Question:
Many years ago, when leaving work, one of our neuropsychology postgraduates commented upon the helmet that I had bought recently. I mentioned that I didn't wear it much because it was not very comfortable and I was too self-conscious. He then pointed out that he had recently met a patient at the local neuro ward who had been a senior executive, due for promotion to a national level post; he had taken his daughter out for a ride on her new bike. Sadly, he was hit by a car and suffered brain damage that left him in permanent need of 24 hour care. The student advised me that a helmet would have reduced the severity of his head injury. Since then, I have worn my helmet as often as possible. Cycling increases the probability and severity of injury, including head injury, compared to my usual activities. Prove it. I would say "Why should I?", given it was only a personal viewpoint, but I didn't make that clear in the post. So, would you accept that I am more at risk when cycling than when allotment gardening, visiting friends on foot, biological surveying, and hill walking, since those are my usual activities?

Answer: Most serious and fatal cycling head injuries in children (the population I have analysed) happen on the roads, the rate being around ten times that for off-road cycling. The head injury rate of road cyclists and pedestrians is not significantly different. Both are higher than off-road cyclists or the general population; cars are what makes the difference. Car crashes account for one in ten injury admissions but 50% of injury deaths, so this is hardly a surprise: most injury deaths are due to head injury, this applies to all impact deaths. And, as the manufacturers to admit and the testers agree, their product is not specified for crashes involving motor traffic.

Most head injury admissions are the result of simple trips and falls, by the way. A helmet which shatters has simply failed. Polystyrene foam absorbs very little energy in brittle failure; it is designed to absorb energy by crushing. And as stated above, modern medical thinking downplays the role of straight coup/contre-coup brain injury, suggesting that closed-head brain injuries are much more likely to be the result of torsional forces, which helmets of course cannot mitigate. Further reading: The efficacy of bicycle helmets against brain injury; Curnow WJ 2003. Accident Analysis and Prevention.Just as it would be improper to drag into the debate the brain surgeon recently featured on TV, repeatedly shown riding his bike with no helmet. The experts are as divided as the rest of us. Dr Aziz Sheikh is an ardent compulsionist, still convinced that he is right even though his maths have been shown to be wrong. Dr Richard Keatinge is a former consultant epidemiologist who is equally convinced that there is no credible evidence to support any effect on serious or fatal injuries. Barry Pless, editor of Injury Prevention, ridiculed the idea of risk compensation, until his own study proved that it happens. There are no easy answers. So the correct position is to live and let live, to oppose compulsion for many excellent reasons, and to challenge anybody who makes a dogmatic statement to prove it.