But in the world's most popular biking cities, particularly in Europe, very few bikers wear helmets. And there are good reasons for that: biking, it turns out, isn't an especially dangerous form of transportation in terms of head trauma. And the benefits of helmets may be overstated. While they do protect your head during accidents, there's some evidence that helmets make it more likely you'll get in an accident in the first place.
I bike most days, and feel conspicuous when most of the other bikers I see are wearing helmets. This morning I counted 5 riders without helmets out of 58 total (not counting myself and an unhelmeted woman walking her bike).
Anecdotes are compelling, but don't give a clear idea of the big picture. How great is the risk? Should we consider the number of injuries per trip, per mile, or per hour? What do we compare to?
The studies are clear in a certain narrow way, with conclusions like "Wearing a helmet dramatically reduces the risk of head and facial injuries for bicyclists involved in a crash, even if it involves a motor vehicle." But the same could probably be said of pedestrians and people in cars. Why don't we wear helmets all the time?
See also mk's link to a paper by two authors who "dread questions about bicycle helmets."
Want to hear something funny? I suffered a TBI (Traumatic Brain Injury) back in 2012. I was jumped by some kids and smacked with a 2x4 off of my bike. I was one of three cyclists this happened to that year and the police did nothing. Anyways, A lot of people always say "I bet you'll wear a helmet now". I've put thousands of miles on my bike and just don't particularly like helmets for a variety of reasons. People don't seem to understand that in most situations a helmet isn't required. I remember reading awhile back that the #1 injury for people who compete in the tours was a broken collarbone (could be wrong on this, if I am please let me know). This was before they started to require helmets for the full length of the race.