Originally Posted by
cyccommute
Freezing rain will coat the rotors of a disc brake just as well as it coats the rims. Ice on rotors would have the same effect as ice on rims...poor braking. And braking on ice isn't limited by the brake power but by tire cohesion. I would want less powerful brakes with a whole lot of modulation on ice to avoid locking the front wheel. A disc, particularly a hydraulic disc, isn't going to make stopping on ice any easier.
Well, sorta. There's less water splashing onto the hub in the center than on the rim. And though there is ice on the rotor, it strips off instantly (well, in a single revolution) when I squeeze the brake, because the disc brake pad edge is sharp and hard. I've watched it happen, when I squeeze the brake, the ice just flies off and the brakes begin working within a second. On the rim brakes I once had to dump into a snowbank and do a sort of half jumping Fred Flintstone stop after the brakes completely failed to do anything for many yards on the way down a hill.