Many folks believe that wearing a bike helmet is a panacea to all possible injuries. Actually, they aren't. They're not designed to help you much if you get smacked head-on by an SUV or run over by a bus, but they'll at least help mitigate brain injury if worn, and worn properly. A couple of years ago there was an article concerning a student who fell in traffic and had his head run over by a deleivery truck. His helmet did its job and prevented the guy's head from being squashed like a melon... but this is a pretty extreme case.

A helmet is part of one layer or component in a multi-faceted approach to crash prevention/accident avoidance. Consider it as a partial hardware solution to a software problem. You can prevent more than 90% of the situations that lead to your really wishing you had worn your helmet on this ride... by taking the software solution:

1. Control your bike so that you don't fall off, or collide with other solid objects.
2. Follow the rules. Obey all traffic signs and signals, and don't be the cause of a colision due to your erratic riding.
3. Discourage the mistakes of others by positioning yourself in the roadway where drivers expect to see other traffic, and ride predictably and alertly.
4. Avoid getting caught up in the calamity when others eventually make mistakes by using bike handling/avoidance manuevers to get out of a crash situation.
5. When all the above fail, survive the crash by using protective gear -- a properly worn helmet, gloves, etc. ... think of them as sort of like your seat belt in a car.

Tom