Gear ratios for no brakes riding...

Maximum Deceleration--Panic Stops

The fastest that you can stop any bike of normal wheelbase is to apply the front brake so hard that the rear wheel is just about to lift off the ground. In this situation, the rear brake cannot contribute to stopping power, since it has no traction.

http://www.sheldonbrown.com/brakturn.html

it seems to me that brakeless riders are unwilling to concede that it is more dangerous, that they would be safer with a front brake, but that they do it anyway