I have a bad wing, so Ive been on my rollers with a fork stand. It's Fredilicious, but better than no riding. Anyway....

With the fork held solid the frame flexes under you as you pedal, as we all know. The deflection appears to be primarily in the front triangle. As the frame flexes, it tilts the rear wheel slightly side to side. As this happens, the rear steers about an inch or 2 side to side. So when riding normally down the road this must be happening to some extent, which would contribute to tire scrub.

I've always said that frame stiffness doesn't affect efficiency. I'll still say that the frame itself is not 'absorbing' (I don't know what that means, honestly) power. I will say that this deflection may very well effect tire scrub which would affect overall efficiency.

Any thoughts?