It seems that while helmets do save lives, they aren't very efficient at it.
A new helmet law reduces bicycle deaths among the affected age group by about 19%. It doesn't affect older riders. Since serious bicycle accidents are rare, however, the absolute numbers are still small, about eight fewer deaths a year among kids 5 to 15 than would otherwise occur in the states with helmet laws. "It's not a ton of lives when you compare it to something like wearing your seat belt," says Prof. Stehr.The affected age group is kids under 15. She also doesn't say if the reduction is overall or per state. Either way it's not a very big number. In any case helmets reduce death and injury in another, probably unintended way: They take a big bite out of the numbers of kids who actually ride bikes.
One reason for the drop is, of course, that more kids wear helmets when they get into accidents. But another is that many give up cycling altogether. Using surveys of parents, the professors find that about 650,000 fewer children ride bikes each year after helmet laws go into effect. That's about 81,000 fewer riders for every life saved. Helmets may save lives, but the dork factor also takes its toll.People conduct their lives to a perceived level of risk. Get into a car, for example, with a full suite of crash protective devices, plus a 4-point seat belt and a mandatory helmet, and you'll be as safe at 100 mph as you used to be at 60. So you drive 100. It also helps that at 100 mph, fewer people see you swaddled in a rolling rubber room. If you think a mandatory helmet law would somehow benefit you by making cyclists wear them, think how much less likely you'll be to hit one if all the helmets were required to be bright pink.