Mike Sales wrote:The one time I banged my head on the tarmac I was unhurt, presumably due to my cotton Festina casquette.
As a teenager, before helmets were heard of, I banged my head on the tarmac when wearing nothing at all on it. I was checked for concussion in hospital and given the all clear. Otherwise I was unhurt. Presumably my hair saved me.
This is an example of the kind of accident in which a helmet could be damaged quite significantly (should be; that's what's supposed to happen), without necessarily achieving any protection. It's also an anecdote, and it's very hard to be sure what would have happened with a helmet.
Which is why some of us are interested in the national-level comparison of head-injury rates before and after helmets became widespread. The analysis is complex, and conclusions vary, but overall it doesn't seem very convincing. A few analyses show things actually getting worse*, which is the background to explanations such as some mentioned up-thread, for how helmets could make life more
dangerous. Of course, others show significant benefit. Those showing really large benefit are not really credible (it turned out that they were comparing kids riding on the streets against those riding in parks, that kind of thing).
The number of people claiming benefit from helmets in crashes is itself a problem. Head injuries tend to be quite well-reported, so we should have a decent idea of the casualty rate before helmets (although cycle accidents are not always separated from others in hospital recording). When you've got loads of people telling you that their helmets have saved them, but you know that the chances of knowing someone who had been killed or (head-)injured have always been mercifully low, it's hard to explain the difference.
* If memory serves correctly, the first of these was in the Journal of Product Liability
in 1986, albeit when helmets were of a very different design**. There's also been a lot of correspondence in the British Medical Journal
, on both sides of the debate.
** But of course designs are changing again. After years of sceptics worrying about rotational injuries as a possible explanation for the statistics mentioned above, MIPS
is becoming de rigeur. If it's necessary, that seems to be in conflict with the historical claims made for massive benefit from helmets without MIPS.