Originally Posted by
billridesbikes
@
ofajen Otto, Doesn't the Silca site show this is a real but marginal gain?
Crr is the proportional amount of force needed to move some weight some distance at a constant speed.
Let's take me and my bike together are 80kg (before stopping for chicken fried steak).
The difference between the lowest and highest Crr is about 0.001
0.001 * 80kg * 10m/s*s = .8 kg-m/s*s (N)
Or for me about 9-11s difference over a flat 40km at my FTP.
In a TT that would be a little over an hour for me, yes I want those 11s really badly! But daily riding probably not that noticeable.
It’s not the term for energy loss in the casing you really have to watch out for. As I mentioned, the slope of the surface impedance term above the break point is much steeper, so running too high increases the energy loss at a much greater rate.
Also, that graph is for a surface where the break point is 115 psi for a 700x23 tire. The surface impedances I ride on are a lot more.
Otto