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PostPosted: Thu Jul 11, 2013 11:50 pm 
retrobike rider
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From the research I have seen it may be possible that a thin helmet designed to rotate relative to the wearers head may well be able to reduce the incidence of brain injury in cycling accidents. However, it could not presently be sold because it would not pass the current impact tests. It is also possible that a bobble hat could provide more protection against sudden rotational accelerations and decelerations of the head than current helmet designs.

The question is what are the actual risks of banging the head hard versus the head being made to rotate or stop rotating suddenly? If the risk of the former is low, and the risk of the latter is high, then current helmet designs and standards have a big problem.

Some research, including the inspection of helmets after accidents, conclude that the foam was rarely, if ever, compressed as expected. This suggests that the dense foam currently used is too stiff and so not in fact protecting the brain. This is born out by instances where the helmets of brain damaged victims are not damaged.

Only through a thorough understanding of what causes brain damage can effective solutions be identified. These solutions may in fact be very simple. Even a elastic net stretched over a current helmet would stop it from suddenly gripping the ground. Maybe even a spray on coating? But it is the regulators of helmets that need to get the facts straight. Only then can we have new test standards based on hard nosed science, and not the current finger in the air style guesswork.


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PostPosted: Fri Jul 12, 2013 3:45 am 
Gold Trader / MacRetro rider
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Ive started wearing my lid 8)

Nothing to do with this thread though :lol: more a case of it being really hot and the vents on the lid are great at channeling it into little cold drafts :D


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PostPosted: Fri Jul 12, 2013 2:35 pm 
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I've started wearing a white cloth cap to keep the sun off my bonce.


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PostPosted: Fri Jul 12, 2013 4:28 pm 
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GrahamJohnWallace wrote:
From the research I have seen it may be possible that a thin helmet designed to rotate relative to the wearers head may well be able to reduce the incidence of brain injury in cycling accidents. However, it could not presently be sold because it would not pass the current impact tests.


You can buy anti-rotation helmets. Passing the current impact tests is so easy you could get a crumpet to pass it.

I wouldn't bother with most of the anti-rotation designs because, like every other helmet, they fail at too low a velocity. Rotation from low speed impacts is only going to cause brain damage if you are freakishly unlucky or repeat them frequently, in the manner of NFL players.

Quote:
It is also possible that a bobble hat could provide more protection against sudden rotational accelerations and decelerations of the head than current helmet designs.


Actually scalp movement and tearing provides built-in anti-rotation.

Quote:
Some research, including the inspection of helmets after accidents, conclude that the foam was rarely, if ever, compressed as expected. This suggests that the dense foam currently used is too stiff and so not in fact protecting the brain.


That's a good question to ask... but in reality, no: most of the helmets recovered have cracked shells, and once the shell cracks then liner compression won't occur. That's why I'd recommend wearing a Snell B90 or 95 foam hat if you are going to bother wearing one - the tougher impact tests provide a much better guarantee of shell integrity.

Quote:
This is born out by instances where the helmets of brain damaged victims are not damaged.


Brain damage will almost always be via rotation, so a current helmet will be irrelevant.

Quote:
Only through a thorough understanding of what causes brain damage can effective solutions be identified. These solutions may in fact be very simple. Even a elastic net stretched over a current helmet would stop it from suddenly gripping the ground.


There is company that makes decent anti-rotation motorcycle helmets. They use a sliding membrane - it adds about 100Eu to the price. But for cycling helmets, worrying about rotation is pointless because they don't have the shell integrity to make it worthwhile.


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PostPosted: Sat Jul 13, 2013 9:18 am 
King of the DuckBoard
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Woz wrote:
I've started wearing a white cloth cap to keep the sun off my bonce.


same here. bloody sun burn is a mare. i still wont wear a helmet. so the helmet 'mafia' can piss off.


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PostPosted: Wed Jul 17, 2013 5:10 pm 
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just remembered I found these guys when wondering how long they last

http://www.helmets.org/bhsi_faq.htm and some thoughts on stats

http://www.helmets.org/stats.htm#boston


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PostPosted: Sat Jul 20, 2013 10:14 pm 
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A guy in our bike club had a bad accident today during the club ride. Went over the bars, possibly something to do with a front brake block coming out. He was going over 32mph. Helmet cracked, huge bump on head, ambulanced to hospital, ecg & ct scan came back ok luckily. I think it may have been a different story without the helmet. I'll transfer pictures of the helmet if any come up.


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PostPosted: Sun Jul 21, 2013 4:04 pm 
retrobike rider
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I am very pleased to hear that he is OK, and feel sure that the helmet helped.

However cracking of the foam is actually a sign that the helmet did not perform as intended.
Helmets on test rigs will usually fail the test if they crack.
This is because the foam is designed to compress on impact, absorbing energy as it does so, and once cracked the foam will then fragment instead of compressing. Cracking is a sign that the helmet has been subjected to tensional, bending or shear forces that it is not designed to absorb. Once cracked the integrity of its structure is substantially undermined.

In theory, by designing helmets to rotate relative to the head like on the MIPS designs should also reduce the likelihood of cracking.


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PostPosted: Sun Jul 21, 2013 6:46 pm 
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GrahamJohnWallace wrote:
I am very pleased to hear that he is OK, and feel sure that the helmet helped.

However cracking of the foam is actually a sign that the helmet did not perform as intended.
Helmets on test rigs will usually fail the test if they crack.
This is because the foam is designed to compress on impact, absorbing energy as it does so, and once cracked the foam will then fragment instead of compressing. Cracking is a sign that the helmet has been subjected to tensional, bending or shear forces that it is not designed to absorb. Once cracked the integrity of its structure is substantially undermined.

In theory, by designing helmets to rotate relative to the head like on the MIPS designs should also reduce the likelihood of cracking.


FFS give it up, the guy is alive so therefore the helmet did it's job, no matter what the foam did or didn't do. And I doubt he'll be wearing the same one again cracked or not.


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PostPosted: Sun Jul 21, 2013 6:52 pm 
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That made me chuckle!


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