Originally Posted by Joe Schmoe
Agree with patentcad. I love to have disk brakes on my road bike for that reason. They can really make the difference on a descent. One of the bike trails I ride has a steep descent (getting up to 45 mph is no problem) that ends in an almost 90-degree turn to the right. If you keep going straight you hit a fence and fall into a concrete drainage basin (if the fence doesn't stop you). On this descent, you simply have to slow down about half the way through. I would love to push it a little farther, but rim brakes just don't provide the stopping power. This same descent is much easier on my MTB.
Also, sometimes disk brakes are a real advantage in automobile traffic. Even if you are careful, sometimes the others on the road with you are stupid. The extra stopping power of fisk brakes could wasily prevent you from doing an endo over a car.
For those who have not ridden disk brakes, they are REALLY powerful, especially the hydraulic kind. I have never measured, but I am sure that a stop from 25 mph can be accomplished in @10-15 ft. The most dangerous part is modulating your stop so you don't go over the bars -- they are that powerful.
The same descent is much easier on your mtb because you aren't going as fast. I'd say that your mtb brakes feel more effective because you have more surface area contacting the road.
Fact: Stopping distance is more a factor of tire to road than brakes...especially in the wet. Disc brakes are no more effective in the wet than rim brakes on a skinny road tire. You might as well argue about the virtues of fat mtb tires on a road bike. You'll be barking up the same stupid tree. Good luck with that.
I'm sure my Dura-Ace rim brakes could send me over the handlebars if I were stupid enough to apply the force necessary to send me into such a ridiculous position. Your point is moot.