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PostPosted: Sun Jul 21, 2013 7:01 pm 
retrobike rider
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Tazio wrote:
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.

I think that you are seriously missing the point. Which is we are all being sold helmets designed to pass poorly conceived tests when they should be designed to protect our brains.

The fact that helmets protect anybody from brain injury is a mater of total luck and not design.


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PostPosted: Sun Jul 21, 2013 7:51 pm 
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Here is an experiment we can all try at home.

Take a sponge or a piece or expanded foam.

Take a ruler and hold it next to the sponge/foam.

Take some brittle plastic sheet and lay it on top of the sponge/foam.

Push down from above with a blunt object.

Note the compression of the sponge/foam as you compress the stack.

At some point the plastic will crack.

Now, did it happen BEFORE or AFTER there was some compression of the sponge/foam?


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PostPosted: Sun Jul 21, 2013 8:23 pm 
retrobike rider
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gtRTSdh wrote:
... He was going over 32mph. Helmet cracked, huge bump on head,...
I am assuming that at 32mph on a helmet designed for a 14mph linear impact we are talking about the foam cracking and not just the thin outer shell. This would be similar to that shown in the helmet at the start of this thread.

Cracking of the shell without compression of the underlying foam suggests that the helmet has gripped the road and ripped. Whilst a cracked shell and compressed foam inner implies that some form of point loaning has occurred. Maybe from a curb edge.

In most 6ft drop tests on modern helmets neither the inner or outer shell cracks.


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File comment: Helmet with cracked foam inner
helmet.jpg
helmet.jpg [ 115.28 KiB | Viewed 102 times ]
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PostPosted: Sun Jul 21, 2013 11:17 pm 
retrobike rider
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just been reading some of the comments, yes helmets save your bonce, fact.
if a helmet cracks then it has saved your head from being cracked.
i have read a lot of v.d. in this thread.
i wear a helmet on club rides, because its the rules.
i choose to not wear one when i ride on my own.
its a gamble but so far i'm good.


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PostPosted: Sun Jul 21, 2013 11:23 pm 
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videojetman wrote:
i choose to not wear one when i ride on my own.
its a gamble but so far i'm good.


My wife and I like to turn the lights out and throw knives at each other. So far so good.


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PostPosted: Sun Jul 21, 2013 11:31 pm 
retrobike rider
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highlandsflyer wrote:
My wife and I like to turn the lights out and throw knives at each other. So far so good.

glad to hear it.


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PostPosted: Sun Jul 21, 2013 11:37 pm 
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So we're back to Darwinism.


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PostPosted: Mon Jul 22, 2013 12:00 am 
retrobike rider
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videojetman wrote:
just been reading some of the comments, yes helmets save your bonce, fact.

Fact: They reduce scull fractures.
Fact: They reduce lacerations and bruising to the face and head.
Fact: There is no real world evidence that I have seen that they reduce the chance of concussion and brain injury. I can show lots of data that show that increased helmet use does not lead to a corresponding reduction in incidence of concussion and brain injury. Where is the data that contradicts this?

videojetman wrote:
if a helmet cracks then it has saved your head from being cracked.
The foam used in helmets is chosen to withstand compression in a test impact. However the effect of the tension, bending, and shear forces that the helmet will probably be subjected to in a real accident are not tested. As a result, helmet foam will absorb comparatively little energy when ripped apart. Try it with some polystyrene. It is extremely difficult so squash but can be easily puled, twisted, bent or ripped to pieces. In order to protect properly it would need to stretch, not crack.
The reason why it is used is because it is cheap and absorbs through compression across the wide range of temperatures and humidity levels required by tests.

videojetman wrote:
i have read a lot of v.d. in this thread.

To say that people are talking v.d. without being specific and producing counter arguments is a complete cop out.

I say that the vast majority of helmets we all spend millions do protect but not against brain damage and concussion and that we are being conned into believing that they do.
Where are the arguments and statistics to prove me wrong?


Attachments:
Cambridge Helmat stats.png
Cambridge Helmat stats.png [ 71.65 KiB | Viewed 141 times ]
Western Ausralia head injury trends 1973-1998.jpg
Western Ausralia head injury trends 1973-1998.jpg [ 73.2 KiB | Viewed 141 times ]
New Zealand head injury trends 1988-1996.jpg
New Zealand head injury trends 1988-1996.jpg [ 95.59 KiB | Viewed 141 times ]
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PostPosted: Mon Jul 22, 2013 12:21 am 
retrobike rider
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Looks like rat banes son's helmet worked.
Which is a good thing.


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PostPosted: Mon Jul 22, 2013 1:26 am 
retrobike rider
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videojetman wrote:
Looks like rat banes son's helmet worked.
Which is a good thing.

It is definitely a good thing that rat bane's son was not injured! There is some evidence of crushed foam so the helmet did work. Although the split in the foam is not what the designers intended to happen.

But what about the thousands of other people worldwide who though wearing helmets are suffering brain injuries and concussion? Many where the helmet foam is not showing signs of energy absorption.

Do we just accept these injuries?
Or do we expect the helmet designers and legislators to sort these problems out?

And when helmet designers do make helmets like MIPS designed to absorb dangerous rotational impacts do we support them? Or do we carry on blindly, trusting the, badly designed in order to pass ill conceived tests, helmets that we have been sold for decades?


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