my fixed has a front brake only. it stops as fast as my geared road bike that has front and rear brakes. most stopping force is on the front wheel because of the weight being thrown forward as you slow down. i recommend having a brake, if you break your chain its the only way you can stop. i've broken a chain before. not to mention if you are hit by a car and don't have a brake you're likely to lose any lawsuit that comes from that collision because it is illegal to ride without a brake, even on a fixed gear. you can still skid around all you want and not use the brake except for emergencies if that's what you want to do.