One brake Single-Speed fools

Im not saying its a good idea, but was reading a bit of sheldon the other day and he writes that the back brake is pretty much redundant in terms of stopping force with a distance 2x that of the front brake. the front is at optimum stopping power when the back wheel is at the point of almost lifting off the ground with minimal traction. The back brake comes in to effect as a stopping force for times when it would induce a front wheel skid such as wet or icey conditions. mainly as you cant recover from front skids. so i suppose for the fair weather cyclist the only front brake option could be argued as sufficient. Also raises the no brake fixed question as most argue the front brake serves as use in the wet or times when rear wheel skid traction is low... im not ready to ditch mine, but its interesting that even in the dry you are accepting the fact that your brake distance is at least double from not riding a front brake.

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

Using a rear brake only is almost pointless. Unless I'm going downhill, in which case it is a lot easier for the rear to lift of the ground, I only ever use my front brake. Modern caliper brakes are powerful enough to cause a skidding stop using just 1 brake.

Skilled cyclists use the front brake alone probably 95% of the time

Many cyclists shy away from using the front brake, due to fear of flying over the handlebars. This does happen, but mainly to people who have not learned to modulate the front brake.

If you're stupid enough to use a short pull brake (dual pivot caliper) with a long pull lever (almost all MTB style levers) then you may have this problem.

http://sheldonbrown.com/gloss_bo-z.html#brakelever

Paradoxically, the lever will feel very solid, the brake will engage with a very short amount of lever travel...but won't actually be squeezing very hard on the rim.

Your stopping power should be limited to how much grip your tyres have on the road. A single front OR rear brake should be good enough for this, on 700c wheels, which have an extraordinary amount of pressure on the road surface due to their low surface area.