I was always wondering this. Imagine a steep descent. What is better for brake wear - braking constantly or more powerful just at the end?
Anybody knows? Goes for both rim and disc brakes
Physics says both use the same amount, just one is spread out more and the other is all at once. I don't have the formula, but basically it takes the same overall effort to stop an object regardless of if it's slowly or very fast.
If you however travel at greater speeds, you loose more energy to air resistance since it squares with velocity. If you only brake at the end you will have lost a greater amount of energy to air resistance and less energy will go into the brakes.
I get the thinking (because it's my first thought too), but the basic force formula (F=M*V^2), means velocity is the greatest influence on Force.
So braking from the higher speed will result in a greater force, meaning more energy dissipation.
I think. Maybe there's something I'm missing here, like including the time to convert that energy to heat via the brakes. Perhaps in the end it's all the same (braking early and keeping speed down), since we're always converting the energy imparted by gravity to heat.