I haven't seen the study, but I don't believe the claim. I'm no Lance Armstrong by any stretch, but I've done a bit of biking here and there. And twice already,

I haven't seen the study, but I don't believe the claim. I'm no Lance Armstrong by any stretch, but I've done a bit of biking here and there. And twice already, I've had crashes that could have been serious without a helmet. It's too easy to fly over the handle bars. Once was a slight layer of mud over a sidewalk, which was completely unpredictable to me (but won't ever be again). Extrapolating from my own experience (which is by no means a gold plated double blind study, but which still presents valid evidence about reality), the physics of a bicycle make the rider prone to crashes that involve head impact. You can cry "anecdotal," but I'll answer "common sense." Besides, the people who argue that evangelizing helmet-free riding will lead to more riders actually acknowledge that helmets are important ... they just want to spread a different story publicly.