Originally Posted by cyccommute
Sorry but I don't agree. A rotor brake doesn't stop me and my bike in half the distance of a V-brake (or even a canti). There might be a slight advantage but discs have twice the brake power of rims?? If you do an honest test, I doubt that you will find a modern linear brake that would need, for example, 50 feet to stop a bike while a disc could do it in 25 feet. Show me some data and I'll eat my words but discs just aren't twice as good as rims.
And don't forget to mention that a rim brake IS a disc brake - with a 26" diameter disc. I don't know much about mountain bike parts, but the really fancy high-end super powerful DH disc setups all use larger discs, right?
Hydraulic systems and discs have certain advantages over rim brakes, but power is not one of them - it's dependent on the size of the rim (or disc) to pad contact area and the amount of distance the pads move for any given amount of hand movement. Road racers use caliper brakes to slow down from extremely high speeds, and have for probably a century.
Disc brakes are definitely cooler, though. And anybody who says they're only interested in functionality is probably named Sheldon Brown.