[cyanoacry]

I'm extremely skeptical of this viewpoint, if only due to the fact that the energies involved in car crashes are an order of magnitude larger than those involved in bike accidents.

Intuition says that a car might be traveling (on average) double the speed of a bike--which puts us at 4x the amount of stored energy in your head which can dissipate. Unfortunately, bicycle helmets are almost definitely useless at this speed.[1]

It's also unclear if the same mechanisms for brain injury apply, though I don't have any statistics on this matter. My impression is that strict blunt force trauma is no longer the prevalent mechanism for injury in cars---you're more likely to get whiplash or some sort of quick rotation that puts you in a coma due to the brain sloshing around. Helmet or no helmet, it's difficult to protect against rotational modes.

So even if we went with this article's suggestion of wearing helmets in cars, there's a large possibility the numbers wouldn't look any better. I wear a helmet on a bike because it maximises my protection given the amount of inconvenience it gives me. Nothing about car statistics invalidates this trade.

[1] http://www.helmets.org/limits.htm