Originally Posted by
cxwrench
Where does the energy go? Does the frame flex and stay in that position? No, it flexes back. Does the frame get hot? No. Pretty much all the energy that causes the frame to flex is returned.
Even if all the energy that goes into flexing the frame is returned, it may not be returned in a way that propels the bike forward. You have to look at the whole system and where the losses are.