Velorution brings up the old argument about the statistical unimportance of bicycle helmets. Long a discussion topic on
rec.bicycles, the non-intuitive suggestion rests on the idea that bicyclists that do not choose to wear helmets (yet get good exercise) probably live actuarially much more healthy lives than those who would rather not bike because of the helmet fear factor.
The fear factor is basically divided into fear of looking like a dork and fear of potential dangers while riding a bike. If you have to wear a helmet, it must be dangerous, right?
To most, helmet-wearing bicyclists poking around at a few miles an hour is nothing out of the ordinary. But if you think about it for a second, wouldn't you think it odd to see a pedestrian wearing a helmet? In reality, the pedestrian holds his head higher above the ground than a biker does, so would suffer greater head injuries should he/she keel over. I still believe that to a large segment of the population, helmets and fashion do not mix, which influences these people to stay away from bicycles.
By the way, I do not wear a helmet, and would do so only if required for a race.