Does Higher Tyre Pressure = Faster

Bloz

I have always run my Schwalbe Ultremo's at around 120 psi but just noticed the casing say they can be recommended up to 145 psi - assuming they don't go bang at that pressure would you expect that to make any discernible difference in speed ? At 125 psi they are already pretty firm and don't flatten out much when I get on the bike.

jibberjim

No it doesn't, depending on your weight and the road surface they may already be too heavy - you'd have to be quite a big guy on smooth surfaces.

On extremely smooth surfaces the less deflection in the tyre the better so higher is better, but on normal road surfaces deflection in the tyre acts to stop bouncing and makes you faster.

drlodge

I tend to run my 23c tyres at around 110psi, but am tending to lower the pressure in the front tyre to reduce vibration and soak up the bumps a little. You may find pumping the tyres up to 140 makes them so hard they loose their vibration absorbing properties, so its like running on solid tyres. And if the tyre is skipping over the surface it probably won't be any faster.

Giant Phil

The easy answer is yes. If the tyres are at a higher pressure there will be less contact area with the road, less contact means less friction, less friction means you go that bit quicker. In practice the high pressure will lead to a harsh ride and you might find your muscles fatiguing due to the vibrations, for TTs this effect is negligible but for anything over 25, comfort is king and ~100 psi will do you fine.

I run Lithion2s at 110 on the back and 90ish front for longer rides

Hoopdriver

Actually higher pressures are of use only on smooth velodrome surfaces. On the road the high pressure, anything over 110, are counterproductive since the rough surface will negate any improvements in rolling resistence.

Monty Dog

Higher pressures = more punctures + discomfort which both make you slower in the long run. FWIW energy losses due to friction aren't as significant as hysteresis i.e. due to deflection of the tyre carcass, which are greater for a rougher road surface. Tyre manufacturers suggest >110psi = no benefit, the exception being on a smooth track

mamba80

Interesting - a guy down here who was an elite, div champ and uk masters winner - ran his tubs at 120psi frt and rear.
And a mechanic for a Maratona "amateur" team told me 120psi for Conti Comps and 140psi for Vitt Corsa cx.
Of course these are for tubular tires with their softer sidewalls.

For any clincher, ive found anything over 110psi gives numb hands and eventually numb feet - with 95 to 105 being perfect for any tire.

Monty Dog

...and a pro team mechanic told me of the stories of UK pros who used to ride in Flanders and were constantly plagued by DNFs due to punctures whereas the local riders didn't (because they didn't pump their tubs to 10 bar).

Bloz

Interesting stuff - thanks guys