96% of Cyclists Get Their Tyre Pressure Wrong. How To Get It Right

Getting the right tyre pressure is quite a tedious task, but an important one if you want to enjoy your rides! However, many of us take it for granted thinking that it doesn't do much help.

Ollie, on the other hand, is here to tell you that you should think about tyre pressure more carefully with some science to back it up!

00:00 How important is tyre pressure?
00:55 The Silverstone Cycling Efficiency Rig
01:37 What we are going to test
02:46 Testing various tyre pressures on fast Pirelli tyres
03:43 About the special rig
07:06 Dropping the pressure to 5 bar
07:41 Changing the surface of the rig
10:54 Testing the cheap Amazon tyres
13:26 Results from the test
18:13 Looking at tyre width
20:42 Other variables

Useful Links:

Do you normally consider other variables when pumping your tyres?

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[johnnyloco]

If I lost 95 watts I'd be going backwards 🤣

[ldakotatransplant]

After watching this video I decided to put it to the test myself and can with absolute certainty say you are 100% correct! When I adjusted the front tire pressure I gained 5 watts in Zwift!

[insanecomicdude]

My main takeaway here is that, on tarmac, running the wrong pressure is only going to cost me up to about 3 watts, so I don't really need to be too precious with my tire pressure for everyday riding.

Great vid, Ollie!

[joemercs]

This whole exercise revisits the concept of Dunlop. He invented the pneumatic tyre at a time when tyres were solid. The result was a faster and more comfortable ride. Very high pressure pneumatic tyres effectively revert back to behaving like solid tyres. As with any suspension system the principle is to maintain tread contact with the surface being travelled over and this means keeping unsprung weight to a minimum whilst maintaining a well damped but highly compliant travel.

[Stefano-czbo]

As a mechanical engineer, I would welcome a next GCN video with an interview to the designer of this test rig. Some of the questions I would suggest are: 1 - only the rear wheel sits on the drum, whilst in the real case both wheels roll over the road, how do you factor in the resistance from the front wheel? 2 - How do you estimate the power loss? The only viable way I see is to get it as the difference between the power input by the cyclist at the cranks and the resisting power at the drum. However, when we talk of a resistance as small as 20 W, the accuracy of the two powermeters becomes crucial. Ollie: it's not a matter of the sampling frequency (Hz) that matters, it's rather the accuracy of the sensors. If the accuracy is 1% of the range and the range is, say, 2000 W, or maybe even just 1000, it's AT LEAST 10 W uncertainty at each one of the two powermeters, so the total uncertainty is more or less the same as the power loss to be measured, for the good tyre at least. 3 - again assuming the power loss is obtained from the difference between the power input at the cranks and the resistance at the drum, do you remove the effect of the aerodynamic resistance arising from the rotation of the drum?

[kunzworld]

Ollie at his best. Totally geeking out about the test machine and its results. And me? Glued to the screen and just loving it!

[l.d.t.]

17:00 you shouldn't forget that tires at 2 bar tend to drift much more in corners. The testing rig, while very well designed, doesn't take this into account.
And don't forget that while you're not bottoming out on that test rig, pro riders in a peloton, hitting a rock at 55k/hr, will have a much higher chance bottoming out.

[-Demis-]

I'm under a lot of pressure, but I'm still rolling with it! 🚴‍♂️

[rolandmg]

This is a really interesting subject and as an engineer I find the test rig set up fascinating. I agree with lower pressures being more efficient on a rough surface but in a real life situation which includes climbing, sprinting and descending I don't concur. I'm in the Alps presently running Vittoria Corsa 28mm tubulars on Dura Ace 28mm wide rims and set the pressures to the Silca calculator which was 5.4 / 5.25 for my weight 72kg. This is great on the valley roads but climbing out of the saddle was too bouncy and descending and cornering fast around the hairpins was sketchy as the back tyre was slipping. Yesterday I increased the pressure to my normal 6.2 / 5.8 and the bike felt like it was on rails cornering and climbing felt so much more efficient. I know it's difficult to replicate these conditions on the rig but the results are a good starting point but everyone should tweak them for the terrain and conditions.

[vomaximus]

To my knowledge, Pogačar routinely rode 30mm Conti tyres on fat, tall Enve aero rims for this year's Tour win. Although his body weight is very low which makes that counter-intuitive, of course his average speed is a lot higher, plus the aero gains when he attacks off the front become far more significant with that combination.
Re: your comments about best tyre pressures on cobbles Olly, don't forget that most of Paris-Roubaix is ridden on tarmac or concrete slab, so the tyre pressures the Pros ride are necessarily a compromise between the rolling resistance on all those surfaces.
Finally, of course we all wince at the thought of 70s Pros riding 23mm tyres in the very same race, but then they rode skinny, very shallow aluminium sprint rims for tubs, and there'd have been a lot of deflection and shock absorption going on within those rims, plus much looser spoking, also the forgiving steel frames and forks of the time. But for sure, the ride would have been harsher.
Nice piece though Olly, fellow Physics nerd here!

[kidShibuya]

Might want to change the title. I thought this was a clickbait type video with nothing useful, but I watched when I saw the runtime and I am glad I did, always love good testing.

[gtmedley]

Excellent tech video. I proves what I always have believed, the more you get into bike racing, the more it turns into car racing. Silverstone, even!

[richardclinker]

I dropped my pressures to 4.5 bar front, 5 bar rear 28mm and did a ride past Silverstone. For me, no faster but felt a lot nicer, easier. By the way. Have also been experimenting with a thin layer of talc between butyl inner tube and tyre casing to see if that reduces internally induced rolling resistance. I think it might do...

[tonym]

Great video. Just to add, on Arenberg alone the system takes approximately 23000 hits (2300m x 5 cobbles/m x 2 wheels). Within those 23000, it's the random missing or proud cobles and wide gaps that are the problem.

[Andy_ATB]

Plenty of bike shops have been guilty of this as well. I recall buying a few bikes, and them pumping the tyres up to over 100psi - despite me asking them not to. Got home and let the tyres down to a proper pressure.

[mpvsystems]

This rig looks ideal for comparing the performance of an old school tubular with a TLR. For example, the Pirelli P-Zero is readily available in both formats in size 700 x 28. I would expect the casing material and layup to be identical too. Of course the big difference is that the tubular will have 30% more usable casing making it much more compliant and comfortable at any given pressure not to mention almost impossible to pinch flat. Also, one would expect the tubular to handle a much wider range of pressure especially on the low end owing to the flangeless rim profile.

[JanGoh-jbge]

I'd like to see more about tubeless tyres and inserts and how they affect handling and puncture resistance. The drift that I get on my tyres with a foam insert is very much like the feeling I got with high-quality CX tubulars. There's a drift, but it's controllable. You don't want that on the road necessarily, but it feels good on gravel bikes. But I think there's a lot to be done there. High quality TPU tubes are nice I guess, but they're still a tube and I feel like that has very specific drawbacks that most riders and unsupported racers shouldn't have to contend with.

[abirkhanrafee]

gcn should keep doing videos like these <3

[dudleyarnold]

Possibly the best cycle science video I have seen. Vindicates my view that a lot a cyclists inflate their tyres to high. 65 to 80 psi is a good median for most terrain.

[cyclingcomputer]

In other words, on tarmac: it will depends of the type of tyre, rider weights, and pressure to get more or less 3 watts. I'll continue use my 80 psi (between 6 and 5 bar) and it will not going to affect my super 195-205w on average rides.