Larger Rotor Brakes

ocdart said
Some good answers above, but the real increase in braking efficiency is due to the greater 'swept area' of the larger rotor. Because of the increase in diameter, the pad is in contact with more area (square inches of contact) of the rotor per revolution of the wheel. The larger the diameter of the rotor, the more area the pad will contact during a single revolution of the rotor. Therefore, more 'swept area'.

This is very true but only if we are comparing rotors with the same coefficient of friction... hence if you are very rich you could buy a small carbon ceramic rotor and have enormous braking force while keeping rotation mass to a minimum! But that is only if you are very rich!