Which is supposed to have a stiffer BB? The P3 or the P3 carbon? Thanks for replies in advance…
P3C. Quite significantly, I believe.
If you’re seriously worried about the stiffness of the P3 bottom bracket you shouldn’t be wasting your time on the slowtwitch board. You should be racing in France now. 
To me, and this is utterly unscientific in every way, I like the P3SL better.
If you’re seriously worried about the stiffness of the P3 bottom bracket you shouldn’t be wasting your time on the slowtwitch board. You should be racing in France now.
Or the world track championship…
Given that the standatd P3 is stiffer in the BB than a Cannondale according to Tour Magazine, I think you needn’t worry. But the P3C is about 5% stiffer in the bb than the P3 SL.