Originally Posted by Smorgasbord
I agree that two brakes will probably stop me faster than one. I try to take this into account with my riding - just as you might alter your riding style in rainy conditions. With only a front brake and on a fixed gear I can still stop very quickly, though. I did not mean that this man was wrong, merely that it was an interesting situation. Personally, I think riding fixed with only a front brake and a helmet is safer than riding geared with two brakes and no helmet. I made (and reaffirm) my riding choices based on this opinion. This man seems to think otherwise. I suppose I am wandering into the helmet safety debate somewhat, and I would like to avoid this thread re hashing this overdiscussed topic.
Unless you have poor brakes, the front brake is all you need for the shortest stopping distance. As you apply the front brake, your weight distribution moves forward. With enough front brake applied, the rear wheel will start to lift off the ground. The rear brake does not contribute to braking at that point.
On a freewheel bike, the rear brake is neccessary mainly as a backup to the front brake since a front brake failure would leave you with no brakes at all.