Tyre Pressure - 25mm

[bpsmith]

Thanks for the replies guys!

That last link, in addition to others above, is what I found a few days back and made me think about posting. Some of the rpessures quoted seem very low indeed, but I am keen to take advice and will start with a trial of maybe 75 on front and 90 on back first maybe. How does that sound?

Do you guys notice any difference in speed with lower pressures, or is it just a comfort gain for no speed loss?

 

[John the Monkey]

Do you guys notice any difference in speed with lower pressures, or is it just a comfort gain for no speed loss?

Personally, I think a lot depends on the tyre - I've had some that are finicky, and feel dreadful if the pressure isn't just right, and others that will roll fine, even 20 psi off the usual pressure.

In general, I think stiffer carcassed, more heavily puncture protected tyres fall into the former category, and more supple tyres into the latter.

It's also worth mentioning that that's "feel" - I couldn't say for sure that speed was actually affected.

 

[Accy cyclist]

I find Continental's recommended pressures are usually about right - the say 110psi for 25c GP 4000;

http://www.conti-tyres.co.uk/conticycle/ti grand prix 4000S.shtml

Seems high to me (last 25c I ran were Pro Race2, at 90psi) but I'd start there and experiment (fwiw, the old Michelin charts reckon 93psi for your wieght on a 25c tyre).

See also;
http://www.dorkypantsr.us/bike-tire-pressure-calculator.html

I've used the chart and according to it,my front tyre should be 73 psi and the rear 114 psi. I'm going to give this a go and see how it feels.

 

[shouldbeinbed]

I've generally stuck to 100 front and rear on 23's & don't see a lot of loss over a week or so. I irrationally worry about the tyre rolling about on the rim in corners with lower pressure in, but I'm sure the load particularly on the front wouldn't be enough to cause such an imagined failure even with a much softer setting.

 

[John the Monkey]

I've used the chart and according to it,my front tyre should be 73 psi and the rear 114 psi. I'm going to give this a go and see how it feels.

I've never ridden with so much of a diference (10 psi less in the front is as much as I've tried) but then the old chart just gave a recommended pressure, not a front/back pressure.

I'd bear in mind the comments about tyres too in my earlier post - subjective, I know, but some really do feel godawful if the pressure's not right.

 

[bpsmith]

Did a quick test ride tonight. Dropped to 85psi front and 105 psi rear over 30 and a bit miles...and it felt more comfortable and grippier at times...but was far too low for my liking. Really went for it and was a lot slower than previous times when it was windier and I gave it less effort. It's trial and error, I know, but the recommended pressure is even lower than that. Certainly doesn't suit my riding it appears. Going up to 100psi front and 110psi rear next and will try the same route probably.

 

[boydj]

Interesting info here - http://velonews.competitor.com/2012...-pressures-were-roubaix-riders-running_212925 - on tyre pressures used by pros on the Paris-Roubaix. Lower for the cobbles than they would use on good road surfaces, but it would suggest that <100 psi is not going to hurt road performance on a 25mm tyre.

 

[bpsmith]

They are mostly using 27mm or 28mm tyres, which result in a lower required pressure anyway. The pressures they used are similar to mine tonight and would have been higher with a 25mm naturally.

And they are PRO's! Let's see how many of them use those pressure on the Tarmac in the TdF come the weekend...

Interesting article nonetheless.

 

[bpsmith]

110psi front and back...so much better!

There might be a happy medium, so won't add air on next ride and see what happens.

 

[Accy cyclist]

Well i've been trying 85(ish)front and 115(ish)rear. I can't say there's any difference between that and 100 to 110 front and rear.

 

[Doyleyburger]

Going to keep an eye on this thread.

Been running my new 25 tyres at 100psi for both the front and rear. Perhaps I should drop the front slightly. Used to run my 23's on 110 and iv instantly noticed the difference...... Faster rolling for sure, and much more comfy ride with a lower pressure