cyclistgo wrote:
I understand RChung, that the best option is not try to calculate Crr on velodrome, is get data from roller test, or from data tables from https://www.bicyclerollingresistance.com/road-bike-reviews? If I decide to get data from other experiments, how should I convert or adjust this factor of Crr to my test? For temperature?
I´ve been reading about aerodynamic very different things...
No, I'm not sure that's the *best* option. Crr differs across velodromes, so whether that's the best option depends on if you can get away with transferring Crr values from another testing situation, and that depends on how precise you need to be.
The purpose of models isn't to fit data, but the test of a model is. If you think that Crr (and CdA) vary with speed, the thing to do is to test it. Our current model of drag forces (slightly simplified to get rid of the potential and kinetic energy terms and assuming no wind) looks like
Watts = Crr * m* g * v + 0.5 * rho* CdA * v^3
or
Force = Crr * m * g + 0.5 * rho * CdA * v^2
So the test to determine dependence of Crr on speed is to estimate the coefficients of a model that looks like
Force = A + B*m*g*v + C* v^2
and see whether the coefficient B is different from zero. The problem is that you also think that C is speed dependent, so interpreting B may be hard -- but at least you'd know if dependence was an issue. You might also be able to vary m to separately estimate a Crr dependence and a CdA dependence, but I have to think on that a bit more.