Originally Posted by
Enthusiast
Thousands of urban fixed gear riders can ride effectively in traffic at high speeds with only a rear wheel brake; all it takes is practice and a reckless nature.
and bicycle messengers/fixed gear riders value safety above all else.
Sorry, couldn't resist.
Coaster brakes work but just by virtue of being on the rear wheel they aren't the best choice. It's kind of like using the hand brake to stop a car, -it'll work given enough time and if you aren't going too fast.