Tyre pressures in long distance events

[Ajax Bay]

Thank you for that historic insight to track cycling though a simple answer to any of my questions would have been attractive and to your credit. And on the road your tyre width on your TT bike is 32mm then? Which would fit fine with your avowed 70psi rear, but @ 45kph would result in expending an unattractive amount of energy overcoming the increased drag.
I thought you'd appreciate re-reading some of your posts from yesteryear:

I don't generally believe most things I read with regard to improving cycling performance etc, as it's usually to try and sell something.

Although I guess wider tyres at lower pressures is not really a useful 'selling' point: air is free.

 

[Ajax Bay]

And this, with regard to being able to determine what the optimum pressure in your TT bike tyres is:

It'll be very difficult to accurately measure a wheels performance. For example, say if you rode a set route at a set power and recorded a time. Even if you were to go back and do exactly the same on a different wheelset it would be almost impossible to compare accurately due to small changes in wind speed/direction, slight difference in tyre pressure, not riding over the exact same piece of tarmac etc... All these little things would make a difference and make any test not very accurate!

 

[huwsparky]

And this, with regard to being able to determine what the optimum pressure in your TT bike tyres is:

Optimum pressure is optimum pressure. The only difference with it being a TT bike front and rear will be the same as weight distribution is 50-50. Obviously I'm a lot more fussy with what pressure I run in that case as it matters.

 

[cougie uk]

So there was enough left to resist pinch punctures by the end. We had a track pump on the coach to London.

Latex tubes can lose half the air in 24 hours. They are sometimes worth it, though.

What tyres are they ? Have you checked the Max pressure for the tyre (and the rim for that matter)

I'm finding things much better with lower pressures than I used to put in - on the advice of a Continental tyre mechanic. Very few incidents.

 

[Ajax Bay]

Optimum pressure is optimum pressure.

How can anyone disagree with that?

 

[huwsparky]

This calculator is going to be the most comprehensive there is. Try it out. You HAVE to know what your tyre measures out to on the rim though. I race on 23mm but they measure out to over 26mm on the rims I use.
https://info.silca.cc/silca-professional-pressure-calculator

 

[huwsparky]

@Ajax Bay they guy who who developed this is a guy called Josh Poertner. Well worth listening to what he has to say with regards to pressures and generally saving a few watts here and there which I appreciate 99% of people who cycle won't really care about.

I can actually validate my savings but I can't go into it here, it will likely break me. But i can assure you I've saved around 20w @27mph, i appreciate people don't generally ride at 27mph but there's a lot of little savings to be made for everyone, many of them for little outlay.

 

[Ajax Bay]

Rolling-resistance-and-impedance

Green is 'brand new asphalt, yellow = coarse intermediate asphalt, and red = machine roughened concrete (simulated cobbles)

 

[huwsparky]

You see what i mean by tyres effectively falling off a cliff beyond a certain point? We have hardly any smooth roads where i live, it's all chip and seal which as we all know when you transition to one from another travelling at the same speed gets either very easy or very hard depending on which way you're transitioning.

 

[matticus]

slight thread diversion ... do you really live in Llangrannog?? What a delightful (and tiny) place to live! I don't recall the roads between there and LLandysul being too bad. Perhaps bad for Wales, but that means better than almost all of England

 

[huwsparky]

slight thread diversion ... do you really live in Llangrannog?? What a delightful (and tiny) place to live! I don't recall the roads between there and LLandysul being too bad. Perhaps bad for Wales, but that means better than almost all of England

Yes, just outside, we're very lucky really. We get enough climbing in down here!! Surfaces are mostly chip and seal, there's stretches of better surface but generally i don't really ride it due to traffic, especially this time of year.

 

[Ajax Bay]

Thank you. My daughter will be riding the National 100 miles for Royal Wootton Bassett in a fortnight. Her wheels are
Vittoria Corsa Speed G+ 2.0 (TLR), 25mm wide (measured) and weighing 70kg (bike, rider and hydration) she'll be riding them at 85psi, aiming for as close as she can manage to 4 hours.

 

[huwsparky]

Thank you. My daughter will be riding the National 100 miles for Royal Wootton Bassett in a fortnight. Her wheels are
Vittoria Corsa Speed G+ 2.0 (TLR), 25mm wide (measured) and weighing 70kg (bike, rider and hydration) she'll be riding them at 85psi, aiming for as close as she can manage to 4 hours.

Definitely the best tyre for the job. With latex tubes or tubeless? Good luck!

 

[Ajax Bay]

Tubeless - team supplied. Think her last long (100+) trial was using 5000s and latex, but she's had these/the bike/the wheels since January.