Originally Posted by
elTwitcho
Not just the fixed gear thing, but physics as someone mentioned. In the vast vast majority of situations, a front brake is the only brake you need/should be using as it's more effective than back brakeing by a good margin. Using both brakes at once is not advised by some people as it can lead to fishtailing.
That's right, i pretty much used only front brake even on my geared bike. However it's a good idea to have two, but you'll most likely be fine with just a front. I have never had a brake fail on me ever so far, so it has to be a rare occurrence. And even if it happens, you can use your leg on the back tire to stop.