Question:
How often have you heared of anybody hitting the ground with their head on a bicycle when the tire blew out? From my own experience on the motor bike, when the tire blows out you might fall because your wheel starts skidding. If your rear wheel skids you may eventually fall to the side, thus onto your leg possibly onto your shoulder. In this case you need to be a fair bit faster than 40 mph before the impact is big enough to bounce your head onto the ground

Answer: From the pro-helmet people I perceive either a double standard or just plain misplaced faith in automobiles. It's like the risk of head injury in a car is acceptable but on a bicycle it is not. Why take that kind of risk for a hobby? It doesn't take a special study to figure out that there are far more deaths/braindead from head injuries sustained in auto accidents either. To Europeans, requiring helmets for cyclists is more like requiring motorist helmets to Americans, not worth the discomfort and inconvenience.

Motorcycles, but in light of the death here in Marin County earlier this month of a speeding bicyclist from a head injury when he crashed because either his pedal hit the curb (the police version) or the poorly maintained bike path caught his front tire (his friends' version), I guess it doesn't matter. I guess I'm merely drawing unreasonable conclusions from the severity of the impact with which my helmeted head hit the pavement. In any case, spending months in the hospital, a la Gary Busey, isn't my idea of living.

the motorist's risk collectively is as great as the bicyclist's. that statement obscures an important difference between the two activities: there are many child bicyclists, whereas there are no "child motorists". what is an acceptable head injury rate for adults who choose to drive, is not necessarily an acceptable head injury rate for children who often have no other means of transport except the bicycle. and, as you well know, the CA helmet law is in fact targeted at children. (although i think the age limit is high enough that it also covers young adults, the point i am making is that its intention was to protect children, exactly the difference that you are obscuring when you compare head injury rates of drivers vs cyclists.) therefore, the original author's main point is interesting, but not relevant to your claim.