morganism
SunkCostFallacy
on bike tires, but interesting
blog.silca.cc
"'How low are you willing to go?' The risks here are highly asymmetric, 3psi too high, and you may not be as fast as your rival, yet 1psi too low and you may be standing on the side of the road waiting for 2 spare wheels while the race rides away from you!
Similarly, we find another Icarus asymmetry in road and track racing at much higher pressures. This is analogous to Icarus flying too close to the sun! While we were all brought up to believe that higher pressures are better on road and track, testing has shown this not to be the case. Rolling resistance will decrease as pressure increases, but eventually, the pressures become high enough that the tire begins to ride 'over' the bumps rather than 'through' the bumps and while the deflection of a tire casing is more than 90% efficient, the lifting and dropping of a bike and rider over each of those thousands of bumps is more like 30-40% efficient..So just as we see in the cobble analogy, even decent pavement can become problematic as pressures become too high!
In this case, the asymmetry is opposite that of the cobble story. The rolling resistance on pavement decreases as pressure increases, slowly and steadily.. 60psi is OK, 70psi is better, 80psi is better still, 90 is really good and suddenly 100psi is .. wait? worse? Yes. Now the penalty, in this case, isn't standing on the side of the road with broken equipment, but the hockey stick is working against us! Our testing shows that while 5psi below optimal pressure for a given surface may cost you 1 watt, 5psi above the optimal pressure may cost you 3-4 watts.
Asymmetric Effects of Tire Pressure Optimization
A look at the asymmetric performance effects of tire pressure on different road surfaces plus some stories about product development and racing Paris Roubaix
blog.silca.cc
"'How low are you willing to go?' The risks here are highly asymmetric, 3psi too high, and you may not be as fast as your rival, yet 1psi too low and you may be standing on the side of the road waiting for 2 spare wheels while the race rides away from you!
Similarly, we find another Icarus asymmetry in road and track racing at much higher pressures. This is analogous to Icarus flying too close to the sun! While we were all brought up to believe that higher pressures are better on road and track, testing has shown this not to be the case. Rolling resistance will decrease as pressure increases, but eventually, the pressures become high enough that the tire begins to ride 'over' the bumps rather than 'through' the bumps and while the deflection of a tire casing is more than 90% efficient, the lifting and dropping of a bike and rider over each of those thousands of bumps is more like 30-40% efficient..So just as we see in the cobble analogy, even decent pavement can become problematic as pressures become too high!
In this case, the asymmetry is opposite that of the cobble story. The rolling resistance on pavement decreases as pressure increases, slowly and steadily.. 60psi is OK, 70psi is better, 80psi is better still, 90 is really good and suddenly 100psi is .. wait? worse? Yes. Now the penalty, in this case, isn't standing on the side of the road with broken equipment, but the hockey stick is working against us! Our testing shows that while 5psi below optimal pressure for a given surface may cost you 1 watt, 5psi above the optimal pressure may cost you 3-4 watts.
