higher tyre pressure = slower rolling?

shin0r

In the June issue (225) of MBUK there is a "20 pro tips" section. On page 175 the following passage caught my eye:

"Higher pressures will roll slower (and more uncomfortably) than lower pressures. A general rule of thumb would be to go for 20-30 psi, with lower pressure for larger tyres and higher pressure for smaller tyres".

I was under the impression that higher tyre pressures would roll faster than lower pressures, and the tradeoff is less grip and possibly less comfort. Lower pressures give more grip but roll slower and leave you more susceptable to pinch-flats.

Confused! Could someone shed some light? Is this just a misprint?

Shi

Underscore

From http://www.justridingalong.co.uk/ (regarding going tubeless, but answers your question):

3. Lower rolling resistance.
Rolling resistance is affected by many factors but luckily going tubeless improves them all. The extra suppleness from having no inner tube means the tyre can deform more easily over small bumps, rocks and roots. Less fear of punctures means you can run lower pressures which, you have probably heard, increases rolling resistance but that only applies to roadies. Off road, the majority of rolling resistance comes from bumping over a continuous procession of small divots, rocks, roots, bumps and mammals. Lower pressure means the tyre can deform around the obstacle rather than having to lift the entire weight of the rider and bike over it. It might not sound like a lot but if you are riding over many small bumps several times a second it soon adds up to a lot of energy wasted.

_

RideTheLakes

Yep thats summed it up pretty well above. It's the opposite of what you initially think but it does make sense.

shin0r

Thanks for the info - I think I'll try dropping my pressures a bit this weekend

ChingfordMarin

its like arguing with the other half. your adamant your right and then you read the small print and think "ahhhhhh" damn im wrong! it cant be!

I will also lower the pressures and see how it goes i think

Milkie

That explains why I feel its easier off-road than on-road! I thought it was all in my head!

supersonic

I think it depends on the exact terrain. Drop your tyres to 10psi, see what happens! I wouldn't ride fast hard singletrack with just 20psi.

NikB

I've never ridden below 35psi and usually at 40psi - maybe I need to try a little lower too. Still strikes me as odd that with suspension you need to run what appears to be stupidly low pressures. Having said that F1 tyres run at about 18 psi and they're not exactly slow are they?

RSMarco

Interesting as I ran around 45psi this evening for the first time and it was slow and bumpy, I lowered to 35psi and it felt alot better.

davey1991

in theory it makes no sense. lower presure means more rubber hiting the trail, more rubber down means more resistance, more resistance means speed reduction, but then again gravity decieves us all thanks for the tip goodbye mr solid tyres.

Anonymous

supersonic wrote:

I think it depends on the exact terrain. Drop your tyres to 10psi, see what happens! I wouldn't ride fast hard singletrack with just 20psi.

Curiously, I found out a couple of days ago that I was riding hard singletrack, trails, jumps and drops with 25 and 21PSI front and rear respectively :shock:

supersonic

There is obviously a limit if the theory is true - as in my 10psi example. This limit therefore must change for varying terrain.