How To Get It Right" Step 1. Build a multimillion pound rolling road facility Step 2. Test every type of tyre at every possible pressure on every possible surface Step 3. Let a bit of air out of your tyre Seriously though, the video was much better than the title - good info!
Great Video! Sounds like you definitely need to go back and do all the tests you need to, all the sizes, all the pressures etc. I have no idea what this would cost you but I'm sure all the viewers including yourselves would greatly benefit from a update video with all the intel you will discover.
That is standard advice, but without a rig testing both tyres at the same time its hard to know if its the correct policy. Seems legit due to less weight over the front, but the arms act as shock absorbers unlike the lower body effectively reducing weight on rough surfaces? So who knows for sure, maybe it should be 10psi lower?
@@benedictearlson9044 In addition to the rear weight bias, my theory goes like this: 1) A softer front tire is more comfortable and reduces numbness on long rides. 2) I’m less likely to get a pinch flat on the front because I can more precisely absorb or avoid hard bumps, and 3) I can avoid road hazards such as glass better with the front tire compared to a back tire.
Running lower pressure in the front tire is for comfort and traction. Every thing is a trade off, if you want the least resistance High pressure and the smallest contact patch are the your friends, if you want a less fatigued rider, that five PSI lower is nice. Every ones riding style is different some crazy people can handle rattling their brains and a few of these riders may even have uncanny bike handling ability, these are the ones that seem to walk away from other riders when the going gets rough. A more aggressive tread pattern on the front, if necessary rear too, coupled with a narrow width, has less resistance than an under inflated wider tires. Question is are you the type of animal that can take all that punishment? For one race fine, for the season???
When GCN applies Peer Pressure: "96% of Cyclists Get High Blood Pressure when they get Their Tyre Pressure Wrong . . ." Slow Leaks: 😉 Local Priesthood Cycling Club: "Pray Sure!"
Definitely true for the time I used a pressure gauge in addition to that on my floor pump. Re-adjustment of pressure took time, effort and ruined my mood. When the gauge was not working properly at one time, I smashed it on the ground, completely destroying it. I never replaced it and using just the gauge on my pump leaves me a much happier cyclist now.
This is fantastic stuff! The competitive cycling world is at a ridiculously high technical level these days. For all the miles of pro cycling I watched this summer it kept me interested. The advanced tech in cycling did that! However on my bike a universe away it’s a enjoyable physical pastime.
It seems like you want the pressure low enough and tire size large enough to absorb the average road bump size, say 1 cm, plus a little firmness for the big bumps without bottoming out. And if the road is only bumpy for a portion of the ride and smooth for the rest, then you want to increase pressure a bit to balance out the efficiency of high pressure on a smooth surface. The trick is to find that balance point, approximately.
Or go to 18:06 and pause if you're in a hurry. I think I'll try 80 psi (5-10 psi lower) on my next ride and see how it feels. No mention of whether tire pressure should vary front to rear. Early 80's it was 105 psi with 20 width. Times have changed!
awesome video as usual, kudos. In regards to the wider tire, if you’re putting a wide tire on a rim that’s designed for a narrow tire when we talk about optimal fitment of course it’s going to be slower. It would’ve been interesting to fit a wider tire on a wider rim that is optimized for that tire size.
I use bicycle everyday for my transport, and a lower tire pressure made the bike easier to roll and controled. I don't feel any bouncing feeling on the tires.
It gets faster and faster! First it's one Hertz, a second later it's two Hertz, then three Hertz. Soon you can hear it. Ride long enough and you can see it it.
Don’t forget that the front wheel is seeing pretty close to the same loads etc. So a set of nice tires! Were the testers including the “load” of the front in their watt calculations.
Love this nerdy content; please keep it going if you can! I'm currently running 32mm tires with TPU tubes on my road bike. According to the Silca calculator, I should be running my tires at 4.5 Bar (65psi) on paved surfaces. That's actually very squishy in my opinion. Instead, I run 5.5 Bar (80psi), which seems to be ideal: comfortable, smooth, but it doesn't feel like I'm riding through thick sand. OK, I don't actually run 80psi all the time. Most of the time, I'm not even sure what my tire pressure actually is. When I inflate my tires, I go up to 90 psi, sometimes even up to the recommended max of 100, and then don't mess with them for 2 weeks or more. The tires lose a couple of psi a day. For the first couple of days, they're honestly way too hard, sort of bouncy, which isn't good, but then they feel fine, and when they finally start to feel too squishy, which is at about 70 psi for me, I start over.
Bad practice. Should just inflate tires before every ride. Just aim for between 60-80 or pumped before every ride. Tubeless tires lose a lot of pressure every day, very unpredictable
This was fascinating. Keep heading back! It'll be like Alex Dowsett testing everything he owns in the wind tunnel which was full of surprises (and even generated a product for Nopinz)
My hookless rims have a max pressure of 45 for my 35mm summer gravel tyres and a max of 40 for my winter 42s, honestly I can't tell the difference but I've not done any personal testing, I usually run 5 psi under at the rear and 3-5 less at the front and it's all been hunkydory, might drop it a bit and see if there is any discernable difference 🤷
Gravel tyres seem to avoid the problem that road rims are having. My road bike has 28mm and there seems some concern with tyre blow outs due to narrow rims. Haven’t had an issue yet but lots of stories of issues. Argghhh
Intriguing to see how much the chain and derailleur bounced around on the simulated cobbles. That definitely reduces the efficiency of the drive train!
Ollie asked how they managed Paris-Roubaix on 23mm tires back in the day. Well, they had much more forgiving steel frames and forks, and 28mm tubulars on light aluminum rims that were 10x as forgiving as wide and deep carbon aero wheels.
In the steel-frame era they rode on 20- to 22-mm tubulars pumped to the maximum allowed pressure. Indeed the flat box-section alloy rims factored in, it's only a few years ago that pro teams put these on bikes especially for Paris-Roubaix when they would usually ride deep-section carbon wheels for everything else.
Many used Paves for the Roubaix...I used Paves all the time . Switched to 26 mm to 28 mm tubulars in the early nineties...I was heavy so it made everything better.
Well, I think they had way more punctures, too. It was routine for riders to have multiple punctures and still win, which is pretty rare today. (My recollection is that when Hinault won in 1981 he had 4 punctures and 2 crashes, or vice-versa.)
@@rkentwenger5095not nescesary, riding on cobbles is more technique than you think, arenberg is an exception, but every cobbles pave has a ridge, ther where you would preferably ride. And every section has his own few golden speeds. On this speeds you fly from one ridge to the other. A little faster you jump more, a little slower the same. You see it even in action when Alex was riding 35 km /h he was in discomfort. When he slowed just a little the vibration was smaller. At even slower speeds, he vibrated more,….. High tire pressure gives puncture resistance, it is total system, material choices matter
@@einundsiebenziger5488 as you mentioned the flat box section rims ( that I still use) made a big difference. They were relatively strong ( stronger and much lighter than clincher s) and could be easily tuned with spoke count, rim weight. spoke guage and tension. Being flat and wide they had good vertical compliance and good lateral stiffness. They really are a joy to ride and thanks to the acceptance of and availability of wider tires in tubulars , even better. I always rode paves anyway but the newer tires certainly give superior puncture protection. Those tubulars were also made from cotton which also softened the ride and for that special day with absolutely no rain in the forecast there was silk . Even at 100 kilos I could ride a 330 gram rim with 32 skinny double butted spokes will alloy nipples and a decent 23 mm training tubular up front ( being dishless made it possible) and as long as I didn't hit an immovable object they were plenty strong for daily use. Once I discovered Paves and those wider rims I never went back . The ride and confidence in the twisties was awesome.
Very interesting. This is the best drum testing I've seen and probably the closest to roll-down tests (e.g., Jan Heine's stuff). The whole-system approach is much more important than simple small drum testing of just a wheel, for example it is likely that most of the power lost on rough surfaces is dissipated as heat in the riders body. I look forward to many more results from this kit!
I know everyone likes to think there is a chart they can refer to and not think about it any more, but jeeeeez. There is one easy way to get the right pressure for a road bike -- on the day of your ride, ride a bit on the route you are taking, starting with obviously too much pressure, and slowly reduce the pressure until just the road buzz goes away. It accounts for everything -- your bike, your body, your tires and tubes, the road, the weather, etc. If your route has wildly varying surfaces, either adjust as the terrain changes, or decide which section you want to accommodate.
Back when I was younger, as soon as I could afford it I got a full-suspension mountain bike with rear and front suspension that were good enough to handle jumps beyond what I myself felt safe performing, and always kept the tires at the maximum pressure allowed to reduce the odds of sharper bumps or hard landings pinching the tires and hitting the rims, to maximize the life of the rims and reduce the risk of cutting into the tires with the the rims, leaving the suspension to take care of making it a smooth ride (it was always a bit of a tense moment pumping the tire to the limit if I didn't had my mind elsewhere and instead remembered there was a chance the tire might happen to not handle the pressure anymore and would explode this time; never had an explosion though, but I always bought reasonable quality tires, so it wasn't worse case scenario)... I have no idea whether that was the best thing to do, but it's what I did.
Interesting results. I would love to see more testing to understand the road surface, pressure and tyre width combination better. And I would love to see actual gravel testing instead of cobbles but that cannot be done on a drum.
Not gonna lie, those reflective stripes on the cheap Amazon tyres actually looks pretty cool and is a pretty innovative way to add some retro-reflectivity to your bike at night.
@@SebastianTominecit's definitely an underrated tire. The small loss in rolling resistance is well made up in real world riding...especially in the wet and cold weather of both spring and fall. It doesn't necessarily have to be wet as they will give better grip on dry and cold roads too. I would like to see more tires with actual treads too ... I don't believe that slick tires are good for all around real world riding. Especially since the acceptance of the wider tire.
Remember a bike has 2 wheels and although the front wheel losses are likely to be different from the rear wheel losses, as an example, times the losses/gains by 2 and the magnitude of the effect becomes even more significant. Always amazed me in kids triathlons, which bike events are often run over very bumpy grass and parents who were road riders, would have their kids tyres pumped up super hard, poor kids!
Couple of things. First one, if pressures are this important, what is the most accurate and CONSISTENT way we should measure our pressures as normal riders at home? What's the go-to gauge for measuring? I'm going to guess if I took 3 different floor pumps, couple of mini pumps, my air compressor, etc, they'd all read differently. Second one, pros are drilling cobbles at way faster than 35k/h, their pressures are different than us noodling around. Plus some of those classics riders are heavier (most are). Thirdly - Dylan Johnson has been saying for years pros should be on 40-50mm wide tires for the cobbles, no one will do it, but after seeing this data, it's something to consider (different bike frame of course).
For the third point, maybe for cobbles that is the best option but most races with cobbles have significant amounts of smoother surfaces so mid 30s is probably the right way to go for them. I agree with your first point though, normal people just have to go off a track pump or something and kind of see if it feels the right pressure.
@@_Tp___exactly what I was thinking. tire choice has to consider the tarmac and cobbles. If you just take a 50mm tire to monster truck over the cobbles, then yeah it will be faster but on the tarmac the rider would suffer and be much slower than the group riding 32’s or 30’s
GCN made that video, a mountain bike, with mtb tires, is faster across the cobble sector. The thing is Paris Roubaix is a race mostly on regular roads.
Videos like this really get me excited! I’d love the chance to visit test facilities like this myself (especially alongside Ollie). If slightly heated tires offer performance benefits, do you think we might see 'tire warming' technologies in the future, allowing riders to start with optimal tire temperatures from the get-go?
Going on longer rides, say over 50 miles and beyond, I really enjoy the 30mm hook less tubeless tires (70 psi) it saves on the sit bones and hands from the pristine asphalt we have here in Minnesota. The lower pressures I can run and not worry about pinch flats are worth it. I had 25mm tubeless that were at 100 psi and it would shake your teeth out.
This is what the majority of pro's are now riding, just 28mm, hookless tubeless. Maybe higher end rims and tires than you perhaps, but if you look it up this is now pretty much the norm. Completely different than just a few years ago.
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¡Gracias!
Gracias a ti por tu apoyo! ❤️
If I lost 95 watts I'd be going backwards 🤣
😂
:nod:
😂😂
Me too ! ! ! ! !🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣
If I lost 95 watts Id brag that I once had 95 watts
After watching this video I decided to put it to the test myself and can with absolute certainty say you are 100% correct! When I adjusted the front tire pressure I gained 5 watts in Zwift!
lol
hoohoohoo
😂😂😂
What about the rear?
@@cotillion1687 It's flat, leaning up against the wall. 🤣Bike is attached to my Tacx Neo trainer.
My main takeaway here is that, on tarmac, running the wrong pressure is only going to cost me up to about 3 watts, so I don't really need to be too precious with my tire pressure for everyday riding.
Great vid, Ollie!
I tested this myself and agree that there isn't a huge difference over a wide range of pressures: th-cam.com/video/wB0o1gDUH80/w-d-xo.htmlfeature=shared
but it will fuck up your comfort?
Equally swapping tyre width doesn't really make much difference. I got 28s rather than 30s because they were on sale. Looks like the right choice!!
Long term 100km ride that 3 watts is gonna show in time an pace but no matter
Great summary. We don't need super accurate gauges. Just get the tire at a pressure that gives you the most comfortable ride, and know that it's not costing you more than a couple of watts,
This whole exercise revisits the concept of Dunlop. He invented the pneumatic tyre at a time when tyres were solid. The result was a faster and more comfortable ride. Very high pressure pneumatic tyres effectively revert back to behaving like solid tyres. As with any suspension system the principle is to maintain tread contact with the surface being travelled over and this means keeping unsprung weight to a minimum whilst maintaining a well damped but highly compliant travel.
I just have to thank you for using the word "damped" instead of "dampened". It's amazed how many engineers these days say "dampened". Buy hey, both words are correct, like nuclear and nucular. Yeah...no.
As a mechanical engineer, I would welcome a next GCN video with an interview to the designer of this test rig. Some of the questions I would suggest are: 1 - only the rear wheel sits on the drum, whilst in the real case both wheels roll over the road, how do you factor in the resistance from the front wheel? 2 - How do you estimate the power loss? The only viable way I see is to get it as the difference between the power input by the cyclist at the cranks and the resisting power at the drum. However, when we talk of a resistance as small as 20 W, the accuracy of the two powermeters becomes crucial. Ollie: it's not a matter of the sampling frequency (Hz) that matters, it's rather the accuracy of the sensors. If the accuracy is 1% of the range and the range is, say, 2000 W, or maybe even just 1000, it's AT LEAST 10 W uncertainty at each one of the two powermeters, so the total uncertainty is more or less the same as the power loss to be measured, for the good tyre at least. 3 - again assuming the power loss is obtained from the difference between the power input at the cranks and the resistance at the drum, do you remove the effect of the aerodynamic resistance arising from the rotation of the drum?
Silverstone uses the Body Rocket pedals, which are accurate to 0.1% across the functional range. So Ollie shouldn’t have been dropping those 1 watt claims at the end, but otherwise he was OK.
The cycling world is full of claims with these exact questions. When you question them they just say you're too stupid to understand the testing procedures. We have a word for it down south, its called snake oil.
My guess by looking at how the bike is fixed at the fork is that the measurement is done at the front hub, by how much the whole bike is pulled backward by the rolling in-efficiency, which is generated then by the sum of rolling resistance, drivetrain resistance and a small other factors probably neglectable…
Literally minute 3-6 explains all this. Fml. Most of what you’re writing has already been well known a long time. They change one variable at a time which gives the difference. The whole system is measured and they are not using commercially available power meters - it’s lab grade transducers and strain gauges.
By the 7 minute point this is all apparent. It’s as good a system of tests you’re getting. It’s not a wind tunnel. It’s simply for the non-aero factors.
I would assume that they're just trying to gather data for comparisons. Even though it's not a perfect test relative to real world riding the rolling resistance data comparisons between different pressures and tires should remain true.
Facts you need to know, about the right pressure😊😊: Once I crossed Australias Outback (5678 km). On the first day on my mission, using a steel MTB bike and a Yak trailer, starting from Adelaide (arrived by aeroplane from Denmark), I only did 37 km…!!!👀👀
Maybe the many hills on my way out??
The next day I did 77 km. More, but it was far too little!
I NEEDED to cover 130-256 km/ day, in order to reach each tank station, with water supply and camping, along the road.
The 3rd I did 116 km. More, BUT still toooooo little!
From the 4th day and onwards I would be out in the Outback. I NEEDED to cover up to 200 km/day.
Had I overestimated my own capabilities? Was close to cancel the mission across up to Darwin.
THEN I checked the tyre pressure…..I was WAY TO LOW!!!
I pumped up to the maximum for the tyre (4,5 bar).
The next day I left for the Outback. I did ride SOOO easy and fast!!👀👀👀😁😁😁🚴🏻♂️💪🏻😊 I even had time for a siesta by noon. And I arrived well in time before darkness, having done 180 km👀👀👀👀😃😃
After this, I checked the pressure EVERY single day. Constantly. By getting the right feeling using my weakest finger.
Morale: Always the right pressure. Always! You will be rewarded!!🙌🏼🙌🏼🙌🏼🙌🏼💪🏻🚴🏻♂️😊😊😊😁😁
17:00 you shouldn't forget that tires at 2 bar tend to drift much more in corners. The testing rig, while very well designed, doesn't take this into account.
And don't forget that while you're not bottoming out on that test rig, pro riders in a peloton, hitting a rock at 55k/hr, will have a much higher chance bottoming out.
I understood it that when you lose 95 Watts at four bar, you lose "another" 74 Watts at two bar, meaning in 169 Watts in total. Totally agree that 2 bars only worked in this specific lab set-up. On the road it would feel all squishy, your tyres would slip away when cornering even at low speed and the tiniest bump would make the rim hit the road surface.
Agree. I love to corner very hard and I always preferred a higher pressure just to keep the tires from feeling like they were rolling off the edge of the rim. Straight and flat efficiencies are good to know but the world is a lot more dynamic than that.
Yeah, conrnering with low pressures is how you end up in a ditch!
@@einundsiebenziger5488No it's only 74w at 2 bars. We shouldn't forget that tire is air pillow. High pressure makes it sturdier and bouncier while lower pressure makes it softer and floatier. If you go through rough terrain do you want to float over rocks and sticks or do you wanna bounce on them?
@@MrTandtrollet Especially on the front. You can ride out a back end slide, but a front end wash out, can leave you picking debris out of your face. LOL
Ollie at his best. Totally geeking out about the test machine and its results. And me? Glued to the screen and just loving it!
Not only is Ollie at his best, he is the best GCN staffer for this kind of data intensive tech testing.
I'm under a lot of pressure, but I'm still rolling with it! 🚴♂️
This is the comment I was looking for. Congratulations!
Congrats then 😂
must be rather tiring
😅😅😅
Like most of the internet, full of air.
This is a really interesting subject and as an engineer I find the test rig set up fascinating. I agree with lower pressures being more efficient on a rough surface but in a real life situation which includes climbing, sprinting and descending I don't concur. I'm in the Alps presently running Vittoria Corsa 28mm tubulars on Dura Ace 28mm wide rims and set the pressures to the Silca calculator which was 5.4 / 5.25 for my weight 72kg. This is great on the valley roads but climbing out of the saddle was too bouncy and descending and cornering fast around the hairpins was sketchy as the back tyre was slipping. Yesterday I increased the pressure to my normal 6.2 / 5.8 and the bike felt like it was on rails cornering and climbing felt so much more efficient. I know it's difficult to replicate these conditions on the rig but the results are a good starting point but everyone should tweak them for the terrain and conditions.
I am very wary running too low on fronts. Back slipping is bad enough but I have had near wash out of the front when i had a leak that was dropping the front pressure until it was scary in the corners. I had to stop and pump back up until home. Downhill into a hard corner on soft fronts is not fun. I think the data is interesting, but point to finding ones best balance of f actors. - Cheers
I dropped my pressures to 4.5 bar front, 5 bar rear 28mm and did a ride past Silverstone. For me, no faster but felt a lot nicer, easier. By the way. Have also been experimenting with a thin layer of talc between butyl inner tube and tyre casing to see if that reduces internally induced rolling resistance. I think it might do...
To my knowledge, Pogačar routinely rode 30mm Conti tyres on fat, tall Enve aero rims for this year's Tour win. Although his body weight is very low which makes that counter-intuitive, of course his average speed is a lot higher, plus the aero gains when he attacks off the front become far more significant with that combination.
Re: your comments about best tyre pressures on cobbles Olly, don't forget that most of Paris-Roubaix is ridden on tarmac or concrete slab, so the tyre pressures the Pros ride are necessarily a compromise between the rolling resistance on all those surfaces.
Finally, of course we all wince at the thought of 70s Pros riding 23mm tyres in the very same race, but then they rode skinny, very shallow aluminium sprint rims for tubs, and there'd have been a lot of deflection and shock absorption going on within those rims, plus much looser spoking, also the forgiving steel frames and forks of the time. But for sure, the ride would have been harsher.
Nice piece though Olly, fellow Physics nerd here!
He rode 28mm tires this year. Last year he rode 30s on the road and 32mm for tt.
What did he ride for TTs this year?@@prestachuck2867
Flexy rims and steel frames might reduce a bit of road buzz but there's absolutely no way they'd soften something as significant as Roubaix cobbles.
Pogacar's tyre pressure is not really relevant to recreational riders doing half the speed at best. It's like comparing an F1 driver's tyre choice to the cheap rubber for my 1.2 litre hatchback.
I disagree over the steel frames/forks and thin aluminium flexy rims, as well as the much looser spoking from those times. These would all, together, have had a softening effect on cobbles, although not as much as the much larger tyres used these days. I'm just making the point that you can't simply compare tyres now and then, its not that simple. The entire bike "system" was different, you take it as a whole. Modern carbon fibre bikes can be made with more flex, but for big, instant impacts steel is very absorbent. And Pogačar's tyre pressure IS relevant to me. I ride a Colnago, I ride Schwalbe Pro One Tubeless 30mm, and although I'm in my mid-60s I can still average Evens on my own, and faster in a group. I get the same big tyre benefits as him, with perhaps 0.5 bar higher pressure because I'm fatter than he is, but I get those same rolling resistance gains. He'll of course get more from them aero gains than me, because he goes a lot faster than me. Thanks. @therider4909
they also rode 13-15c rims and Tyre stood over the rims.
now 19C-21C and sindewall are very straight.
Excellent tech video. I proves what I always have believed, the more you get into bike racing, the more it turns into car racing. Silverstone, even!
Might want to change the title. I thought this was a clickbait type video with nothing useful, but I watched when I saw the runtime and I am glad I did, always love good testing.
So the title is NOT click bait, but because you thought it was they should change it?
Wouldn't that make the new "changed" title click bait to attract people who mistakenly think the original title is click bait? lol
I second this,. This was the only time the title is less promising than the content.
@@space.youtubenope because it sounds like an ad, which it is not. He’s suggesting changing to a title that doesn’t make it sound like an ad for some product
I agree, the title and the picture don't give the feeling that the video will be very interesting. And yet it is nicely done, with such a good scientific test. If it wasn't a GCN Tech video, I would not have try to watch it
@@KelvinSuddith You think the title of this video sounds like an ad? What sort of product, in your imagination at least, do you think the title of this video would be trying to introduce? It literally states what's on the tin and you people are aren't happy? lol
Some people just like complaining I guess.
Ps I don't think you understood my original comment, but thanks for trying all the same. 😁
Great video. Just to add, on Arenberg alone the system takes approximately 23000 hits (2300m x 5 cobbles/m x 2 wheels). Within those 23000, it's the random missing or proud cobles and wide gaps that are the problem.
The system doesn't take 23000 hits. You often don't hit anything for a full meter with either or both wheels. At 40k/hr you fly over a lot of those cobbles.
gcn should keep doing videos like these
Thank you, that’s what we’ll try.
Great stuff, Ollie. Well done.
Possibly the best cycle science video I have seen. Vindicates my view that a lot a cyclists inflate their tyres to high. 65 to 80 psi is a good median for most terrain.
Totally depends on weight and tire width
Plenty of bike shops have been guilty of this as well. I recall buying a few bikes, and them pumping the tyres up to over 100psi - despite me asking them not to. Got home and let the tyres down to a proper pressure.
If bike shop people were super smart, on average, let's be real, they would have had a different career. Cycling is also a world that's resistant to change.
@@pierrex3226Ouch! Spent four decades as a professional bicycle mechanic in a LBS. My customers would disagree with that sentiment.
@@stevengagnon4777 You missed the "on average."
@@stevengagnon4777 No they wouldn't. The dentist coming in to buy his pinarello or cervelo wasn't thinking you were smart. Bikes are simple as fuck too - you can build a bike from scratch in a few hours. Now, of course, perhaps the average member of the public who goes to a bike shop can't remove the back wheel so maybe he or she thinks it's an incredibly complicated mechanical device and you're a genius or something, but you'd be a fool to measure yourself against them to give yourself the impression you're highly skilled. if you spent 4 decades doing bike maintenance you wouldn't learn anything new after the first 2 or 3 weeks.
They may pump it up to that to seat the tire
I run on 28mm tire a long time. It's the sweet spot for me. Thanks for the Tech info. videos like this! Adds efficiency every time.
This rig looks ideal for comparing the performance of an old school tubular with a TLR. For example, the Pirelli P-Zero is readily available in both formats in size 700 x 28. I would expect the casing material and layup to be identical too. Of course the big difference is that the tubular will have 30% more usable casing making it much more compliant and comfortable at any given pressure not to mention almost impossible to pinch flat. Also, one would expect the tubular to handle a much wider range of pressure especially on the low end owing to the flangeless rim profile.
How is it near impossible to pinch flat a tubular? It still has an inner tube, it's just woven into the casing
@@matthiaswuest7271 A tubular rim has no flanges. Pinch flats are caused when an inner tube gets "pinched" over the flanges.
This has been tested before, frequently. Tubeless tires had a lower rolling resistance at equal comfort levels.
Tubeless will be better than the tubular. There is a reason cars don't use tubes.
Tubulars, despite their name are just constructed with a built in inner tube and that layup will have more internal friction reducing compliance at a given pressure. Tubeless tires only have the casing flex to tune.
Interesting stuff.
As a recreational road cyclist though I don't dive this deep into the setup. 5.5 to 6 bar pressure on 28mm tires is all I need to know good to semi good roads.
same for me. I typically pump it up between 5 and 6 bar. Good compromise.
When I look at other riders, many of them barely have 1 or 1.5 bars in them.
I'd like to see more about tubeless tyres and inserts and how they affect handling and puncture resistance. The drift that I get on my tyres with a foam insert is very much like the feeling I got with high-quality CX tubulars. There's a drift, but it's controllable. You don't want that on the road necessarily, but it feels good on gravel bikes. But I think there's a lot to be done there. High quality TPU tubes are nice I guess, but they're still a tube and I feel like that has very specific drawbacks that most riders and unsupported racers shouldn't have to contend with.
Fascinating and well researched test (given the constraints), very well presented by Ollie. I need to lower my tyre pressures 🙄. More of these please GCN.
In other words, on tarmac: it will depends of the type of tyre, rider weights, and pressure to get more or less 3 watts. I'll continue use my 80 psi (between 6 and 5 bar) and it will not going to affect my super 195-205w on average rides.
Actually there a different kinds of tarmac and silcas excellent calculator also account for this. But of course the calculator depends on the values you enter.
Looking at graphs showing coalition between rough/average/smooth tarmac and tire pressure shows the penalty from to high pressure is significantly higher vs the penalty riding with to low pressure.
Great content!! More of this type would be appreciated.
📝
great video...more width testing please
You’re insatiable when it comes to tyres 😀
Ollie, perhaps the most geeked out video to date for you. I couldn't stop watching it! 😂
Loved this content Dr Bridgewood.
Such a high quality video! I love that Pirelli have been putting such a massive investment into this. I absolutely love the Pirelli Gravel H tires on my gravel bike. They roll so good on gravel and surprisingly well on pavement too. It would be fun to see how they compare to other tires and at different pressures.
I don’t think the pros can go lower; the cobbles at Paris-Roubaix are totally different! This drum simulates „urban“ cobbles with a relative regular pattern - at P-R you have random stones and the wheels are hitting steps up to 5 cm and more. On that you will get pinch flats much easier
That's probably why some riders run tire inserts
Ollie, geeked out to the max! LOVE IT!!!! Ask the lab nicely if you can go do some of those other test protocols you mentioned. I. for one, will be glued to the screen!
My first mid-end road bike, long ago, had 1.25-inch (32mm) tyres, with a recommended pressure of 60 psi (4 bar). When I got some money, I switched to 20mm sew-ups running at 125 psi (8.6 bar), and the decrease in resistance and increase in speed were dramatic. Today I ride 23mm clinchers at 110 to 120 psi (7.6 to 8.3 bar). Sorry, I'm sticking with "old school", never going back to fat, soft tyres. Those are for paperboys. Yeah, I know, Tadej goes big and squishy and wins everything, but I suspect the advantage he has over me is probably down to something other than tyres.
You just feel like you are going faster due to the vibrations, time yourself 5x on higher and lower psi on long rides and get back to us. Maybe you are heavy, in which case 120 could be your optimum.
I still have a bike with 23mm tires. Vittoria on Mavic Open Pro.
Excellent video Ollie. You are the best at all of this scientific stuff.
Dylan Johnson recommends 45mm or wider tires with pressure about 15-20 psi for gravel racing.
These numbers refer to his body weight, while he also is running tubeless. If I do that on my clinchers which have to support my 95kg, I would have a flat within 10km.
Continental Racekings
How much is that?
20 psi is like flat.
@@rabidsminions2079 Is it? Sounds a lot. If it was 20 bar it'd burst
So in summary, for most of us plodding along at 25-30km/h on reasonable (but occasionally pot-holed) tarmac, tyre pressure makes precisely 2 parts of f**k all difference LOL. Besides, this test takes no account of the losses through the front tyre, nor does it consider what happens when you hit a pothole. I think I'll protect my carbon wheels by running the tyres a bit on the high side, plus I'll maintain some grip while cornering hard without the tyre rolling off the rim!
I found the table towards the end of the video great for some of us. For the rest of me, going lower than 35 km/h would be more helpful.
Thanks for making this video showing other people what I have known since I was 8 years old. Even at the ripe old age of 8, I was racing my bike against other kids in my neighborhood, and learned that keeping my tires pumped up made my bike roll faster. What exactly is the right pressure for your tires? I usually start at above the recommended pressure on the sidewall of my tire, and I ride the bike every day. As the days pass, the pressure decreases, until the tire becomes soft. You can run the pressure again, and as they days pass, you can figure out what is the optimum pressure for your tire, your weight, and your roads. On that day or days where you get the best performance, check your pressure, and pump up your tires to that level before every ride.
On finding optimal pressure, an industry professional said* to "search for smoothness". When you feell the vibrations, it's too high. But much lower than that isn't great, either.
*) It was an interview with the less mainstream and less performance oriented chanel "the path less pedaled" (home of "partypace"). I think, Ollie and another presenter have met Russ and Laura on a shoot on some mountain this year or so.
For myself, I would be wary of running too low on the front tires, as it tends to wash out the front end in hard cornering. Over all good data is good to have, and can lead to the sweet spot. Different set ups for different conditions, seems like a normal way to look it things.
Always interesting content. - Cheers
I have been riding MTBs and roadbikes since 35 years, even rode some competitions and countless alpine passes and granfondos all over Central and Southwestern Europe. Always pumped my tyres to the point they "felt fast", which may have been all wrong. I don't care, because the only point I did not enjoy a ride because of tyre pressure was when it suddenly went to zero - aka I suffered a flat. If you do not make a living by racing bicycles, there is no need to overthink this, just pump your tyres and go for a ride!
Well if you spend a lot of money on a fast and/or comfortable bike not optimizing ture pressure seem like wasting money....
Excellent report. Very helpful. My pressure has been too high at 7 bars... will test at 5 bars on next ride.
Good vid, so narrow is faster? Shame not to have had a 25mm in the mix.
Yes it is.
If your rims made for 25mm tires yes it is
I used to ride our local century on my FWD recumbent with a 24"x1.375" width Cheng-Shen commuter tire on the driving wheel. Didn't need to pump up it to 80 psi, and it was more comfortable at 60 psi. This was on average US spec tarmac with all sorts of local differences in quality, from being less than a year old to 20 year old weathered/old tractor tire washboarding and pitting.
One of your better tire pressure videos, but you should've picked a better brand for the second tire.
You actually don't. One thing about "science" is you always start with a wide a difference as possible to make sure you can actually measure something of value. If they would have gone in with a GP5000 and a superfast tire, there may not have been much to talk about or worse yet, the wrong conclusion.
I'm good with the cheap tire as a base. Though in an ideal situation they'd have tested like 10 different tires. But that could have taken days.
Hey Olli, just to make sure: When you compared results to the SILCA website you put in the "measured width" of the tire at 28mm.
While I do not have the Pirellis for comparison, my 28mm Schwalbe Pro One TLEs for example are actually 31-31.5mm wide (hookless rims). The difference in recommended pressure acc. to SILCA is a full 1 bar compared to a tire that is really only 28mm wide.
I used to run 23mm tyres on cobble at 7 bars, for my commuting through Paris and her suburbs. It's shaky, but you simply get used to it. :)
I run 28 at 6 now, and it's already a smoother and more efficient ride, even as an amateur.
As you mentioned, however, in a racing situation, it's easy to conceive how different the mindset and savings would be.
I noticed the front end was rigidly fixed with no wheel or drum. This DOES have a huge effect. Would LOVE to see the test rig with a front wheel setup.
In the days before my spinal prolapse ended my riding, I played around with this. Different width/pressure tires on the front (Keeping the back fixed) had a noticeable effect. I was running Conti 4000'''s 21/23/25.. Nowadays I potter along on my flatbar roadie and Schwalbe Mrathon at 60-70 psi, so it was interesting to see maximum comfort probably equals maximum efficiency. I think I'll go down another 10 psi. Thanks. informative video.
2bars on 28c for a Roubaix or even average hard cobblestone has one huge problem…
That the drum doesn’t recreates!
The usual Potholes and protruding cobblestone odd edges every 10m-20m.
Great content as often on theese topics !
This is brilliant.
I usually inflate to about 2.5 bar and I can feel the difference when it is too low.
Good science Dr Ollie. Enjoyed this. Can't subscribe as I'm already in but worth a thumbs up and a positive comment 🚴👍
Liking the video and leaving a comment also helps us a lot, thank you 🫶
Christ I’m running 70psi on 40mm gravel tyres!! No wonder I’m bouncing around. Great vid! And yes more tech please 😊
"96% of Cyclists Get Their Tyre Pressure Wrong. How To Get It Right"
Step 1. Build a multimillion pound rolling road facility
Step 2. Test every type of tyre at every possible pressure on every possible surface
Step 3. Let a bit of air out of your tyre
Seriously though, the video was much better than the title - good info!
Great Video! Sounds like you definitely need to go back and do all the tests you need to, all the sizes, all the pressures etc. I have no idea what this would cost you but I'm sure all the viewers including yourselves would greatly benefit from a update video with all the intel you will discover.
I don’t run the same pressure in both tires. Front is always about five psi lower than the rear.
And that should be rigth... if it the rigth pressure
That is standard advice, but without a rig testing both tyres at the same time its hard to know if its the correct policy. Seems legit due to less weight over the front, but the arms act as shock absorbers unlike the lower body effectively reducing weight on rough surfaces? So who knows for sure, maybe it should be 10psi lower?
@@benedictearlson9044 In addition to the rear weight bias, my theory goes like this: 1) A softer front tire is more comfortable and reduces numbness on long rides. 2) I’m less likely to get a pinch flat on the front because I can more precisely absorb or avoid hard bumps, and 3) I can avoid road hazards such as glass better with the front tire compared to a back tire.
Running lower pressure in the front tire is for comfort and traction. Every thing is a trade off, if you want the least resistance High pressure and the smallest contact patch are the your friends, if you want a less fatigued rider, that five PSI lower is nice. Every ones riding style is different some crazy people can handle rattling their brains and a few of these riders may even have uncanny bike handling ability, these are the ones that seem to walk away from other riders when the going gets rough. A more aggressive tread pattern on the front, if necessary rear too, coupled with a narrow width, has less resistance than an under inflated wider tires. Question is are you the type of animal that can take all that punishment? For one race fine, for the season???
yeah...i feels the same with your point 1
Thanks GCN for one of the most interesting videos I've seen about tyre pressures !
When GCN applies Peer Pressure: "96% of Cyclists Get High Blood Pressure when they get Their Tyre Pressure Wrong . . ."
Slow Leaks: 😉
Local Priesthood Cycling Club: "Pray Sure!"
Definitely true for the time I used a pressure gauge in addition to that on my floor pump. Re-adjustment of pressure took time, effort and ruined my mood. When the gauge was not working properly at one time, I smashed it on the ground, completely destroying it. I never replaced it and using just the gauge on my pump leaves me a much happier cyclist now.
Pssst... Wanna tip on comfort?
@@whazzat8015 "Psst"
Fascinating subject. Extremely well presented. Thanks Ollie. I'm off now to let a bit of air out...
id love to see a calculator that we can enter our weight, tire width and riding type and then just get the right pressure to add
the silca one does that
This is fantastic stuff! The competitive cycling world is at a ridiculously high technical level these days. For all the miles of pro cycling I watched this summer it kept me interested. The advanced tech in cycling did that! However on my bike a universe away it’s a enjoyable physical pastime.
It seems like you want the pressure low enough and tire size large enough to absorb the average road bump size, say 1 cm, plus a little firmness for the big bumps without bottoming out.
And if the road is only bumpy for a portion of the ride and smooth for the rest, then you want to increase pressure a bit to balance out the efficiency of high pressure on a smooth surface.
The trick is to find that balance point, approximately.
Fantastic study. Thank you. GCN Tech for useful data and product evaluations
Or go to 18:06 and pause if you're in a hurry. I think I'll try 80 psi (5-10 psi lower) on my next ride and see how it feels. No mention of whether tire pressure should vary front to rear. Early 80's it was 105 psi with 20 width. Times have changed!
Just use a tire pressure calculator
awesome video as usual, kudos.
In regards to the wider tire, if you’re putting a wide tire on a rim that’s designed for a narrow tire when we talk about optimal fitment of course it’s going to be slower. It would’ve been interesting to fit a wider tire on a wider rim that is optimized for that tire size.
I use bicycle everyday for my transport, and a lower tire pressure made the bike easier to roll and controled. I don't feel any bouncing feeling on the tires.
The big thing with the Silva calculator is that you use ride weight and the weight of the bike, including filled water bottles! Its great.
Science Viewers, at 4:50, when Ollie says "One Hertz a Second":
😮
Excuse me while I withdraw money at the "ATM Machine".
Oh dear, poor from Dr Bridgewood.
It gets faster and faster! First it's one Hertz, a second later it's two Hertz, then three Hertz. Soon you can hear it. Ride long enough and you can see it it.
One hertz a second, how many BPM per minute is that?
/ss
Don't be too harsh, he's a chemist!
Don’t forget that the front wheel is seeing pretty close to the same loads etc. So a set of nice tires!
Were the testers including the “load” of the front in their watt calculations.
Love this nerdy content; please keep it going if you can!
I'm currently running 32mm tires with TPU tubes on my road bike. According to the Silca calculator, I should be running my tires at 4.5 Bar (65psi) on paved surfaces. That's actually very squishy in my opinion. Instead, I run 5.5 Bar (80psi), which seems to be ideal: comfortable, smooth, but it doesn't feel like I'm riding through thick sand.
OK, I don't actually run 80psi all the time. Most of the time, I'm not even sure what my tire pressure actually is. When I inflate my tires, I go up to 90 psi, sometimes even up to the recommended max of 100, and then don't mess with them for 2 weeks or more. The tires lose a couple of psi a day. For the first couple of days, they're honestly way too hard, sort of bouncy, which isn't good, but then they feel fine, and when they finally start to feel too squishy, which is at about 70 psi for me, I start over.
Same here! It creates some variety in the rides haha
Bad practice. Should just inflate tires before every ride. Just aim for between 60-80 or pumped before every ride.
Tubeless tires lose a lot of pressure every day, very unpredictable
@@the_kingd0m "Bad Practice. Should..." Cycling is like a church.
@@the_kingd0m If I wanted to inflate my tires before every single ride, I would just use latex tubes.
This was fascinating. Keep heading back! It'll be like Alex Dowsett testing everything he owns in the wind tunnel which was full of surprises (and even generated a product for Nopinz)
28 GP5000s at 80 psi for me.
Great video. Wish you could have explained why the higher pressure was less efficient on the asphalt.
Now I need to throw a spanner in the works. What about hookless rims/tubeless which have a psi max of 72 (contin 5000)
My hookless rims have a max pressure of 45 for my 35mm summer gravel tyres and a max of 40 for my winter 42s, honestly I can't tell the difference but I've not done any personal testing, I usually run 5 psi under at the rear and 3-5 less at the front and it's all been hunkydory, might drop it a bit and see if there is any discernable difference 🤷
Gravel tyres seem to avoid the problem that road rims are having. My road bike has 28mm and there seems some concern with tyre blow outs due to narrow rims. Haven’t had an issue yet but lots of stories of issues. Argghhh
@@stevesimpson6021 I think also the higher pressure needed for a narrower tyre also plays a massive part in this...go wide, go low and you'll be fine😉
Great video and some really interesting comments. Will be adjusting front and back pressures before my next ride. Thanks so much.
dylan johnson was right mountain bike tires for cobble road races
Paul Sherwin used to say the same. If you're coming to Roubaix to ride the cobbles, bring a mountain bike!
he's not right.
Intriguing to see how much the chain and derailleur bounced around on the simulated cobbles. That definitely reduces the efficiency of the drive train!
Ollie asked how they managed Paris-Roubaix on 23mm tires back in the day. Well, they had much more forgiving steel frames and forks, and 28mm tubulars on light aluminum rims that were 10x as forgiving as wide and deep carbon aero wheels.
In the steel-frame era they rode on 20- to 22-mm tubulars pumped to the maximum allowed pressure. Indeed the flat box-section alloy rims factored in, it's only a few years ago that pro teams put these on bikes especially for Paris-Roubaix when they would usually ride deep-section carbon wheels for everything else.
Many used Paves for the Roubaix...I used Paves all the time . Switched to 26 mm to 28 mm tubulars in the early nineties...I was heavy so it made everything better.
Well, I think they had way more punctures, too. It was routine for riders to have multiple punctures and still win, which is pretty rare today. (My recollection is that when Hinault won in 1981 he had 4 punctures and 2 crashes, or vice-versa.)
@@rkentwenger5095not nescesary, riding on cobbles is more technique than you think, arenberg is an exception, but every cobbles pave has a ridge, ther where you would preferably ride. And every section has his own few golden speeds. On this speeds you fly from one ridge to the other. A little faster you jump more, a little slower the same. You see it even in action when Alex was riding 35 km /h he was in discomfort.
When he slowed just a little the vibration was smaller. At even slower speeds, he vibrated more,…..
High tire pressure gives puncture resistance, it is total system, material choices matter
@@einundsiebenziger5488 as you mentioned the flat box section rims ( that I still use) made a big difference. They were relatively strong ( stronger and much lighter than clincher s) and could be easily tuned with spoke count, rim weight. spoke guage and tension. Being flat and wide they had good vertical compliance and good lateral stiffness. They really are a joy to ride and thanks to the acceptance of and availability of wider tires in tubulars , even better. I always rode paves anyway but the newer tires certainly give superior puncture protection. Those tubulars were also made from cotton which also softened the ride and for that special day with absolutely no rain in the forecast there was silk . Even at 100 kilos I could ride a 330 gram rim with 32 skinny double butted spokes will alloy nipples and a decent 23 mm training tubular up front ( being dishless made it possible) and as long as I didn't hit an immovable object they were plenty strong for daily use. Once I discovered Paves and those wider rims I never went back . The ride and confidence in the twisties was awesome.
I'd love to see you modify pressure on the fly via a KAPS system. Great video Ollie!
this is the content I live for.
One of the most informative and educational videos from GCN Tech. Learning a lot from these kind of videos. 👌
conti GP 5000 23/25c a regular clincher at 7.5/8 bar, front/back on a good asphalt.
Very interesting. This is the best drum testing I've seen and probably the closest to roll-down tests (e.g., Jan Heine's stuff). The whole-system approach is much more important than simple small drum testing of just a wheel, for example it is likely that most of the power lost on rough surfaces is dissipated as heat in the riders body. I look forward to many more results from this kit!
I know everyone likes to think there is a chart they can refer to and not think about it any more, but jeeeeez. There is one easy way to get the right pressure for a road bike -- on the day of your ride, ride a bit on the route you are taking, starting with obviously too much pressure, and slowly reduce the pressure until just the road buzz goes away. It accounts for everything -- your bike, your body, your tires and tubes, the road, the weather, etc. If your route has wildly varying surfaces, either adjust as the terrain changes, or decide which section you want to accommodate.
Back when I was younger, as soon as I could afford it I got a full-suspension mountain bike with rear and front suspension that were good enough to handle jumps beyond what I myself felt safe performing, and always kept the tires at the maximum pressure allowed to reduce the odds of sharper bumps or hard landings pinching the tires and hitting the rims, to maximize the life of the rims and reduce the risk of cutting into the tires with the the rims, leaving the suspension to take care of making it a smooth ride (it was always a bit of a tense moment pumping the tire to the limit if I didn't had my mind elsewhere and instead remembered there was a chance the tire might happen to not handle the pressure anymore and would explode this time; never had an explosion though, but I always bought reasonable quality tires, so it wasn't worse case scenario)... I have no idea whether that was the best thing to do, but it's what I did.
Tyre pressure is easy - just get your thumb calibrated.
My dad calibrated mine when I was about 10 and it’s been accurate ever since.
Interesting results. I would love to see more testing to understand the road surface, pressure and tyre width combination better. And I would love to see actual gravel testing instead of cobbles but that cannot be done on a drum.
Has anyone noticed their bike has sketchy steerting under 90 psi on 25s with tubes? Tried it once, wasnt confidence inspiring in turns.
Such useful information, thankyou.
Not gonna lie, those reflective stripes on the cheap Amazon tyres actually looks pretty cool and is a pretty innovative way to add some retro-reflectivity to your bike at night.
It’s not innovative Vittoria and Shwalbe do this for a looong time in my experience.
I wish Continental would add reflective stripes to their GP5000 line.
They have reflective strips on a GP5000 AS tyres.
The relflecive strips are a big difference for motor vehicle drivers at night. Would like to see them on most tires.
@@SebastianTominecit's definitely an underrated tire. The small loss in rolling resistance is well made up in real world riding...especially in the wet and cold weather of both spring and fall. It doesn't necessarily have to be wet as they will give better grip on dry and cold roads too. I would like to see more tires with actual treads too ... I don't believe that slick tires are good for all around real world riding. Especially since the acceptance of the wider tire.
Remember a bike has 2 wheels and although the front wheel losses are likely to be different from the rear wheel losses, as an example, times the losses/gains by 2 and the magnitude of the effect becomes even more significant.
Always amazed me in kids triathlons, which bike events are often run over very bumpy grass and parents who were road riders, would have their kids tyres pumped up super hard, poor kids!
Couple of things. First one, if pressures are this important, what is the most accurate and CONSISTENT way we should measure our pressures as normal riders at home? What's the go-to gauge for measuring? I'm going to guess if I took 3 different floor pumps, couple of mini pumps, my air compressor, etc, they'd all read differently.
Second one, pros are drilling cobbles at way faster than 35k/h, their pressures are different than us noodling around. Plus some of those classics riders are heavier (most are).
Thirdly - Dylan Johnson has been saying for years pros should be on 40-50mm wide tires for the cobbles, no one will do it, but after seeing this data, it's something to consider (different bike frame of course).
What your saying makes obvious sense i would have thought..
My floor pump over states the actual pressure by 18psi.
I didn’t know until I bought a digital pressure gauge.
For the third point, maybe for cobbles that is the best option but most races with cobbles have significant amounts of smoother surfaces so mid 30s is probably the right way to go for them. I agree with your first point though, normal people just have to go off a track pump or something and kind of see if it feels the right pressure.
@@_Tp___exactly what I was thinking. tire choice has to consider the tarmac and cobbles. If you just take a 50mm tire to monster truck over the cobbles, then yeah it will be faster but on the tarmac the rider would suffer and be much slower than the group riding 32’s or 30’s
GCN made that video, a mountain bike, with mtb tires, is faster across the cobble sector. The thing is Paris Roubaix is a race mostly on regular roads.
I would love to see this exercise with tubeless gravel and wider slick tires with and without air liner inserts.
How about running the tyres hard enough so they don’t make a noise and soft so they don’t buzz on the surface you are riding on.
You’re right, Intuition isn’t a bad thing ma man.. sometimes science and analytics is only justification for a job..
Really interesting video and some good takeaway points to consider.
What a joy to wake up and geek out on some bike research...can't believe we get this content for free!!!
🗣Tickets please 👮♀
Videos like this really get me excited! I’d love the chance to visit test facilities like this myself (especially alongside Ollie). If slightly heated tires offer performance benefits, do you think we might see 'tire warming' technologies in the future, allowing riders to start with optimal tire temperatures from the get-go?
25c Tyres, Butyl Tubes, 7 Bar / 100 Psi.
Road Only, No Issues, Rapid 🤙🤙
Going on longer rides, say over 50 miles and beyond, I really enjoy the 30mm hook less tubeless tires (70 psi) it saves on the sit bones and hands from the pristine asphalt we have here in Minnesota. The lower pressures I can run and not worry about pinch flats are worth it. I had 25mm tubeless that were at 100 psi and it would shake your teeth out.
This is what the majority of pro's are now riding, just 28mm, hookless tubeless. Maybe higher end rims and tires than you perhaps, but if you look it up this is now pretty much the norm. Completely different than just a few years ago.
The weekend videos are just videos making sure the channel sponsors get a shout out.