[QUOTE 4951598, member: 43827"]You like to live up to your tag line don't you?
Here are some pics of the helmet. I don't care whether my helmet split, crushed or compressed - it broke! I don't know whether the doctor I saw knows as much about biophysics as you, but he knew a lot about medicine and head injuries and more importantly, he was there looking at the injury, rather than pontificating about it on the internet.
I tried reading some of the stuff you suggested, in between going out to watch the end of the Tour, plus other bits of research and like most BF contributors I choose to put more emphasis on the bits that reinforce my gut feeling. For example some bloke called Mills said a helmet would reduce the lha to less than 200g in an impact with tarmac at an impact velocity of 6.6 ms. Now I haven't a clue what all that means but it sounds good to me so must be right!
I now realise how cavalier I have been over the years with the efficacy of equipment I have used. For example I never read the research evidence of the effectiveness of the condoms I used, or safety goggles in the workshop. Foolishly I saw the kite mark and just believed they worked, so must just have been lucky not to have had more kids, or lost an eye. I am grateful for your interest as I know you are just looking after my welfare, rather than trying to prove me wrong and you right.
Please read the last two paragraphs of my op. I am no helmet zealot.
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Thank you for starting off with the customary snide remark.
It in no way follows that being able to look after injuries gives a comanding insight as to how they are caused, or what engineering measures can be used to mitigate against them. Note that I said "engineering". Because how materials and structures behave when loaded to the point of failure is most definitely the realm of engineering, and materials science. Both skulls and helmets are structures and the response of both can only be understood using the usual tools of the materials scientist or engineer. Which is why crash test dummies are designed in the light of many decades of sound biophysical data rather than the opinion of some random doctor.
Your photos are actually quite illuminating. First, there is no evidence whatsoever of crushing. Which means that your helmet did very little to reduce the impact forces (and that comes from a straight forward application of Newton's Laws of motion). What is evident is that the (presumably) polycarbonate shell failed in a different place to the expanded foam interior. This points to failure through high shear loading. Impact with the ground with a fair lateral velocity would cause just such a loading - and it is a very common - probably the most common - sort of impact. This sort of impact imparts a considerable rotational acceleration to the head - something a helmet unable to meaningfully mitigate against. Also note that rotational acceleration is type of force which cause the most serious brain injuries. One such, and it is common, is diffuse axonal injury. Most victims die, and of those who survive, very few recover sufficiently to be able to return to an independent existence.
It's a shame you choose to view this as an exercise in point scoring: there is a debate that urgently needs to be had as to the role of helmets in cycling safety. An informed debate can only be had with proper science, not opinions. Whilst this dogmatism that helmets save no matter what the circumstance persists, there will be little or no effort made to address the real issues (casual disregard of safety by the motorist and an infrastructure hostile to the needs of vulnerable uses such as pedestrians and cyclists being foremost). That is unlikely to happen for as long as helmet wearing is seen as a panacea.
