one more scenario that might help....Say I maintain my current leg strength but I weigh 140 lbs....I go up against McEwen who we've been saying is 140 lbs.....why is he still faster then me? Because his leg strength (down force) is greater than mine...which contributes to a larger moment at the pedal leading to an increased angular acelleration of the crank arm which causes a faster spinning of the chain and thus a faster rear wheel which leads to a great speed.