OK TJ I’ll grant you there appears to have been a tad more research done that I thought, I also agree that it doesn’t seem complete and a lot is out of date by now, the conclusions as presented do leave a little to be desired, like you say both sides of the debate can and do put their own spin on it…
I read it as the balance of probability still being that a helmet will reduce the riders risk of brain injury, primarily through impact, however there is some evidence to show in certain circumstance it may exacerbate rotational injury, the 35-50% chance while it may sound like quite a broad spread is actually pretty precise given the massive list of variables affecting a cycle accident, so ‘m not too sure their analysis is wide ranging enough, the TRL testing only looks at one set of crash geometry (8.5m/s at 15º as they describe it), it would be good to see simulations for various differing types of cycle crash, with a full dummy not a dismembered head form; obviously resources, time and the scope of the research all affect this…
I took from what I read that the bigger your noggin the greater risk you are at (helmeted or un-helmeted) of rotational injuries, due to larger head mass and providing a bigger moment, it sort of suggested that large head size (which you can do very little about) provided as much of a potential risk to a cyclist as a Pin head wearing a bulky helmet…
It also suggests to me that more rigid shells (Dirt jumpy piss pot style ABS jobbies perhaps) could be better with Oblique impact from a rotational injury POV as the outer shell deforms less in and oblique impact giving less transfer of liner-rotational motion, making them closer in some ways to a Motorcycle helmet than a “traditional” XC style, thin shell lid, have I understood that correctly?
Question; would I be right in believing all current Standard helmet tests (Snell, ANSI, etc) only look at direct impacts, nothing oblique?
I have to say I’m still in favour of compulsion, as I think on balance helmets reduce injury risk more than they exacerbate it, however I will admit that neither position is totally unequivocal…
I do still think all of the evidence is insufficient…
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