To gutkrencher: a singlespeed has a freehub that can go wrong. Futhermore a SS does need brakes, so pads and also replacement cables are needed. A fixed gear is so much more simplistic, a blast to ride and not to mention how much leg strength you build when training with one, because you don't have any chance to rest even when braking. Besides fixed gears and singlespeed look so much alike that you will end up looking like you are taking part in a bread advert of sorts :P