Quote:
Originally Posted by Jan Heine
On real roads, higher pressures don’t make tires faster, because the greater hysteretic losses (the tire deforms more) are countered by the lower suspension losses (the bike vibrates less). This is now widely accepted – it’s been shown in test after test, not just by Bicycle Quarterly, but also by Joshua Poertner and others.
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According to Anhalt and Poertner, roller tests correlate very strongly with real-world tests, up until the breakpoint where suspension losses overcome. That breakpoint is actually really pretty high -- ~110psi for the 25mm GP 4000s II and Vittoria Open Corsa. Even for "course intermediate asphalt", it is still quite high at 100psi (which is even above 15% drop = ~88psi according to your chart).
https://silca.cc/blogs/journal/part-...-and-impedance
http://www.slowtwitch.com/Tech/What_...ube__1034.html
Have you commented on Tom's breakpoint theory yet?
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Also, the 25mm GP 4000S II has a near-identical sidewall and tread thickness to the Bon Jon Pass, yet for the same 15% tire drop (100lb load: ~88psi for GP and ~50psi for Bon Jon) it seems the GP is ahead by a huge ~7-8 watts. Is this to say Compass tires could be much faster from a more advanced rubber compound (as discussed a few posts above)? Similarly, what would you expect if bicyclerollingresistance tested the Cayuse Pass?