Originally Posted by
Alan_F
I haven't been in a science classroom in a very long time, but your second point doesn't make sense to me. Regardless of the mechanical advantage, a brake converts kinetic energy to heat energy. The only way the mechanical advantage could generate less heat in the pads/rotors during braking is if it sent the energy somewhere else in the system compared to a brake with less mechanical advantage. Am I missing something?
The leverage of a larger rotor means less energy. Remember, Archimedes said "If I had a lever long enough, I could lift the earth." In other words and for experiment's sake, if you had a REALLY large rotor (much larger than your wheel), you could easily stop your wheel with your fingers. Again, if the rotor were large enough. So a larger rotor will require less energy to stop. At least that's my interpretation! (Granted 20mm difference isn't much, but it's still something. That combined with additional surface area makes a difference.)