In reply to rocksol:
Helmets are a very good idea, I wear one all the time.
Making them compulsory is a very bad idea. In the places where it has been implemented, (NZ and parts of Aus), there has been a dramatic decline in the numbers of cyclists. And given the health benefits of cycling - both to the cyclist and society as a whole - this far outweighs the number of cyclists dying of head injuries.
Plus you are tackling the problem from the wrong angle - it's like tackling knife crime by making anti-stab vest compulsory.