As soon as you pump a tyre above a certain point it falls off a cliff effectively in terms of efficiency. Reason being the bike and the rider has to absorb that energy rather than deflection in the tyre. To know what that point is you need to factor in what the tyre measures out to on the rim, road surface, total weight (rider + bike), also the speed at which the bike will be travelling. Much better off being a bar under optimum than a bar over. For my TT setup with me at 70kg for the surfaces I ride on about 67 - 70psi is the fastest setup. Changing tyres tubes and running them at optimum pressures has saved me circa 20w+ @ 45kph.
Hope you don't mind if I probe some of this, Huw. Some reputable links to reinforce your answers would be great.
As soon as you pump a tyre above a certain point it falls off a cliff effectively in terms of efficiency.
You're making this up, depending what you mean by 'falling of a cliff' 'effectively' and 'efficiency'. Beyond a certain pressure a tyre's rolling resistance plateaus. Have you a graph to share?
"As pressures increase, tires roll faster, but the performance levels off at a certain pressure. Beyond this point, higher inflation brings only negligible performance improvements." [ Heine, J. and M. Vande Kamp, 2006: The Performance of Tires. BQ Vol. 5, No. 1, p. 1. ]
the bike and the rider has to absorb that energy rather than deflection in the tyre.
You've not mentioned this 'energy' before (but I understand the 'suspension (body) losses' idea you tried to share).
To know what that point [optimum pressure] is you need to factor in what the tyre measures out to on the rim, road surface, total weight (rider + bike), also the speed at which the bike will be travelling.
And the formula is? Actual tyre width: check. What metric can you use for road surface? Load on each tyre (NB different front and rear): check. How much do each of those factors separately contribute, or are you making this up?
Much better off being a bar under optimum than a bar over.
Why? More likely to get snake bites, so better to be over than under.
For my TT setup with me at 70kg for the surfaces I ride on about 67 - 70psi is the fastest setup.
How do you know? Both wheels? 32mm wide tyres! On a TT bike? Do your competitors buy in to this outlying philosophy?
Changing tyres tubes and running them at optimum pressures has saved me circa 20w+ @ 45kph.
What were the previous tyres, tubes and what were the new ones? I bet that will account for any power saving that you purport to measure. If you were running previous tyres at (too) low pressures then running the new (better) ones at optimum (15% drop) pressure would obviously offer rolling resistance reductions.