One pedestrian death caused by a bicyclist's negligence and DU explodes with anti bicycle venom..

[pnwmom]

114. One of my kids' teachers fell off a bike and suffered a serious head injury

and a seizure. At about the same time, U.W. came out with some research that helmets greatly reduced the chance of serious head injuries. The injured teacher, of course, became a huge proponent of helmets. And her example was all the proof I needed that smart people exercising reasonable caution can still get seriously hurt on a bike. (If you're ever seriously injured, it is no comfort to know that your injury was rare, particularly if it was preventable.)

In making a risk/benefit analysis like this, there are several things to consider.

How likely is the negative event?
How severe is the negative event?
How effective is the preventative measure?
How difficult (or costly) is the preventative measure?

The likelihood of a head injury to a bicycle rider may be small, but if it happens, it can be catastrophic. A helmet greatly reduces the chance of such an injury, and isn't difficult to use.

If a helmet were hugely expensive or difficult or painful to wear, that would change the equation. But, as it is, I think it's worth the minor inconvenience and cost -- and even "helmet hair" -- to wear one.