I have avoided all helmet debates! That is partly because I'm a fence sitter, and partly because I avoid most heated arguments on the forum. But I'd like to ask what people think of
this article.
Not much. You need to read the
paper it refers to (not for the squeamish so stop reading now if you are). But the problem with the paper can be summed up with this one line from it:
Despite the conclusively proven protection offered by bicycle helmets, usage rates remain abysmally low.
No agenda with the authors there then.
They took child cadaver skulls, soaked them in room temperature water for 24 hours, filled them with lead weights to get them up to 4lbs weight and then poured in polymer resin to fix the lead weights in place. They then used those in place of the standard head-form in a cycle helmet testing rig to find out they replicated [1] the result of the helmet test rig. Which was never in doubt.
What is in doubt is how meaningful that is in the real world because here is the effect of child helmet wearing rates on child head injuries in Ontario, Canada. i.e. whatever all these contrived laboratory tests show, in the real world the effectiveness is zero.
[1] Actually they didn't replicate the result of the standard headform tests because their accelerometer didn't have enough range to do the measurements for anything over a drop of 9 inches compared to a drop of 1-2m in actual helmet tests. Why they didn't buy an accelerometer with a suitable range to do the experiment is beyond me but such is the nature of poor science. What they did find though was an unhelmeted skull underwent an deceleration of 440±79G when dropped 6" which is about 50% above the maximum tolerance level of the brain. Now do we really believe that kids will for certain be killed or suffer traumatic brain injury if they hit their heads falling from a height of 6" or do we think their experiment could be just a little bit not representative of reality?
They also did a resistance to crushing forces test and I am still trying to work out what on earth the results are. These are they as quoted in the paper:
Compression Testing
Evaluation of the helmet-only compression data showed initial cracking that occurred in the range of 100–200 lbf. The average cracking force was found to be 140 lbf. The skull and helmet assembly could not be crushed in the compression stand even under the maximum force experienced by the load cell (470 lbf). It could be seen during testing, however, that the helmets without the skull cracked at approximately 190 lbf. This is consistent with data from the compression testing provided by the manufacturer of the selected helmet used during the tests. The unhelmeted skull underwent catastrophic failure during testing, experiencing a maximum load of 520 lbf.
So the bare empty skull cracked at 50lbf above the maximum force of the load cell? And what would the helmet plus skull have done if exposed to that same force? And do bare helmets crack at 140lbf or 190lbf. Totally confused and confusing.
