Max. What slows me down really are the snake bites. Everybody should try riding a flat sheet of ice. No vibration, very little rolling resistance, astonishing speed.
Thanks for the great video! I have tested, tested and tested.. And for me the fastest combination is 23mm 110 psi front 120 psi rear?? But the problem is that you no longer want to find tires and rims that can withstand that much pressure?!
Not only is the information well presented to both the technically informed and layman alike but the I just have to add the videography is absolutely amazing in this video! These amazing shots/angles/speeds we just can’t ignore how much effort it must have taken to produce this masterpiece. Well done GCN.
As a 50-something who's been road cycling since the 80s, I ran 20 or 21mm at 115-120psi for decades. Went to 25mm in 2018 but still put over 100psi in them. I'm down to around 80psi now, so I'm slowly adjusting to what the science says, but it's a slow process. I probably need new rims before trying 28mm - mine are from 2009 and came shod with 23mm tyres.
I feel my rear bottom out at 80psi, tyres rated for 110 I used the calculator and my weight shouldn’t really be bottoming it out I also just like the feeling of 100-105 PSI
Where I live, the roads are terrible, but I have a bike that is capable of running 32mm tires, and it has changed my life. Running high volume at lower pressure has made riding much more comfortable, and I honestly don't feel any loss rolling resistance. Coming from a background of racing in the '80s to the '90s when skinny and hard tires were the norm, this is a great change! I'm happy that cycling is letting science take the lead over tradition.
I've been on tire pressure journey for about 1.5 years now - down from 120 to 80. So much more comfortable! This is best video on tire pressure I've seen yet - they key takeaway for me is to use the calculator to get into the right range, and then don't stress about it - you've shown that 5-10 lbs either way doesn't make that much difference. Take the Comfort...And don't forget - Resistance is Butyl!
I like higher pressures, still, after half a century of riding, but even in the heyday of skinny (18c) tires, 120psi was too hard. Mind you, I base that on cross-country treks mostly asphalt, but some gravel/crushed limestone (what's termed 'gravel' is slightly different UK to North Am, I'm a Cdn/Brit Dual). I found 100psi on the early Specialized 18c was at the top end of efficiency, sanity and durability (this was before polyaramid was used for puncture resistance) but even as I've increased tire size dramatically over the years (I'm using 4 Seasons 25c front, 32 rear), the front will be 28c next replacement) I bought into the 'lower is better' spiel, only to inch back up in pressure to a 'feel' of optimal at about 70-80psi. Something today's generation fail to include in the 'feel' of what is right is the frame behaviour. I ride a classic 531 frame which is very lively and comfortable. (I had the chain stays dimpled by a framebuilder to accept the 32c width) one of the best mods I've had done over the years.
Needless to say, I ride hooked and see absolutely no reason to want otherwise. Built up my last wheels a decade ago, they're still in superb shape. (Mavic A319s). Engine still going exceptionally well @74yrs.
Si, as a nearly 60 yr old roadie, I’ve always used relatively narrow rubber 25-28mm at higher pressures. However, I’ve recently bought a Giant Revolt running hookless rims and CADEX AR tyres at 40 psi and the difference on ‘normal’ (i.e. potholed) roads is incredible - everything is better, speed, comfort, grip, and not one puncture all winter….I was very sceptical before changing, but wouldn’t go back to ‘narrow’ high pressure rubber now. If you’re a racer, I get that you still want narrow tyres at high pressure, but for most of us hobby cyclists who want to ride for fitness and enjoyment, low pressure tubeless would seem much better on rubbish UK roads. Love the videos, keep them up! Rich
I've been running 28c Conti GP5K at 70 psi. I use latex tubes which lose air slowly so I pump up and check pressure before every ride. Sounds tedious but it's my ritual and the added benefit of meticulous awareness of tire pressure is that there are no surprises when cornering fast downhill.
I don’t get how people can go for a ride without checking their air pressure, except on my daily bike (very short and slow ride). I totally agree with you, it’s a matter of security.
"Cumulative fatigue reduction on longer rides" is another important benefit. This was mentioned in another post and it makes so much sense I ordered a set of 32s just now. The marginal gains on short rides is nice, but the benefits for 100 or 162K rides should be much more significant!!!
I weigh 57 kg, and normally ride fondo or century on weekend. I run 32c at 50 psi, I tried 55 psi but the road chatter is atrocious. The road surface where I live left a lot to be desired. I tried Silca tire calculator and actually it suggets 52 psi.
@@gcn Since I still have nearly new 28s, I would consider mounting them for a short TT on smooth roads, but the gains only barely outweigh the trouble.
@@jojoanggono3229 if you weigh 57kg why on earth are you running tyres that are nearly .5kg heavier. A 32 mm tyre is way to stiff and heavy for your weight. You could get the same comfort out of a 23 or 25 as the benefits of fat tyres diminish greatly the lighter you are.
@@gcn i switched to 32c from 28c due to the fact that most races I attend to are flat crits or flat 20 km rounds with multiple laps with many, many fast corners and wider tire with lower pressure gives me much more grip and confidence in cornering at a really steep angle. I never felt slower because of this tire choice, actually I'm riding faster cause the roads here are far from perfect and pristine.
Good video Simon, you got the theory about hysteresis vs vibration attenuation well dialled and explained it well. I've got a video series in production about the issue too. However for aero protocol, i couldn't get the hookless Zipp up to my control pressure due to the 5 bar limit. On my medium textured asphalt, a fixed-CdA test with pressure sweep showed 76psi to be fastest on my control tyre. Simple as that. For heavier riders on smooth roads, who don't want the aero and weight increase of tyre upsizing, hookless just isn't viable. And lets be honest, hookless is being pushed because its MUCH cheaper to mould and de-mould.
76 is actually quite low for your size. I don't remember your weight but you're like 195. It makes me think that I should drop my pressures a few psi more.
.. and hookless rims are supposedly not as structurally strong as hooked ones, although I guess that they are passing the UCI and other required testing. Would be great if you could comment on that.
I’ve done some Chung analysis testing myself.. and yes, on smoother pavement the optimal pressure does go up. BUT, since on smoother pavement the optimal pressure curve is flattened.. I got 20psi around the “optimal” pressure where the power differed by .5 Watts most of that span on the lower pressure side. So from a PRACTICAL point of view I’d take the .5W hit for better, traction, VASTLY better performance on any rougher patches might encounter, comfort , vibration related fatigue etc.. those 15psi don’t actually get u that much at the end of the day except in the case of a straight out and back TT on smooth pavement
@@Membrillo81 different tyre technologies have different side wall stiffnesses. For a 23 clincher 1psi per kg was the general rule. For a hookless it’s about 0.7 per kg. The hookless tyre is much thicker to maintain its shape.
I mostly pick my pressure based on absolutely minimizing flats, not performance. still riding 80-90psi on 28s at ~175lbs. (some of my bikes still don't have tubeless)
I had to ride home with a lower pressure after a roadside repair the other weekend mainly because my emergency portable pump is crap! I was expecting to be slowed down by it a lot however on our rough county lanes it didn’t actually make as much difference as I expected and was a bit more comfortable! I am going to experiment with slightly lower pressure from now on.
In automotive industry we use coastdowns to measure frictional loses. Do it both directions to deal with wind effects. Similar to wahoo spin calibration but on the road.
I have tried lower pressure and there are other considerations as to why to use higher pressure for road ( in particular) and gravel. 1. I got far more punctures on lower pressure (tubes). 2. On lower pressures I didn’t like the feel of the back tyre which I was always checking to see if punctured. 3. The difference on performance are marginal and can be different from these controlled tests. 4. On road, thinner tyres are better to avoid punctures than wider (smaller contact point to get the puncture - along with higher pressure to reduce the contact point).
I ride 40 km 6/7 I did this for 4 years with 25mm tyres and punctured 0-5 times a week, i'd say on avg 1 flat every 2 weeks Last year i rode 28mm and only had 3 flats :) The 28mm tyre only went flat because of wearing down, I had to change the 28mm tyres 3 times in 1 year On avg the 25mm tyres in those 4 years had to be replaced every 2 months. This might be just me but i'd never go back to thinner tyres, they wear down alot faster and are very very easily punctured if you use tubes Do note though, riding every day through every kind of weather no matter what. so my experience might be alot different than someone riding 1-2 times a week in good conditions
After watching GCN videos during C19, I went tubeless and wide (32 mm GP5000), and used the online calculator setting up my new road bike last summer. The speed, feel and comfort of this is absolutely magnificent, It is also less problematic with short gravel sections with the road bike.
I've been following the suggestions of the SRAM pressure calculator for several years. Speed isn't my top priority, but the increased comfort on long rides is well worth it.
Only been riding 3 years, but as my bike (also of 3 years) came with 28mm tyres on 22mm rims, it seems I was reasonably lucky. Been running at max pressure (8Bar) as a heavy rider (80-96Kg) but just followed this advice, with 4.4Bar in the front and 4.7Bar in the rear and TBH I’m not even bothered about the speed, the comfort difference is incredible.
Fundamentally I agree with what you suggesting Si. Lower pressures are more comfortable and in most cases faster, esp. on ‘bumpy’ UK roads… but I would add 3 points to consider: 1. TPI rating of a tyre. Lower TPI tyres (120 or lower) with heavy duty butyl tube will ‘vibrate’ much more than a 330TPI tyre with latex tube at the same pressure, hence be slower… 2. Tyre pressure for training vs. racing. I add around 10psi to my race tyres purely for puncture protection. Too many times I suffered an unavoidable flat in a peloton, simply because you can’t see far enough in front to avoid it, unlike in training. 3. And finally, how ‘low you dare to go’ with tyre pressures, is dictated by how much you love/care about your rims. If you run expensive carbon clinchers like myself, then you’ll think twice running them too low. Once I wrecked both, front & rear rims in one go by hitting a nasty & deep pothole on a group spin. There’s a reason why Pro cyclo-cross riders are still running tubulars with the super-low pressures required to be competitive. Tubeless wouldn’t hold that pressure over that kind of bumpy terrain
thanks for the excellent tips. I don't race but can really appreciate them. My next tyres are going to be the Continental Ultra Sport III which are 180TPI, still doubtful whether to use latex or a TPU inner tube, but most probably latex
@@mindstalk Higher tyre pressure will avoid “snake bite” when running an inner tube. It’s when you puncture the inner tube in 2 places by full decompression of the tyre in one spot and contact with the rim. There’s a reason why ‘back in the day’ guys were running 120psi in 23cc tyres on narrow rims… to avoid snake bite punctures… With modern wide rims and tyres, it doesn’t happen as much, but it’s important to match the tyre size to rim width to avoid the “lightbulb” shape that increases the snakebite chance. As a bonus it will be more aero at the same time (tyre width that’s flush with the rim).
Tremendous video. I’ve been giving this a lot of thought lately. I now realize that for years, I’ve been over inflating my tires. I used to run 80 psi irrespective of conditions. When the weather improves and I can move from the trainer to the road, I’m going to dial it down to 60 psi and see how that goes.
I used to run 25mm tires but tried 28mm and ended up loving them. They're just more comfortable and smooth and at least give me the feeling that I'm going faster, but who cares when it just feels better. So, I've swapped all my tires to 28mm even if the rim is aerodynamically optimized for 25mm or the tire is heavier. That extra comfort just makes the ride much better. It's easier to dial in all my bikes to feel similar even though they are different brands since I have more volume to play with. Running them at 60-70psi seems to be my sweet spot, when I used to pump my 23mm up to 110psi. After riding gravel I've become more aware of tire pressure on the road and it makes a big difference in ride quality.
WOW! I tried SRAM's calculator and it recommends 59psi & 63 psi (front / rear for reinforced) That's below or at the minimum pressure for Bontrager AW3. I ride at 80 psi or 5.5 bar to avoid any issues of the tire rolling on a turn. If I'm on my roller trainer, I max it out.
Calculator suggests I should run 73psi (im sub 60kg on 23m tyres). I run 120 normally (mainly so I can go many days until its around 90psi). Last time I went out with 70ish psi on 25mm tyres I had a double puncture (pothole, same road as ever). Not tubeless, but needless I will continue to run 100+ on 23 or 25 tyres.... im not racing, im not chancing punctures. And neither am I switching everything over to tubeless and its hassles. Tubes have had very little issue over the decades, im not changing.
Both the SRAM and Silca calculators suggest I lower my pressure by 5 PSI front and rear, down to 85/90 from 90/95. I recently went down from 95/100 and noticed a different in comfort, but not speed. I'll try this new PSI and perhaps a pair of Si's Fearless Fly glasses and see if that works!
I wonder about the negative power loss if any, while sprinting out of saddle on low pressures. Kind like how suspension absorbes power vs locking suspension out for better power transfer.
Worth noting that the weight you put into the tyre pressure calculator should be your "system weight" which is the weight of the rider + kit + bike + any other items you might be carrying (bottles, tools, spares, etc.).
@@jefferycampbell2243 yes, so you’ll need to include the weight of anything extra you’re carrying on the bike part or your weight part. Often I’ve got a pannier bag with work stuff with me
I run pretty close to the Sram calculator value at 30 psi on 40c tubeless tires on my monster cross bike, they list ~36. Works well on and off pavement. I've had other road cyclists let me know I had a tire going flat as they passed me.
You mentioned something at 17:35 that is the key to wider tires. If you don't have the "newer" type wheels with wide rims, your cornering at lower pressures will feel horrible with 28mm tires. Streight line riding will feel fine with old school wheels and low pressures and wide tires, but you'll have to slow down in turns. It will be like going through a turn at high speed with a front tire going soft with a slow puncture.
The jump from 25 to 28s is something you notice for cushioning effect.. Prob just new rubber against tired old worn out tyres is also something to watch out for , state of the casings etc.. type of tyres treaded trainers against smoother Summer jobs . Big differences all around before you even get on to pressures.
For weekend warriors going as low as possible is worth a try. The difference in comfort is way more beneficial than the small loss in speed in my own experience. I ride 28’s between 40 and 50 psi at 85kg’s and I love it.
@@PaintrainX have you ever heard of mtb? we run wayy lower preassures even in the days before tubeless we did and we rude terrain with sharp rocks and stuff.
@@SimonBauer7 MTB tyres are totally different. They've got a lot bigger diameter and a thicker surface with rough profile. Same goes for cyclecross btw, so that was not a good point from Si. Road tyres are much more fragile. With lower pressure you run a big risk of objects wedging in or even the tyre pushing through on the rim on a bump.
Well done Simon! I really enjoyed this one. I started on the lower pressure about a year ago and have had quite a few arguments about it with others. I think this video says it all.
Thanks Si - GCN’s ‘in-depth’ videos always get me thinking especially as I still consider myself a newbie. The SRAM and Silca guides (Silca prompted by another comment) agree on my front tyre. SRAM suggests 2.7 psi more on my rear tyre. The difference seems marginal. I’m not expert so I think I’ll go with the SRAM guide.
I think there is an issue with highspeed cornering stability, pinch flats when using tubes, and tyre pressure. Personally I am around where Si said he was 50-60PSI on calculators with 28mm tyres, reality is I run more like 70-80PSI to stop some of the previous issues, the tyres just feel less reassuring when getting down below 60PSI, though admittedly they do dampen more vibrations.
I find you get more grip including cornering with lower pressures (like when I race cyclo cross). If its wet out, as a rule I'll lower pressure by 3-5psi.
Is the opening green-screened or filmed in front of a backdrop? Maybe first 20 secs? Also the bit at 1:05. The background and lighting on the bike look different.
used that SRAM gauge when I flipped to tubeless and I can definitely tell the difference. As an old timer that ran pressures of 120 to 130, running 28's at 58 lbs screws with my brain, but, I enjoy long rides a lot more now.
@@justsomedude7556 the minimum recommended pressures on my tlrs is 65 psi. I have to run mine with tubes at 95psi as the max tubeless pressure isn’t enough to make the sidewall stif enough at 80psi tubeless or me.
@@tobycolin6271 You must have a very narrow rim width and smaller width tires. I can see running 25's in higher pressures. The Pirelli's have a very stiff sidewall and even on the rims with a narrower width I have, I generally run in the upper 60's. I will edit to say, the wheels I run at 58 have an internal width of 25, So running a 32mm tire on it, you can ride lower pressures. The wheels I used today, I ran at 58\62 due to rain in the forecast, with a 23 internal width and a 30mm tire, but I typically run 62\66
@@justsomedude7556 you didn’t say you were running 32mm tyres. The 28s squirm all over the place on normal 19mm width rims. Another example of the industry creating new tyre wheel combinations to sell more products.
Great video! I've found tubeless tyres with a bit more with to completely change my experience on the bike. Much more confidence braking and cornering, but also MUCH more comfort. I think a lot of people would initially have the impression that it feels slower - but this is mostly just due to the road vibrations being absorbed so you have less perception of speed. I'm running around 65psi which is pretty close to where the SRAM calculator recommends and it gives a good balance between comfort and feel. Speeds on the bike are higher if anything.
Much better explanation of vibrational losses this time than previous videos. Essentially IT TAKES ENERGY TO VIBRATE YOUR BODY.. that energy has to come from somewhere.. any vibrations that make it past the tire, into the bike and into your body, that you feel is energy being taken away from the bike’s momentum rolling forward.. that’s where it comes from.. then eventually dissipated as heat into environment and lost. For so long ppl have worried only about the attenuation of energy at the tire.. BUT not noticed that giant, energy attenuating meat bag sitting ON the bike.. a human body has a TON of hysteresis!
I run Continental gatorskins in a 33mm with no more than 50psi. Partly for comfort, but mostly because I'm 95 kilos and like my wheels to last as long as possible until I get to my target weight. The silca Calc was nearly spot on for road conditions.
Great tutorial! Thank you for sharing.e I have recently been gifted a Synapse disc alloy bike, and was wondering about tire width and pressure. This is a very informative tutorial with pointers to the excellent web tool to calculate pressure according to weight. I am considering 32s if they fit. My current bike - an excellent Scott, again alloy with carbon forks - came with 23s and, as I had been using mountain bikes pretty much all my adult life, I found it absolutely excruciating. Living in Scotland, where the motorways are little better than bridleways, you really need to be looking at gravel tires, which is why I'm considering 32s. I'm not so fussed about speed, and was glad to hear you mention the word 'comfort' - defo my priority!
I've had these rims Zipp 303 firecrests for almost a year. I hover around 190 lbs and run about 50psi in a 32mm Michelin tire. Was a weird transition for sure coming from regular tubed alloy rims which were 90-100 psi with 28mm tires. Really happy with the upgrade, definitely way faster and more enjoyable ride.
My old litespeed will only clear 25s and I got down to 215 lbs last summer. Preventing pinch flats is my number one goal 🤠. If the new bike fairy pops by I'll consider this info (dear new bike fairy, really prefer the campy control levers for shifting. Thanks. )
Yes, everyone on here just assumes that you either have, or can run the stupid W-I-D-E rims and tires on an older frame, and not have to worry about those pesky pinch flats (and excessive 'squirm') from running 25s on an 18mm external width rim (like the Mavic Cosmic Elite rim brake ones I use), at pressures you could easily inflate them to by using your lungs, while weighing more than most big road (or even track) sprinters.
I'm still running at 100psi 25mm tires w. latex tubes. Bet it will trigger many xP . . . . But I also ride in an area w/ super smooth brand new Californian roads.
What a great video! I've been riding my touring bikes with pressures of 75 psi since the tires are rated from 50 - 85 psi. After doing a one week, 1,350 km adventure I lost sensation in my pinky fingers. The SRAM calculator stated my optimal tire pressure is 40 psi. I think I'll likely run 50 - 55 psi to observe the tire rating. That should improve comfort AND speed. Love it! Now, if I can stay away from the punctures from the wires in shredded transport truck tires. Thanks for the video!
Great video, turns out I was running way higher pressure than I needed to! One kind request: could you please at least display the measures also in bar, kg, meters and so on? I had to run a converter every time. It is an international channel, most of nations use metric. Thanks!
I started experimenting instead of just fully inflating my tires back in 2015, and it was surprised by the results. On 25 mm tires, I found that the less air I had in my tires, the faster I would be able to go. My lower limit was actually determined by tire wear, rather than impact flats or speed. I found that if I didn't have enough air in the tires, I would start putting wear on the sidewalls of my front tire, because I would tend to take corners fairly hard (I rather enjoy doing that), so that's what determined my minimum pressure, which is what I run now. I put about 80 psi in those tires. For reference, I and my bike together are about 180 lbs. I run folding Gatorskins with inner tubes.
OMG！I always push to the limit (which is 100psi), never heard of best tire pressure. After seeing this video, I went to the sram website and it suggested 66 front and 71 back. I'll definitely try this! Nice video!
I use Enve 5.6 with later and GP5000 25Mm that actually measure 27 when inflated. For air, I use silca calculator and set front to 75PSI and rear to 80psi.
I've progressively been dropping my road tyre pressures. This is partly because I've lost weight, but also partly, I've been measuring them more. I used to run about 90psi front rear, and now, I'm down to about 55 - 60 front/rear with 28mm tyres (tubes). I suspect, as Si alludes to, people are running way too high a tyre pressure.
I went tubeless on my road bike a couple of years ago and have been experimenting with tyre pressures a lot. Going on feel rather than measurements. I'm 80kg, 28mm Schwalbe Pro One tyres on hooked Hunt rims. My experiments have ended with 70psi back, 65psi front. Impressively I've just tried that SRAM calc and that's the pressure it recommends! Nice comfy ride, tons of grip, good rolling resistance. By far and away the biggest difference however has been going tubeless. Such a difference in ride/grip/confidence. And I've not had a single flat in 2 years.
Interesting comment about tubes and clincher tyres. I run 26mm tyres on 21mm internal rims (S-Works Turbo cottons, Alpinist CLX). I weigh 73kg and my bike is 6.65kg. I use latex tubes and run front 65psi and rear 70psi and have experienced not a single pinch flat or normal puncture over 12,000km on UK roads. I think there is a misconception that clincher and tubes pinch flat at lower pressures, that may be true at cyclocross pressure, but I have not found it to be case at typical tubeless road pressures. I think tubeless tech has a place, but I found it such a faff having to check sealant levels and roadside repairs are just plain hard with tight tubeless tyres. Good clinchers and latex tubes roll faster and weigh less as well.
I run a similar setup as you describe. Pinch flats do still happen if you hit a REALLY big hole in the road. I've only had 2 pinch flats in the past 80,000kms or so, and both were severe impacts.
Agree. Bought some 25mm Conti 5000 tubeless, and couldn't even mount them on my Cosmic Carbone 40 rims. I must have wrestled with them for a couple of hours, trying all the tips to get them on, a bit of lube, leaving the tires in the sun, heating them with a hair dryer, a handful of levers, and finally gave up before I started hurling things about the room. Give me some lightweight tubes and regular clinchers any day. I've run tubes and clinchers for years and only had 2 pinch flats in the last decade or so on the rough Canadian roads in about 80k kms.. Both from hard hits to a good pothole. I weigh 80 kg, bike is 8 kg and I usually run about 85 in the front and 90 in the rear.
I'm a bicycle commuter, and ride a lot in the dark in the rain, which does a good job concealing potholes, sunken water valve covers, and big cracks in the street. I've had several pinch flats, running over 80 PSI (I weigh 145 pounds, so I'm no clydesdale). I did find I need a higher pressure in a Sun M13 rim, that I thought was a copy of an old Mavic E I have, than I needed with the Mavic E. Even though they look identical, they apparently aren't, and the rim makes a difference.
Too have an wheight advantage over tubeless you have to use thin latex tubes like Challenge (55g) and these tubes loose to much air and are not suitable for 120km races or weekend rollouts. Starting with 80-100psi i guarantee you end up with 60psi after 3h ride and the you won`t be able to corner at high speeds and sprinting is impossible. And in case of a puncture, you are just out - dnf. With TL you loose about 10psi and finish with the bunch. In several races i didnt even noticed that i punctured.. The only downside with TL-tyres is that they won`t hold the high pressure after a handfull of punctures. Sometimes you get like 5 puncteres in 2 weeks and have to buy a new tyre and yes i tried several methods to repair them. Looking forward to up to a 28mm in the back and a pressure about 70psi, hope that the sealant can handle it.
I must be the only person who started on 28mm width tyres and ended up going narrower. I now tend to run 25/26mm tyres although I am 10-12 kg lighter now than when I ran 28mm. I also switched to tubeless 25mm from 28mm with tubes. I run around 70psi and find that works best and now I've used just the SRAM calculator to see what I should be running I have actually been running the correct pressures. So basically you should be able to 'feel' what is right as much as what science tells us. It just shows you need to take the time to experiment with your pressures to find what works best! As previous other mentions this is a great video delivered in a well thought out way! Thank you Simon.
I was put onto this by a neighbour last year and he’d known this for a while. I ride 28 32 and 35 and the improved comfort is noticeable. I can get away with 55psi on the front. By the way, have you ever thought of buying sensible bikes with mudguards? I have a photo of Merckx training in the 1970’s in the rain and guess what, he’s got mudguards on!!!!
Very interesting. The suggested pressure range for my 26mm wide tires is 100-120 psi. The SRAM suggests for my specs 70 psi front and 74 psi rear. Is that safe? Shouldn't we always get the tires at least at the minimum pressure suggested by the manufacturer?
I've been using this Sram tire preassure guide since it first appeared on GCN with introduction of the Zipp 303s wheels (if I remember correctly) a few years ago. I find the calculated preassures for road very good and stick to them. However, for gravel riding, the calculated value seems to me to be just a good starting point for like 50:50 split gravel and tarmac (maybe even more towards the tarmacy spectrum), I like to go quite a bit lower. For cyclocross and mountain biking, I also tried this calculator, but ended up pretty much not looking at preassure at all and base my inflation of the tires mostly on my experience about how much (I think) they should deform.
@gcn Excellent video and follow-up to the previous 28 vs 32 comparison. As a bigger rider (90+kg), riding on rougher and rolling hills routes, I jumped on the suggestions from this last video and equipped my Ultimate's Ultegra C50s with Continental GT5000 32s. Initially I ran them at 72psi and the result was slight, but a measurably faster "short ride" performance, but significantly faster "longer ride" performance. I attribute the latter to less cumulative fatigue from reduced road vibration, which allowed me to keep a higher pace for longer. Following on this observation and this latest video advice, I used SRAMs recommended tire pressures of 68-R/64-F, and the results were clear. So while Jan. weather here isn't conducive to long rides, my brief 1 hr scoot did feel faster, and I'm 100% confident this outcome will translate to even further performance improvements over 3+ hr rides. There might even be added benefits related to better/faster recovery and there is no denying the uptick in ride enjoyment and motivation.The takeaway is that fatigue reduction is a key benefit of larger tires, that hasn't received the attention it deserves - albeit in part because it is harder to quantify. Lastly, I'll go one step further and say that the fatigue reduction benefit is doublely important for us 40-plus riders. Do you agree with this last point Simon and Dan? 😉 Cheers from Toronto, Canada
For big guy 36H rims, 32 tires are minimum for city or long runs. Otherwise due to vibration rims, spokes, huns, bearings will go. Lower pressure will collect glass punctures. Consider stem and seat dampers. Mine front 90-100 psi, rear 70 psi. Feels faster rolling (less effort) and butt not getting much kicks.
great content, I'm running 90 psi on the back, 87 psi on the front with 25mm clinchers that measure 26mm (I weigh 170 pounds). I've lost 15 pounds in the last three years since I'm now so comfy and riding even more than when I ran 110 psi.
I'm really surprised tire pressures haven't been looked into much sooner. If you think about it, there's not much else that moves on the bike in terms of suspension (road bikes), def not as much anyway vertically. You mentioned cross riders getting it right, and you're correct, cross race parking lots are a meca of tire pressure geekery.
I think it was long limited by tyre widths and tubes. If you go too low with a tube the pinching risk is too high. Tubeless has allowed much lower pressures than most roadies would have dreamed of.
I took a 17-year break from cycling, and now I am in my 50s. I have taken up cycling again just for physical and mental benefits. When I used to race in the 80s and 90s, I ran 100 psi in my 21mm tires, and my race weight was 135 to 140 pounds. Ironically, I used to put 80 psi for training, thinking I was making to training harder. Now I am 175 lbs., and the recommendation is to have my tire pressure in the 80s. It is just amazing to me from watching GCN videos how much technology has improved and changed cycling! Great video Simon!
I had a friend who did the same; he used to race and took about 17-18 years off the bike to raise a business and family. When he pulled his old steel race bike down from the garage wall, the tubular tires still had air in them!. Solid glue up job! Now he's on a high end carbon Cervelo.
I'm not worried about comfort. If I was, I'd take a train on my journey. I will still use higher pressures and be happy with that. Getting through a ride sans flats is a top priority. If you get flats, you will likely not finish the race or be in contention for any placings. I run higher pressures on the mountain bike too. I've had to many snake-bites. As a Clydesdale, my experiences are different than most of you.
I am riding the Zipp Firecrest 303 hookless rims with Pirelli P zero race TLR 700 x 28. The frame is a 2022 Cannondale Supersix hi mod EVO frame. I weight 71.6 kg and 73 years old. I live in an area with a lot of mountains and rough paved roads. Tire pressure: I started with the recommended SRAM tire pressure of 54 and 57 psi. After a month of riding trying a lot of different pressures, I prefered front 51 PSI, rear 53 psi. The ride is extremely compliant and this bike feels much faster than my older bike. Both bikes weighed 16 lbs. I do ride with a power meter so I know my power output. This rim and tire setup have such a tight air seal, I never had to add any additional Orange Seal sealant the entire Zipp season. 2000 miles on old bike with 28 deep rims and 19 internal width with 25 x 700 tires with 80 psi and 2000 miles on the Zipp wheels. So it is not apples to apples.
Thanks Si. Interesting analysis. Tried out the SRAM estimator... for my rims and wheels (25s) i usually pump to 90-100 but it's suggesting 75 and 80. I will try this out.. but as you imply that is against the grain of 40yrs+ of cycling experience of hard is fast. By the way, where was that road? Thx
Good luck. I did same with my tubeless 25s a year and some ago. Not sure if I am faster because of it but at 80 it felt like a different and much more enjoyable bike. Never went back.
Been riding on and off since late 80's. My last bike ran 23mm tires at 100psi with thorn resistant tubes. My new bike is a flat bar road bike. It came with 28mm tires. I switched to 25 mm tires, thorn resistant tubes and 80psi. Love it.
Having used the SRAM tyre pressure calculator in the past to try and optimise my 25mm tyre pressures (with inner tubes) I found that the suggested pressure for me was quite low (~80psi). I tried it, and frankly the only thing I seemed to get out of it was a significant increase in pinch flats. This may have been confirmation bias, but I've gone back to 100psi, but may drop to a compromise of around 90psi when the weather clears up. I have a suspicion that far more people are still running tubes than tubeless based on a GCN app survey I saw recently, so it becomes very hard for a large number of people to really translate this advice into practical results in my opinion. Still very interesting though.
It could be that merry old England doesn't have the same proliferation of potholes that chipseal seems to attract in countries w/ less rigorous maintenance.
@@GeekonaBike roads in the UK are a mess - at least the ones you'd cycle on. Major roads get fixed and are OK. Super low pressure is only a thing for tubeless, but even for tubed I run relatively low - 75psi on a clincher setup!
I'm still riding with tubes, partly because I don't have the money for different wheels, tyres etc. Partly because I haven't had a flat in 4000km so all that messy sealant business seems like a lot of extra effort.
I mostly run 700C sew-ups still. From online calculator from SIlca, with my weight and the bike being around 215 lbs and me running 21mm wide tires (tires say 23 but measure 21). Computer recommends 120 psi. If I bump the tire width on the calculator to 23mm it says 110 psi. Which is mainly what I've run for 40 years. No changes. I neve run a tire wider than 25 as they won't fit my bikes.
I have 700x32mm tires on my road bike and I am 6'4" 240lbs. I was riding at 70 psi, out of a maximum of 100 psi. I noticed when I went to 90 psi the riding was MUCH easier and faster. Now granted, it is harder but the difference in tire pressure made quite a difference in watts expended to go the same speed.
I find it interesting how used you get to the softer pressure. Having ridden 50-60psi for a few years now, even going up to 70+ has become almost unbearable!
Vwey helpful. Im running 25 tires on 19mm rims. Cant go any wider. Got bike used and it came with 23mm tires. Did 145km on mixed surface road and light gravel and omg was that torturing amd exhausting. Plus was 35C. Got home, switched to 25mm. Running 5-6bar. Game changer. SRAM calculator suggests 5.5-6.5 bar gravel/road. This feels right as well compared with 100 psi (8? Bar) vibration hell
best gcn tech video for some time....thanks...running tubeless 25's at around 75psi as an 81kg rider......i find that going below 70 makes me feel less secure cornering, as if the tyre is squirming around...will think about it a little more carefully though..
13:23 As always, Simon an interesting and entertaining video. I wouldn’t argue with any of your explanations about the effects of pressure and tire/rim width, but I’d like to emphasize that it is not only the effect of vibration of the rider, but importantly also the vibration of the bike itself that are factors in rolling resistance. A tire at high PSI is micro-deflected more than a tire that is softer, which causes power loss. Any energy used to push the bike upward (hop)is energy not available to move the bike forward.
I ride hybrids on very potholed roads and in the last couple of years despite using 1.75" and 2" tyres I've had a couple of rim failures, both shortly after hitting potholes. I've now dropped the tyre pressures from the max on the tyres (50 to 60 PSI) to 40 PSI to put less stress on the rims. I've never had a rim failure on my mountain bike where I've always use lower pressures.
How low can GCN go because of propaganda Propaganda with low pressure started when tubeless technology didn't work at high pressure, because high pressure throws all the liquid out without plugging the hole, so they thought of inventing hookless rims that oblige you if you don't exceed 60/70psi otherwise the tire comes out from the rim, problem solved with tubeless tires This is my opinion
You do realise that invention and science works by testing under fixed parameters and discoveries are made along the way yes? Are you suggesting that every pro tour team using tubeless at low psi's are doing so because of propaganda?
I've found that running the lower pressures some are suggesting I start flatting far too often w/ GP 5000's and regular tubes. When I increase the psi I flat far less often. Lots of goatheads (stickers) on the roads here. Comfort, speed, or sitting on the side of the road patching.
On this topic I also run the front tire at a slightly lower pressure than the rear tire. The weight bias is not generally 50/50 on a bicycle and should be considered in the strategy. This will very depending on the bike, the rider and prefered riding position. With some experimenting the optimal pressure for each tire can be found. I've been recommending this to customers for a long time and it seems to been a good thing. Now on this subject I also tend to run different tires front and rear too because how differently they function on a bicycle and this strategy has served me well for decades. The front tire I chose is usually sticky , deeper tread, more supple and less flat protection (Vitoria cotton). The rear tire usually more robust with a lower rolling resistance and better flat protection (Continental or Vitoria polyester type). I'm a bit surprised that this hasn't been experimented more . I learned this from experimenting ( a benefit of working in a large bicycle shop lots of good take offs available) with all the different types of bicycles that I ride and worked well. I'm really glad to see more wide tires on the market I've been using wider tires for decades now and has served me well. I hope the market will adress the difference between front and rear tires too. Thanks
I like a lot of us always pumped to max on the tyre, rock solid. Since I have seen vid's fron GCN and others on pressures I have reduced them on my vintage tourer (1963) my MTB and road bike and with the aid of Strava my times have improved along with comfort. Still trying out different pressures but as this vid says too low is as bad as too high. Keep up the good work and hope you did not get too wet and cold
Option #1. Just use the minimum that the manufacturer recommends for your fave tyre. Option # 2. Test various pressures from minimum and go up from there until you're happy with feel and performance.
I actually helped with some testing 40years ago where we towed a bike and measured the power that it took. We were trying to prove the data in a paper that had been published that suggested that the tire should compress 15-30% depending on the road surface. I have been riding what were considered 'too low' of pressures in 23/25mm tires for decades. My hands and butt like it. I am moving to sider tires these days but using old frames and rims there are limits as to how wide I can go.
Thanks for the "tire pressure guide". Definitely bookmarking this page. According to it, I was already running my front tire at the optimal pressure (80) and can push my back tire 6 more PSI (86).
On my retro carbon carbon fiber 10 year old road bike with Conti GP 5000's 25mm (clinchers) and regular old butyl rubber inner tube, I ride them at 100-105 works well for me. The roads are crap around here, and running lower pressure results in pinch flats. Running at 110 - 120 (not done by anyone these days ) is asking for trouble on hot descents with rim brakes, and black aluminum wheels, makes me nervous having had a blow out due to ultra high pressure. (Ka BOOM !! - crash boom bang) Now on my Gravel Bike with a Tubeless setup I ride with 36cm knobby tires, at 60psi which is pretty safe on the deteriorated rural hills of Sonoma county, and offroad double track true gravel roads.
Just watched this, didn't realise it was an older video until after I finished... I did a similar test about 5 years ago when I bought my gravel bike with 650B x 47 tubeless tyres. On-line pressure calculators weren't around so I was initially guided by the tyre sidewall recommendation of minimum 40 psi. I didn't have a power meter, so tested by repeated rolls down hill on well-worn chip seal, 700m @ average 5%. I was also interested in traction, so also tested up and down a loose gravel fire trail 400m @ average 14%. Started at 50 front/ 55 rear and dropped by 5 psi increments maintaining +10% on the rear. Rode each pressure 3x and averaged the result. Fastest downhill was at both 35/38 and 30/33 psi, didn't get significantly slower until 20/22 psi. SRAM calculator suggests 33.5/35.6 so my results agree. On the fire trail, the first couple of runs I was spinning out on the climbs and descents were downright scary - traction kept improving with every drop down to 15/17 psi. Wasn't game to run any lower but by that point the tyres were getting a bit too squirmy on corners.
After watching this video, I did as you said and described. I ride 700x25. Normal tire pressure for my rides are 100psi front, 110 in rear. According to scram tire guide, I should be 75 psi rear, 71 psi in front. My weight was also calculated in this equation. Which is 176 lbs. I reside in Orlando Fl. Early morning ride on the West Orange Trail. Definitely will hit you up on this ride. 32 miles short ride.
What about hysteresis vs the specific heat of the rubber vs temperature vs water conditions? I think a retest in The Outback at around 50C is in order.
Great video. Retired from racing now, but I always raced my state's time trial championship on 18 mm or 20 tubulars pumped all the way up to150 psi (at least the 40 km course had a smooth road surface). But evidently 25 mm tires pumped to just 60 psi are actually faster. What a massive difference. So soon old and so late smart.
i love my 32mm tubeless tyres when I was in London rolling around at 50-55psi however since cruising and climbing around spain I'm finding myself needing closer to 70psi, it feels more predictable on the descents.
Tyre pressures are the free upgrade everyone should make. I'm still on rim brakes with room for no wider than 25mm. My rim width is 20mm and with a tubeless setup (Vittoria Rubino Pro graphene) my recommended pressures are 73.3 front and 78.3 rear. If travelling light I run slightly less but if I am going to be laden with shopping in my panniers I pump it up a couple of psi. And I have observed that tubeless winter tyres at the optimum pressures are noticeably faster than 25c summer tyres (GP4000 SII) with butyl tubes at 90psi I was previously using.
@@gcn It also helps that many of the roads I ride are either a patchwork quilt of rough and badly repaired tarmac or are surface dressed with the roughest stones available, not much of the buttery smooth stuff around.
@@gcn Tell me about it 🤣🤣🤣 even when the local council does a proper resurface job it looks like it's been flattened by a steamroller who has had a few too many of Dan's Mineral waters!
It would be interesting to do the same test by addressing the vibration attenuation via different frame and fork materials. Same wheelset on a Reynolds 531, Columbus Max / EL OS / SL, Litespeed or Merlin Titanium, Tubed and moncoque carbon frame dujour. Nice video and nice bio positioning too. Thanks!
We could really get into it and do the test with nice conventional clinchers with latex tubes, nice cotton open tubulars, and tubulars. Then we can take a real trip and do the test with different types of spokes, spoke counts and rim materials.
What tyre pressure do you ride? 🧐
Max. What slows me down really are the snake bites. Everybody should try riding a flat sheet of ice. No vibration, very little rolling resistance, astonishing speed.
@@stasacab On ice skates! sure
The lowest pressure that will keep me from bottoming out and destroying my expensive tubeless tires…
Thanks for the great video!
I have tested, tested and tested..
And for me the fastest combination is 23mm 110 psi front 120 psi rear??
But the problem is that you no longer want to find tires and rims that can withstand that much pressure?!
got recommended pressure of 4.6 bar front and 5 bar rear...i usually run 5.5 front and 6-6.5 rear so i'm not too far off (with tubes, 28mm)
Not only is the information well presented to both the technically informed and layman alike but the I just have to add the videography is absolutely amazing in this video! These amazing shots/angles/speeds we just can’t ignore how much effort it must have taken to produce this masterpiece. Well done GCN.
Thanks so much! That means a lot
It is "trust me bro" with no scientific testing, backed by the people saying disc brakes and heavier frames are faster.
Second the comment about the videography. Great work
Hear hear! As an occasional videographer myself, I'm very impressed.
Awesome presentation. Si's ever increasing nerd factor is beginning to impress me. His sunglasses are too small though
As a 50-something who's been road cycling since the 80s, I ran 20 or 21mm at 115-120psi for decades. Went to 25mm in 2018 but still put over 100psi in them. I'm down to around 80psi now, so I'm slowly adjusting to what the science says, but it's a slow process. I probably need new rims before trying 28mm - mine are from 2009 and came shod with 23mm tyres.
I feel my rear bottom out at 80psi, tyres rated for 110
I used the calculator and my weight shouldn’t really be bottoming it out
I also just like the feeling of 100-105 PSI
@@Ober1kenobi if you're going through new tarmac roads, top pressure is the way to go
Its good to play around and see what works best for you!
Same here. Narrow tires at very high pressures. Don't exactly miss that.
I’m old and arthritic and I find that 28mm road tyres at 90psi are my sweet spot 👌🏾
Where I live, the roads are terrible, but I have a bike that is capable of running 32mm tires, and it has changed my life. Running high volume at lower pressure has made riding much more comfortable, and I honestly don't feel any loss rolling resistance. Coming from a background of racing in the '80s to the '90s when skinny and hard tires were the norm, this is a great change! I'm happy that cycling is letting science take the lead over tradition.
I've been on tire pressure journey for about 1.5 years now - down from 120 to 80. So much more comfortable! This is best video on tire pressure I've seen yet - they key takeaway for me is to use the calculator to get into the right range, and then don't stress about it - you've shown that 5-10 lbs either way doesn't make that much difference. Take the Comfort...And don't forget - Resistance is Butyl!
Glad it helped! Let us know if experimenting works!
Worth a like for the Star Trek reference alone. ✨
I like higher pressures, still, after half a century of riding, but even in the heyday of skinny (18c) tires, 120psi was too hard. Mind you, I base that on cross-country treks mostly asphalt, but some gravel/crushed limestone (what's termed 'gravel' is slightly different UK to North Am, I'm a Cdn/Brit Dual). I found 100psi on the early Specialized 18c was at the top end of efficiency, sanity and durability (this was before polyaramid was used for puncture resistance) but even as I've increased tire size dramatically over the years (I'm using 4 Seasons 25c front, 32 rear), the front will be 28c next replacement) I bought into the 'lower is better' spiel, only to inch back up in pressure to a 'feel' of optimal at about 70-80psi.
Something today's generation fail to include in the 'feel' of what is right is the frame behaviour. I ride a classic 531 frame which is very lively and comfortable. (I had the chain stays dimpled by a framebuilder to accept the 32c width) one of the best mods I've had done over the years.
Needless to say, I ride hooked and see absolutely no reason to want otherwise. Built up my last wheels a decade ago, they're still in superb shape. (Mavic A319s). Engine still going exceptionally well @74yrs.
Si, as a nearly 60 yr old roadie, I’ve always used relatively narrow rubber 25-28mm at higher pressures. However, I’ve recently bought a Giant Revolt running hookless rims and CADEX AR tyres at 40 psi and the difference on ‘normal’ (i.e. potholed) roads is incredible - everything is better, speed, comfort, grip, and not one puncture all winter….I was very sceptical before changing, but wouldn’t go back to ‘narrow’ high pressure rubber now. If you’re a racer, I get that you still want narrow tyres at high pressure, but for most of us hobby cyclists who want to ride for fitness and enjoyment, low pressure tubeless would seem much better on rubbish UK roads. Love the videos, keep them up! Rich
I've been running 28c Conti GP5K at 70 psi. I use latex tubes which lose air slowly so I pump up and check pressure before every ride. Sounds tedious but it's my ritual and the added benefit of meticulous awareness of tire pressure is that there are no surprises when cornering fast downhill.
I don’t get how people can go for a ride without checking their air pressure, except on my daily bike (very short and slow ride). I totally agree with you, it’s a matter of security.
"Cumulative fatigue reduction on longer rides" is another important benefit. This was mentioned in another post and it makes so much sense I ordered a set of 32s just now. The marginal gains on short rides is nice, but the benefits for 100 or 162K rides should be much more significant!!!
I weigh 57 kg, and normally ride fondo or century on weekend. I run 32c at 50 psi, I tried 55 psi but the road chatter is atrocious. The road surface where I live left a lot to be desired. I tried Silca tire calculator and actually it suggets 52 psi.
Very true! For those long endurance rides, comfort it key 🙌 Would you still run 32mm for fast short efforts?
@@gcn Since I still have nearly new 28s, I would consider mounting them for a short TT on smooth roads, but the gains only barely outweigh the trouble.
@@jojoanggono3229 if you weigh 57kg why on earth are you running tyres that are nearly .5kg heavier. A 32 mm tyre is way to stiff and heavy for your weight. You could get the same comfort out of a 23 or 25 as the benefits of fat tyres diminish greatly the lighter you are.
@@gcn i switched to 32c from 28c due to the fact that most races I attend to are flat crits or flat 20 km rounds with multiple laps with many, many fast corners and wider tire with lower pressure gives me much more grip and confidence in cornering at a really steep angle. I never felt slower because of this tire choice, actually I'm riding faster cause the roads here are far from perfect and pristine.
Good video Simon, you got the theory about hysteresis vs vibration attenuation well dialled and explained it well. I've got a video series in production about the issue too. However for aero protocol, i couldn't get the hookless Zipp up to my control pressure due to the 5 bar limit. On my medium textured asphalt, a fixed-CdA test with pressure sweep showed 76psi to be fastest on my control tyre. Simple as that. For heavier riders on smooth roads, who don't want the aero and weight increase of tyre upsizing, hookless just isn't viable. And lets be honest, hookless is being pushed because its MUCH cheaper to mould and de-mould.
Glad to see the non enslaved enter the chat!
76 is actually quite low for your size. I don't remember your weight but you're like 195. It makes me think that I should drop my pressures a few psi more.
.. and hookless rims are supposedly not as structurally strong as hooked ones, although I guess that they are passing the UCI and other required testing. Would be great if you could comment on that.
I’ve done some Chung analysis testing myself.. and yes, on smoother pavement the optimal pressure does go up. BUT, since on smoother pavement the optimal pressure curve is flattened.. I got 20psi around the “optimal” pressure where the power differed by .5 Watts most of that span on the lower pressure side. So from a PRACTICAL point of view I’d take the .5W hit for better, traction, VASTLY better performance on any rougher patches might encounter, comfort , vibration related fatigue etc.. those 15psi don’t actually get u that much at the end of the day except in the case of a straight out and back TT on smooth pavement
@@Membrillo81 different tyre technologies have different side wall stiffnesses. For a 23 clincher 1psi per kg was the general rule. For a hookless it’s about 0.7 per kg. The hookless tyre is much thicker to maintain its shape.
I mostly pick my pressure based on absolutely minimizing flats, not performance. still riding 80-90psi on 28s at ~175lbs. (some of my bikes still don't have tubeless)
agreed. comfort is a luxury. preventing flats is a necessity.
I had to ride home with a lower pressure after a roadside repair the other weekend mainly because my emergency portable pump is crap! I was expecting to be slowed down by it a lot however on our rough county lanes it didn’t actually make as much difference as I expected and was a bit more comfortable! I am going to experiment with slightly lower pressure from now on.
In automotive industry we use coastdowns to measure frictional loses. Do it both directions to deal with wind effects. Similar to wahoo spin calibration but on the road.
I have tried lower pressure and there are other considerations as to why to use higher pressure for road ( in particular) and gravel. 1. I got far more punctures on lower pressure (tubes). 2. On lower pressures I didn’t like the feel of the back tyre which I was always checking to see if punctured. 3. The difference on performance are marginal and can be different from these controlled tests. 4. On road, thinner tyres are better to avoid punctures than wider (smaller contact point to get the puncture - along with higher pressure to reduce the contact point).
I ride 40 km 6/7
I did this for 4 years with 25mm tyres and punctured 0-5 times a week, i'd say on avg 1 flat every 2 weeks
Last year i rode 28mm and only had 3 flats :)
The 28mm tyre only went flat because of wearing down, I had to change the 28mm tyres 3 times in 1 year
On avg the 25mm tyres in those 4 years had to be replaced every 2 months.
This might be just me but i'd never go back to thinner tyres, they wear down alot faster and are very very easily punctured if you use tubes
Do note though, riding every day through every kind of weather no matter what. so my experience might be alot different than someone riding 1-2 times a week in good conditions
@@WeallAreAdults i had gator skin hardshell made in Germany Continental . Been in my cannondale super evo more than 2 years . Best tires ever !!!
@@ReNNEbab ill look into them, but i doubt any tyre would last 2 years with the milage i do weekly :D
After watching GCN videos during C19, I went tubeless and wide (32 mm GP5000), and used the online calculator setting up my new road bike last summer. The speed, feel and comfort of this is absolutely magnificent, It is also less problematic with short gravel sections with the road bike.
Great to hear!
Interesting. What online calculator are you referring to if I may ask?
What calculator is this?
@@MattPrego SRAM has a calculator online just search SRAM Tire pressure Calculator. Also Silca has a good one too.
GCN videos in the 19th Century???
I've been following the suggestions of the SRAM pressure calculator for several years. Speed isn't my top priority, but the increased comfort on long rides is well worth it.
Whatever works for you!
Only been riding 3 years, but as my bike (also of 3 years) came with 28mm tyres on 22mm rims, it seems I was reasonably lucky.
Been running at max pressure (8Bar) as a heavy rider (80-96Kg) but just followed this advice, with 4.4Bar in the front and 4.7Bar in the rear and TBH I’m not even bothered about the speed, the comfort difference is incredible.
Fundamentally I agree with what you suggesting Si. Lower pressures are more comfortable and in most cases faster, esp. on ‘bumpy’ UK roads… but I would add 3 points to consider:
1. TPI rating of a tyre. Lower TPI tyres (120 or lower) with heavy duty butyl tube will ‘vibrate’ much more than a 330TPI tyre with latex tube at the same pressure, hence be slower…
2. Tyre pressure for training vs. racing. I add around 10psi to my race tyres purely for puncture protection. Too many times I suffered an unavoidable flat in a peloton, simply because you can’t see far enough in front to avoid it, unlike in training.
3. And finally, how ‘low you dare to go’ with tyre pressures, is dictated by how much you love/care about your rims. If you run expensive carbon clinchers like myself, then you’ll think twice running them too low. Once I wrecked both, front & rear rims in one go by hitting a nasty & deep pothole on a group spin. There’s a reason why Pro cyclo-cross riders are still running tubulars with the super-low pressures required to be competitive. Tubeless wouldn’t hold that pressure over that kind of bumpy terrain
> I add around 10psi to my race tyres purely for puncture protection
Yeah that's an important point to consider for the commuter cyclist.
thanks for the excellent tips. I don't race but can really appreciate them. My next tyres are going to be the Continental Ultra Sport III which are 180TPI, still doubtful whether to use latex or a TPU inner tube, but most probably latex
"I add around 10psi to my race tyres purely for puncture protection."
I thought higher pressure made flats more likely?
@@mindstalk
Higher tyre pressure will avoid “snake bite” when running an inner tube. It’s when you puncture the inner tube in 2 places by full decompression of the tyre in one spot and contact with the rim.
There’s a reason why ‘back in the day’ guys were running 120psi in 23cc tyres on narrow rims… to avoid snake bite punctures…
With modern wide rims and tyres, it doesn’t happen as much, but it’s important to match the tyre size to rim width to avoid the “lightbulb” shape that increases the snakebite chance. As a bonus it will be more aero at the same time (tyre width that’s flush with the rim).
Tremendous video. I’ve been giving this a lot of thought lately. I now realize that for years, I’ve been over inflating my tires. I used to run 80 psi irrespective of conditions. When the weather improves and I can move from the trainer to the road, I’m going to dial it down to 60 psi and see how that goes.
I follow recommendations from the Silca tyre pressure calculator, never had a problem.
I used to run 25mm tires but tried 28mm and ended up loving them. They're just more comfortable and smooth and at least give me the feeling that I'm going faster, but who cares when it just feels better. So, I've swapped all my tires to 28mm even if the rim is aerodynamically optimized for 25mm or the tire is heavier. That extra comfort just makes the ride much better. It's easier to dial in all my bikes to feel similar even though they are different brands since I have more volume to play with. Running them at 60-70psi seems to be my sweet spot, when I used to pump my 23mm up to 110psi. After riding gravel I've become more aware of tire pressure on the road and it makes a big difference in ride quality.
Try 32mm now! It's twice as much comfortable as 28mm and even faster.
@@goku445 I actually ride 30mm now and run 32mm on my daily cruiser
WOW! I tried SRAM's calculator and it recommends 59psi & 63 psi (front / rear for reinforced) That's below or at the minimum pressure for Bontrager AW3. I ride at 80 psi or 5.5 bar to avoid any issues of the tire rolling on a turn. If I'm on my roller trainer, I max it out.
Your jokes Si leave me totally deflated.
Tyred of this sort of joke.
I need some air.
@@tquest1 🙈
@@georgeblackwell4327 🙈
It’s a slippery slope (rolling resistance joke)
One of the most informative GCN videos I've ever watched. Super interesting and really well presented. Congrats!
Great to hear you enjoyed it so much 🙌 What else should we cover?
Amazing colour grading. Looks awesome guys!
Thanks! Somehow we managed to make soggy British weather look good 😉
Calculator suggests I should run 73psi (im sub 60kg on 23m tyres). I run 120 normally (mainly so I can go many days until its around 90psi). Last time I went out with 70ish psi on 25mm tyres I had a double puncture (pothole, same road as ever). Not tubeless, but needless I will continue to run 100+ on 23 or 25 tyres.... im not racing, im not chancing punctures. And neither am I switching everything over to tubeless and its hassles. Tubes have had very little issue over the decades, im not changing.
Both the SRAM and Silca calculators suggest I lower my pressure by 5 PSI front and rear, down to 85/90 from 90/95. I recently went down from 95/100 and noticed a different in comfort, but not speed. I'll try this new PSI and perhaps a pair of Si's Fearless Fly glasses and see if that works!
I wonder about the negative power loss if any, while sprinting out of saddle on low pressures. Kind like how suspension absorbes power vs locking suspension out for better power transfer.
Worth noting that the weight you put into the tyre pressure calculator should be your "system weight" which is the weight of the rider + kit + bike + any other items you might be carrying (bottles, tools, spares, etc.).
Yep!
Good point!
Actually, the Zipp calculator has two fields for weight, one for the rider and one for the bike.
@@jefferycampbell2243 yes, so you’ll need to include the weight of anything extra you’re carrying on the bike part or your weight part. Often I’ve got a pannier bag with work stuff with me
Maybe only consider half the weight of your bottle, you'll drink it right?
I run pretty close to the Sram calculator value at 30 psi on 40c tubeless tires on my monster cross bike, they list ~36. Works well on and off pavement. I've had other road cyclists let me know I had a tire going flat as they passed me.
You mentioned something at 17:35 that is the key to wider tires. If you don't have the "newer" type wheels with wide rims, your cornering at lower pressures will feel horrible with 28mm tires.
Streight line riding will feel fine with old school wheels and low pressures and wide tires, but you'll have to slow down in turns. It will be like going through a turn at high speed with a front tire going soft with a slow puncture.
Did you try 28mm tire on narrow rim? How narrow was it?
The jump from 25 to 28s is something you notice for cushioning effect.. Prob just new rubber against tired old worn out tyres is also something to watch out for , state of the casings etc.. type of tyres treaded trainers against smoother Summer jobs . Big differences all around before you even get on to pressures.
For weekend warriors going as low as possible is worth a try. The difference in comfort is way more beneficial than the small loss in speed in my own experience. I ride 28’s between 40 and 50 psi at 85kg’s and I love it.
I do not worry about speed. But I do worry about getting a flat. Harder tyres protect a lot better against sharp objects entering your tyre.
@@PaintrainX have you tried 70-80psi with 28c tyres?
@@PaintrainXnot really
@@PaintrainX have you ever heard of mtb? we run wayy lower preassures even in the days before tubeless we did and we rude terrain with sharp rocks and stuff.
@@SimonBauer7 MTB tyres are totally different. They've got a lot bigger diameter and a thicker surface with rough profile. Same goes for cyclecross btw, so that was not a good point from Si. Road tyres are much more fragile. With lower pressure you run a big risk of objects wedging in or even the tyre pushing through on the rim on a bump.
😊 I have these Zipp 303 Firecrest wheels and fitted the Tyrewiz as I had pressure anxiety running such low pressures. Very happy with the results.
Well done Simon! I really enjoyed this one. I started on the lower pressure about a year ago and have had quite a few arguments about it with others. I think this video says it all.
Thanks Si - GCN’s ‘in-depth’ videos always get me thinking especially as I still consider myself a newbie. The SRAM and Silca guides (Silca prompted by another comment) agree on my front tyre. SRAM suggests 2.7 psi more on my rear tyre. The difference seems marginal. I’m not expert so I think I’ll go with the SRAM guide.
I think there is an issue with highspeed cornering stability, pinch flats when using tubes, and tyre pressure. Personally I am around where Si said he was 50-60PSI on calculators with 28mm tyres, reality is I run more like 70-80PSI to stop some of the previous issues, the tyres just feel less reassuring when getting down below 60PSI, though admittedly they do dampen more vibrations.
I find you get more grip including cornering with lower pressures (like when I race cyclo cross). If its wet out, as a rule I'll lower pressure by 3-5psi.
Is the opening green-screened or filmed in front of a backdrop? Maybe first 20 secs? Also the bit at 1:05. The background and lighting on the bike look different.
used that SRAM gauge when I flipped to tubeless and I can definitely tell the difference. As an old timer that ran pressures of 120 to 130, running 28's at 58 lbs screws with my brain, but, I enjoy long rides a lot more now.
Which tubeless tyres are you running at less than 68psi? Scwalbe, Continental, Pirelli all have minimum pressures 68 or higher.
@@tobycolin6271 Pirelli P Zero Race TLR
@@justsomedude7556 the minimum recommended pressures on my tlrs is 65 psi. I have to run mine with tubes at 95psi as the max tubeless pressure isn’t enough to make the sidewall stif enough at 80psi tubeless or me.
@@tobycolin6271 You must have a very narrow rim width and smaller width tires. I can see running 25's in higher pressures. The Pirelli's have a very stiff sidewall and even on the rims with a narrower width I have, I generally run in the upper 60's. I will edit to say, the wheels I run at 58 have an internal width of 25, So running a 32mm tire on it, you can ride lower pressures. The wheels I used today, I ran at 58\62 due to rain in the forecast, with a 23 internal width and a 30mm tire, but I typically run 62\66
@@justsomedude7556 you didn’t say you were running 32mm tyres. The 28s squirm all over the place on normal 19mm width rims. Another example of the industry creating new tyre wheel combinations to sell more products.
I would also be interested in seeing a video done on climbing and descending with various tire pressures
Would you run low pressures for downhill? Get more grip around the corners 🤔
Great video! I've found tubeless tyres with a bit more with to completely change my experience on the bike. Much more confidence braking and cornering, but also MUCH more comfort. I think a lot of people would initially have the impression that it feels slower - but this is mostly just due to the road vibrations being absorbed so you have less perception of speed. I'm running around 65psi which is pretty close to where the SRAM calculator recommends and it gives a good balance between comfort and feel. Speeds on the bike are higher if anything.
That's great to hear! It can be a weird sensation at first but worth playing around with tyre pressure to find what works for you. 🙌
Much better explanation of vibrational losses this time than previous videos.
Essentially IT TAKES ENERGY TO VIBRATE YOUR BODY.. that energy has to come from somewhere.. any vibrations that make it past the tire, into the bike and into your body, that you feel is energy being taken away from the bike’s momentum rolling forward.. that’s where it comes from.. then eventually dissipated as heat into environment and lost.
For so long ppl have worried only about the attenuation of energy at the tire.. BUT not noticed that giant, energy attenuating meat bag sitting ON the bike.. a human body has a TON of hysteresis!
I run Continental gatorskins in a 33mm with no more than 50psi. Partly for comfort, but mostly because I'm 95 kilos and like my wheels to last as long as possible until I get to my target weight. The silca Calc was nearly spot on for road conditions.
Brave man, I really hate those tyres, so little grip in the wet...
Great tutorial! Thank you for sharing.e I have recently been gifted a Synapse disc alloy bike, and was wondering about tire width and pressure. This is a very informative tutorial with pointers to the excellent web tool to calculate pressure according to weight. I am considering 32s if they fit. My current bike - an excellent Scott, again alloy with carbon forks - came with 23s and, as I had been using mountain bikes pretty much all my adult life, I found it absolutely excruciating.
Living in Scotland, where the motorways are little better than bridleways, you really need to be looking at gravel tires, which is why I'm considering 32s.
I'm not so fussed about speed, and was glad to hear you mention the word 'comfort' - defo my priority!
I've had these rims Zipp 303 firecrests for almost a year. I hover around 190 lbs and run about 50psi in a 32mm Michelin tire. Was a weird transition for sure coming from regular tubed alloy rims which were 90-100 psi with 28mm tires. Really happy with the upgrade, definitely way faster and more enjoyable ride.
New wheels can make such a difference! Glad you're enjoying them
My old litespeed will only clear 25s and I got down to 215 lbs last summer. Preventing pinch flats is my number one goal 🤠.
If the new bike fairy pops by I'll consider this info (dear new bike fairy, really prefer the campy control levers for shifting. Thanks. )
Yes, everyone on here just assumes that you either have, or can run the stupid W-I-D-E rims and tires on an older frame, and not have to worry about those pesky pinch flats (and excessive 'squirm') from running 25s on an 18mm external width rim (like the Mavic Cosmic Elite rim brake ones I use), at pressures you could easily inflate them to by using your lungs, while weighing more than most big road (or even track) sprinters.
I'm still running at 100psi 25mm tires w. latex tubes. Bet it will trigger many xP
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But I also ride in an area w/ super smooth brand new Californian roads.
That probably works better for you than on the UK's pothole-littered roads 😂
#surfaceenvy
What a great video! I've been riding my touring bikes with pressures of 75 psi since the tires are rated from 50 - 85 psi. After doing a one week, 1,350 km adventure I lost sensation in my pinky fingers. The SRAM calculator stated my optimal tire pressure is 40 psi. I think I'll likely run 50 - 55 psi to observe the tire rating. That should improve comfort AND speed. Love it! Now, if I can stay away from the punctures from the wires in shredded transport truck tires. Thanks for the video!
Great video, turns out I was running way higher pressure than I needed to!
One kind request: could you please at least display the measures also in bar, kg, meters and so on? I had to run a converter every time. It is an international channel, most of nations use metric. Thanks!
I started experimenting instead of just fully inflating my tires back in 2015, and it was surprised by the results. On 25 mm tires, I found that the less air I had in my tires, the faster I would be able to go. My lower limit was actually determined by tire wear, rather than impact flats or speed. I found that if I didn't have enough air in the tires, I would start putting wear on the sidewalls of my front tire, because I would tend to take corners fairly hard (I rather enjoy doing that), so that's what determined my minimum pressure, which is what I run now.
I put about 80 psi in those tires. For reference, I and my bike together are about 180 lbs. I run folding Gatorskins with inner tubes.
What’s your impression on lower psi increasing rim pinching and tube puncturing? Enjoyed you and your video.
Tubeless made inner tube snakebites vanish. Being able to run the correct [much lower] tyre pressures is THE best thing about tubeless tyres.
OMG！I always push to the limit (which is 100psi), never heard of best tire pressure. After seeing this video, I went to the sram website and it suggested 66 front and 71 back. I'll definitely try this! Nice video!
4:30 Alex has fled to Australia rather than risking having to appear in this video and ride THAT road again.
I use Enve 5.6 with later and GP5000 25Mm that actually measure 27 when inflated.
For air, I use silca calculator and set front to 75PSI and rear to 80psi.
I've progressively been dropping my road tyre pressures. This is partly because I've lost weight, but also partly, I've been measuring them more. I used to run about 90psi front rear, and now, I'm down to about 55 - 60 front/rear with 28mm tyres (tubes). I suspect, as Si alludes to, people are running way too high a tyre pressure.
Its definitely a good idea to experiment to find what's best for you!
Agreed
I went tubeless on my road bike a couple of years ago and have been experimenting with tyre pressures a lot. Going on feel rather than measurements. I'm 80kg, 28mm Schwalbe Pro One tyres on hooked Hunt rims. My experiments have ended with 70psi back, 65psi front. Impressively I've just tried that SRAM calc and that's the pressure it recommends! Nice comfy ride, tons of grip, good rolling resistance. By far and away the biggest difference however has been going tubeless. Such a difference in ride/grip/confidence. And I've not had a single flat in 2 years.
That's great to hear! Hunt wheels are lovely to ride too 👌
Interesting comment about tubes and clincher tyres. I run 26mm tyres on 21mm internal rims (S-Works Turbo cottons, Alpinist CLX). I weigh 73kg and my bike is 6.65kg. I use latex tubes and run front 65psi and rear 70psi and have experienced not a single pinch flat or normal puncture over 12,000km on UK roads. I think there is a misconception that clincher and tubes pinch flat at lower pressures, that may be true at cyclocross pressure, but I have not found it to be case at typical tubeless road pressures. I think tubeless tech has a place, but I found it such a faff having to check sealant levels and roadside repairs are just plain hard with tight tubeless tyres. Good clinchers and latex tubes roll faster and weigh less as well.
Absolutely. With the right clincher setup you can ride for miles with no problems at all!
I run a similar setup as you describe. Pinch flats do still happen if you hit a REALLY big hole in the road. I've only had 2 pinch flats in the past 80,000kms or so, and both were severe impacts.
Agree. Bought some 25mm Conti 5000 tubeless, and couldn't even mount them on my Cosmic Carbone 40 rims. I must have wrestled with them for a couple of hours, trying all the tips to get them on, a bit of lube, leaving the tires in the sun, heating them with a hair dryer, a handful of levers, and finally gave up before I started hurling things about the room. Give me some lightweight tubes and regular clinchers any day.
I've run tubes and clinchers for years and only had 2 pinch flats in the last decade or so on the rough Canadian roads in about 80k kms.. Both from hard hits to a good pothole. I weigh 80 kg, bike is 8 kg and I usually run about 85 in the front and 90 in the rear.
I'm a bicycle commuter, and ride a lot in the dark in the rain, which does a good job concealing potholes, sunken water valve covers, and big cracks in the street. I've had several pinch flats, running over 80 PSI (I weigh 145 pounds, so I'm no clydesdale). I did find I need a higher pressure in a Sun M13 rim, that I thought was a copy of an old Mavic E I have, than I needed with the Mavic E. Even though they look identical, they apparently aren't, and the rim makes a difference.
Too have an wheight advantage over tubeless you have to use thin latex tubes like Challenge (55g) and these tubes loose to much air and are not suitable for 120km races or weekend rollouts. Starting with 80-100psi i guarantee you end up with 60psi after 3h ride and the you won`t be able to corner at high speeds and sprinting is impossible. And in case of a puncture, you are just out - dnf. With TL you loose about 10psi and finish with the bunch. In several races i didnt even noticed that i punctured.. The only downside with TL-tyres is that they won`t hold the high pressure after a handfull of punctures. Sometimes you get like 5 puncteres in 2 weeks and have to buy a new tyre and yes i tried several methods to repair them. Looking forward to up to a 28mm in the back and a pressure about 70psi, hope that the sealant can handle it.
I must be the only person who started on 28mm width tyres and ended up going narrower. I now tend to run 25/26mm tyres although I am 10-12 kg lighter now than when I ran 28mm. I also switched to tubeless 25mm from 28mm with tubes. I run around 70psi and find that works best and now I've used just the SRAM calculator to see what I should be running I have actually been running the correct pressures. So basically you should be able to 'feel' what is right as much as what science tells us. It just shows you need to take the time to experiment with your pressures to find what works best! As previous other mentions this is a great video delivered in a well thought out way! Thank you Simon.
I was put onto this by a neighbour last year and he’d known this for a while. I ride 28 32 and 35 and the improved comfort is noticeable. I can get away with 55psi on the front. By the way, have you ever thought of buying sensible bikes with mudguards? I have a photo of Merckx training in the 1970’s in the rain and guess what, he’s got mudguards on!!!!
Very interesting. The suggested pressure range for my 26mm wide tires is 100-120 psi. The SRAM suggests for my specs 70 psi front and 74 psi rear. Is that safe? Shouldn't we always get the tires at least at the minimum pressure suggested by the manufacturer?
You can always give it a go and see if it makes a difference? You may find what you're using already works best though!
I've been using this Sram tire preassure guide since it first appeared on GCN with introduction of the Zipp 303s wheels (if I remember correctly) a few years ago. I find the calculated preassures for road very good and stick to them. However, for gravel riding, the calculated value seems to me to be just a good starting point for like 50:50 split gravel and tarmac (maybe even more towards the tarmacy spectrum), I like to go quite a bit lower. For cyclocross and mountain biking, I also tried this calculator, but ended up pretty much not looking at preassure at all and base my inflation of the tires mostly on my experience about how much (I think) they should deform.
Great video - thoughts on completing the same tests without the rider knowing the pressure in each run? Improved non-biased results possibly?
2:26 incredible audio here. I don’t know how you guys get it so clean , but man!!
@gcn Excellent video and follow-up to the previous 28 vs 32 comparison.
As a bigger rider (90+kg), riding on rougher and rolling hills routes, I jumped on the suggestions from this last video and equipped my Ultimate's Ultegra C50s with Continental GT5000 32s. Initially I ran them at 72psi and the result was slight, but a measurably faster "short ride" performance, but significantly faster "longer ride" performance. I attribute the latter to less cumulative fatigue from reduced road vibration, which allowed me to keep a higher pace for longer. Following on this observation and this latest video advice, I used SRAMs recommended tire pressures of 68-R/64-F, and the results were clear. So while Jan. weather here isn't conducive to long rides, my brief 1 hr scoot did feel faster, and I'm 100% confident this outcome will translate to even further performance improvements over 3+ hr rides. There might even be added benefits related to better/faster recovery and there is no denying the uptick in ride enjoyment and motivation.The takeaway is that fatigue reduction is a key benefit of larger tires, that hasn't received the attention it deserves - albeit in part because it is harder to quantify. Lastly, I'll go one step further and say that the fatigue reduction benefit is doublely important for us 40-plus riders. Do you agree with this last point Simon and Dan? 😉
Cheers from Toronto, Canada
Some really interesting points there! Maybe a topic for a future video but definitely some food for thought!
For big guy 36H rims, 32 tires are minimum for city or long runs. Otherwise due to vibration rims, spokes, huns, bearings will go. Lower pressure will collect glass punctures. Consider stem and seat dampers. Mine front 90-100 psi, rear 70 psi. Feels faster rolling (less effort) and butt not getting much kicks.
great content, I'm running 90 psi on the back, 87 psi on the front with 25mm clinchers that measure 26mm (I weigh 170 pounds). I've lost 15 pounds in the last three years since I'm now so comfy and riding even more than when I ran 110 psi.
I'm really surprised tire pressures haven't been looked into much sooner. If you think about it, there's not much else that moves on the bike in terms of suspension (road bikes), def not as much anyway vertically. You mentioned cross riders getting it right, and you're correct, cross race parking lots are a meca of tire pressure geekery.
Its something that seems to be often overlooked but is still important!
I think it was long limited by tyre widths and tubes. If you go too low with a tube the pinching risk is too high. Tubeless has allowed much lower pressures than most roadies would have dreamed of.
I took a 17-year break from cycling, and now I am in my 50s. I have taken up cycling again just for physical and mental benefits. When I used to race in the 80s and 90s, I ran 100 psi in my 21mm tires, and my race weight was 135 to 140 pounds. Ironically, I used to put 80 psi for training, thinking I was making to training harder. Now I am 175 lbs., and the recommendation is to have my tire pressure in the 80s. It is just amazing to me from watching GCN videos how much technology has improved and changed cycling! Great video Simon!
Glad you liked it! Technology certainly has changed, hopefully for the better!
I had a friend who did the same; he used to race and took about 17-18 years off the bike to raise a business and family. When he pulled his old steel race bike down from the garage wall, the tubular tires still had air in them!. Solid glue up job! Now he's on a high end carbon Cervelo.
I'm not worried about comfort. If I was, I'd take a train on my journey. I will still use higher pressures and be happy with that. Getting through a ride sans flats is a top priority. If you get flats, you will likely not finish the race or be in contention for any placings. I run higher pressures on the mountain bike too. I've had to many snake-bites. As a Clydesdale, my experiences are different than most of you.
Great video ! Not sure if I missed it but curious if the tires were set up tubeless and the inner width of the rim ?
I am riding the Zipp Firecrest 303 hookless rims with Pirelli P zero race TLR 700 x 28. The frame is a 2022 Cannondale Supersix hi mod EVO frame. I weight 71.6 kg and 73 years old. I live in an area with a lot of mountains and rough paved roads.
Tire pressure: I started with the recommended SRAM tire pressure of 54 and 57 psi. After a month of riding trying a lot of different pressures, I prefered front 51 PSI, rear 53 psi. The ride is extremely compliant and this bike feels much faster than my older bike. Both bikes weighed 16 lbs. I do ride with a power meter so I know my power output. This rim and tire setup have such a tight air seal, I never had to add any additional Orange Seal sealant the entire Zipp season. 2000 miles on old bike with 28 deep rims and 19 internal width with 25 x 700 tires with 80 psi and 2000 miles on the Zipp wheels. So it is not apples to apples.
Thanks Si. Interesting analysis. Tried out the SRAM estimator... for my rims and wheels (25s) i usually pump to 90-100 but it's suggesting 75 and 80. I will try this out.. but as you imply that is against the grain of 40yrs+ of cycling experience of hard is fast. By the way, where was that road? Thx
Its good to experiment and see what works best for you, which may be what you're doing already!
It’s Torhole Bottom, in Somerset
Good luck. I did same with my tubeless 25s a year and some ago. Not sure if I am faster because of it but at 80 it felt like a different and much more enjoyable bike. Never went back.
Been riding on and off since late 80's. My last bike ran 23mm tires at 100psi with thorn resistant tubes. My new bike is a flat bar road bike. It came with 28mm tires. I switched to 25 mm tires, thorn resistant tubes and 80psi. Love it.
Having used the SRAM tyre pressure calculator in the past to try and optimise my 25mm tyre pressures (with inner tubes) I found that the suggested pressure for me was quite low (~80psi). I tried it, and frankly the only thing I seemed to get out of it was a significant increase in pinch flats. This may have been confirmation bias, but I've gone back to 100psi, but may drop to a compromise of around 90psi when the weather clears up. I have a suspicion that far more people are still running tubes than tubeless based on a GCN app survey I saw recently, so it becomes very hard for a large number of people to really translate this advice into practical results in my opinion. Still very interesting though.
It could be that merry old England doesn't have the same proliferation of potholes that chipseal seems to attract in countries w/ less rigorous maintenance.
@@GeekonaBike roads in the UK are a mess - at least the ones you'd cycle on. Major roads get fixed and are OK.
Super low pressure is only a thing for tubeless, but even for tubed I run relatively low - 75psi on a clincher setup!
Have to remember that wheel manufactures apps recommending low pressure is really just an effort to convince people to buy new wheels.
I'm still riding with tubes, partly because I don't have the money for different wheels, tyres etc. Partly because I haven't had a flat in 4000km so all that messy sealant business seems like a lot of extra effort.
I mostly run 700C sew-ups still. From online calculator from SIlca, with my weight and the bike being around 215 lbs and me running 21mm wide tires (tires say 23 but measure 21). Computer recommends 120 psi. If I bump the tire width on the calculator to 23mm it says 110 psi. Which is mainly what I've run for 40 years. No changes. I neve run a tire wider than 25 as they won't fit my bikes.
Having tried low pressure several times, I've found myself at zero PSI after the common pothole.
I have 700x32mm tires on my road bike and I am 6'4" 240lbs. I was riding at 70 psi, out of a maximum of 100 psi. I noticed when I went to 90 psi the riding was MUCH easier and faster. Now granted, it is harder but the difference in tire pressure made quite a difference in watts expended to go the same speed.
I find it interesting how used you get to the softer pressure. Having ridden 50-60psi for a few years now, even going up to 70+ has become almost unbearable!
You never go back do you 👀
Vwey helpful. Im running 25 tires on 19mm rims. Cant go any wider. Got bike used and it came with 23mm tires. Did 145km on mixed surface road and light gravel and omg was that torturing amd exhausting. Plus was 35C. Got home, switched to 25mm. Running 5-6bar. Game changer. SRAM calculator suggests 5.5-6.5 bar gravel/road. This feels right as well compared with 100 psi (8? Bar) vibration hell
Interesting video, especially like the dedication to the science by wearing the safety goggles while riding.....
Safety first 🦺
😅
best gcn tech video for some time....thanks...running tubeless 25's at around 75psi as an 81kg rider......i find that going below 70 makes me feel less secure cornering, as if the tyre is squirming around...will think about it a little more carefully though..
I thought covid restrictions were lifted, you can safely remove the face guard Simon.
😂😎
13:23 As always, Simon an interesting and entertaining video. I wouldn’t argue with any of your explanations about the effects of pressure and tire/rim width, but I’d like to emphasize that it is not only the effect of vibration of the rider, but importantly also the vibration of the bike itself that are factors in rolling resistance. A tire at high PSI is micro-deflected more than a tire that is softer, which causes power loss. Any energy used to push the bike upward (hop)is energy not available to move the bike forward.
I ride hybrids on very potholed roads and in the last couple of years despite using 1.75" and 2" tyres I've had a couple of rim failures, both shortly after hitting potholes. I've now dropped the tyre pressures from the max on the tyres (50 to 60 PSI) to 40 PSI to put less stress on the rims. I've never had a rim failure on my mountain bike where I've always use lower pressures.
I think I counted the word "Zipp", 74 times in this paid for promotion.
Running 60PSI on my 32mm Gravelking slicks on Chris King GRD23 wheels. Amazing ride and speed
How low can GCN go because of propaganda
Propaganda with low pressure started when tubeless technology didn't work at high pressure, because high pressure throws all the liquid out without plugging the hole, so they thought of inventing hookless rims that oblige you if you don't exceed 60/70psi otherwise the tire comes out from the rim, problem solved with tubeless tires
This is my opinion
You do realise that invention and science works by testing under fixed parameters and discoveries are made along the way yes? Are you suggesting that every pro tour team using tubeless at low psi's are doing so because of propaganda?
They need to sell the technology to newbies, so telling them lower PSI will give you SPEED when you use tubeless.
the bike industry is pushing all these so called 'innovations' where nobody is waiting for, it comes to a point where it gets annoying......
I've found that running the lower pressures some are suggesting I start flatting far too often w/ GP 5000's and regular tubes. When I increase the psi I flat far less often. Lots of goatheads (stickers) on the roads here. Comfort, speed, or sitting on the side of the road patching.
On this topic I also run the front tire at a slightly lower pressure than the rear tire. The weight bias is not generally 50/50 on a bicycle and should be considered in the strategy. This will very depending on the bike, the rider and prefered riding position. With some experimenting the optimal pressure for each tire can be found. I've been recommending this to customers for a long time and it seems to been a good thing. Now on this subject I also tend to run different tires front and rear too because how differently they function on a bicycle and this strategy has served me well for decades. The front tire I chose is usually sticky , deeper tread, more supple and less flat protection (Vitoria cotton). The rear tire usually more robust with a lower rolling resistance and better flat protection (Continental or Vitoria polyester type). I'm a bit surprised that this hasn't been experimented more . I learned this from experimenting ( a benefit of working in a large bicycle shop lots of good take offs available) with all the different types of bicycles that I ride and worked well. I'm really glad to see more wide tires on the market I've been using wider tires for decades now and has served me well. I hope the market will adress the difference between front and rear tires too. Thanks
I like a lot of us always pumped to max on the tyre, rock solid. Since I have seen vid's fron GCN and others on pressures I have reduced them on my vintage tourer (1963) my MTB and road bike and with the aid of Strava my times have improved along with comfort. Still trying out different pressures but as this vid says too low is as bad as too high. Keep up the good work and hope you did not get too wet and cold
That's great to hear! Always good to experiment with your setup to make sure you're getting the most out of it.
I run 35mm on my road bike! Still runs fast and extremely comfortable on Duluth MN rough roads
Option #1. Just use the minimum that the manufacturer recommends for your fave tyre.
Option # 2. Test various pressures from minimum and go up from there until you're happy with feel and performance.
I actually helped with some testing 40years ago where we towed a bike and measured the power that it took. We were trying to prove the data in a paper that had been published that suggested that the tire should compress 15-30% depending on the road surface.
I have been riding what were considered 'too low' of pressures in 23/25mm tires for decades. My hands and butt like it.
I am moving to sider tires these days but using old frames and rims there are limits as to how wide I can go.
Thanks for the "tire pressure guide". Definitely bookmarking this page.
According to it, I was already running my front tire at the optimal pressure (80) and can push my back tire 6 more PSI (86).
On my retro carbon carbon fiber 10 year old road bike with Conti GP 5000's 25mm (clinchers) and regular old butyl rubber inner tube, I ride them at 100-105 works well for me. The roads are crap around here, and running lower pressure results in pinch flats. Running at 110 - 120 (not done by anyone these days ) is asking for trouble on hot descents with rim brakes, and black aluminum wheels, makes me nervous having had a blow out due to ultra high pressure. (Ka BOOM !! - crash boom bang)
Now on my Gravel Bike with a Tubeless setup I ride with 36cm knobby tires, at 60psi which is pretty safe on the deteriorated rural hills of Sonoma county, and offroad double track true gravel roads.
Just watched this, didn't realise it was an older video until after I finished... I did a similar test about 5 years ago when I bought my gravel bike with 650B x 47 tubeless tyres. On-line pressure calculators weren't around so I was initially guided by the tyre sidewall recommendation of minimum 40 psi. I didn't have a power meter, so tested by repeated rolls down hill on well-worn chip seal, 700m @ average 5%. I was also interested in traction, so also tested up and down a loose gravel fire trail 400m @ average 14%.
Started at 50 front/ 55 rear and dropped by 5 psi increments maintaining +10% on the rear. Rode each pressure 3x and averaged the result. Fastest downhill was at both 35/38 and 30/33 psi, didn't get significantly slower until 20/22 psi. SRAM calculator suggests 33.5/35.6 so my results agree.
On the fire trail, the first couple of runs I was spinning out on the climbs and descents were downright scary - traction kept improving with every drop down to 15/17 psi. Wasn't game to run any lower but by that point the tyres were getting a bit too squirmy on corners.
After watching this video, I did as you said and described. I ride 700x25. Normal tire pressure for my rides are 100psi front, 110 in rear. According to scram tire guide, I should be 75 psi rear, 71 psi in front. My weight was also calculated in this equation. Which is 176 lbs. I reside in Orlando Fl. Early morning ride on the West Orange Trail. Definitely will hit you up on this ride. 32 miles short ride.
What about hysteresis vs the specific heat of the rubber vs temperature vs water conditions?
I think a retest in The Outback at around 50C is in order.
Great video. Retired from racing now, but I always raced my state's time trial championship on 18 mm or 20 tubulars pumped all the way up to150 psi (at least the 40 km course had a smooth road surface). But evidently 25 mm tires pumped to just 60 psi are actually faster. What a massive difference. So soon old and so late smart.
i love my 32mm tubeless tyres when I was in London rolling around at 50-55psi however since cruising and climbing around spain I'm finding myself needing closer to 70psi, it feels more predictable on the descents.
Love your Videos at these rough and unconfortable conditions in these beautiful and mystic landscape! Greetings from Germany!
Thanks! The roads here definitely are rough and uncomfortable at times 😅
Tyre pressures are the free upgrade everyone should make. I'm still on rim brakes with room for no wider than 25mm. My rim width is 20mm and with a tubeless setup (Vittoria Rubino Pro graphene) my recommended pressures are 73.3 front and 78.3 rear. If travelling light I run slightly less but if I am going to be laden with shopping in my panniers I pump it up a couple of psi. And I have observed that tubeless winter tyres at the optimum pressures are noticeably faster than 25c summer tyres (GP4000 SII) with butyl tubes at 90psi I was previously using.
That's an interesting observation! It's crazy how much of a difference tyre setup can make.
@@gcn It also helps that many of the roads I ride are either a patchwork quilt of rough and badly repaired tarmac or are surface dressed with the roughest stones available, not much of the buttery smooth stuff around.
Welcome to the UK 😉
@@gcn Tell me about it 🤣🤣🤣 even when the local council does a proper resurface job it looks like it's been flattened by a steamroller who has had a few too many of Dan's Mineral waters!
It would be interesting to do the same test by addressing the vibration attenuation via different frame and fork materials. Same wheelset on a Reynolds 531, Columbus Max / EL OS / SL, Litespeed or Merlin Titanium, Tubed and moncoque carbon frame dujour. Nice video and nice bio positioning too. Thanks!
and while we're at it, let's test it with nice clinchers, cotton open tubulars, and tubulars!
We could really get into it and do the test with nice conventional clinchers with latex tubes, nice cotton open tubulars, and tubulars. Then we can take a real trip and do the test with different types of spokes, spoke counts and rim materials.