Originally Posted by Maelochs

Energy transfer with a bicycle is pretty simple---the rotating crank transfers energy to the rear wheel and to the ground to propel the bike forward. Any motion which is not in the direction of rotation is not moving the bike forward.

If the shaft of the golf club is not sufficiently rigid, it will flex back from the ball at the moment of impact, wasting energy---imagine a golf club with a thick stiff rope shaft ... not quite going to get those 275-yard drives. If the bottom bracket of a bike flexes side to side, the amount of energy it absorbs---the amount of energy needed to make it bend---is Not getting through the crank arms to the chainring to the chain to the cassette to the ground to propel the bike forward.

Think of it this way---would you wear loose, soft-soled shoes with big thick cushions on the sole when biking? Why not? Because compressing all that cushion and flexing the sole would waste energy---not magically "return energy to the system." The enrgy needed to fully compress all that adding would not drive the bike. The energy absorbed by the bending of the sole would not drive the bike.

Which is why cycling shoes have super-rigid soles ... energy transfer is maximized when flex is minimized.

If you can explain precisely how there is a "trampoline effect" in the bottom bracket of a bicycle frame and how this helps move the bike forward ... I will have learned something. But do consider---- a golf club striking a ball is a direct impact, and the compression and subsequent expansion of the ball is used as a spring to increase distance.

There is no spring in a bicycle's drive train---as with stiff-soled shoes and stiff cranks and a chain which hopefully doesn't stretch, there is no spring. there is no one-time impact, no controlled compression and expansion is response to that impact. The only "impact" as such is the pressure of the feet on the pedals, and there the impact should be continuous force, not a sudden impact.

If there is any compression, it would involve the foot, ankle, and leg---and the idea there is for the foot, ankle and knee to be pushing through the stroke, not springing back ... when your feet, ankles and knees can no longer stop from compressing, when you can no longer extend them to pedal, you have hit max power. The golf ball is supposed to compress and expand---your legs are not supposed to go backwards from the force of pedaling.

Again, consider a very flexy golf club shaft---it might whip on the downswing and snap forward, but if it flexed Backwards or sideways upon impact, you would redesign the club. That would be lost energy.