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PostPosted: Thu Jul 04, 2013 10:29 pm 
retrobike rider
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An hour ago I implied that there is a scandal where we are all being ripped off by being sold helmets that do not protect against brain damage and concussion. This is not just my opinion but one also held by many experts in brain injury and health & safety. The problem is also well understood by the helmet manufacturers.

Here is some data from testing the effects of rotational acceleration otherwise known as angular acceleration on actual dead human brains:

An angular acceleration of 7,900 Radians/Second/second = 80% chance of brain injury/concussion

An angular acceleration of 5,900 Radians/Second/second = 50% chance of brain injury/concussion

An angular acceleration of 4,500 Radians/Second/second = 25% chance of brain injury/concussion.

7mph oblique impact to a helmeted cyclist = 10,000 Radians/Second/second

7mph oblique impact to a bare headed cyclist = 10,000-11,000 Radians/Second/second

This data explains why increased helmet use has not reduced the incidence of brain damage caused by oblique impacts that cause the brain to rotate inside the skull.


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PostPosted: Fri Jul 05, 2013 12:16 am 
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I was watching this https://www.youtube.com/watch?v=VzZkKE9Z35g which is loaded with crashes and endos.

Interestingly, the number of full direct impacts with the helmet first to the ground is zero; albeit there is one nasty one.

Typically, the head is rolled across the surface (at most) and the lower parts of the body are taking the majority of the impact first - shoulders, arms and hands first naturally to try and protect the head. Probably a few stiff necks the day after too.


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PostPosted: Fri Jul 05, 2013 8:26 am 
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At last a scientific approach! :lol:


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PostPosted: Fri Jul 05, 2013 9:39 am 
King of the Skip Monkeys
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Darwinism doesnt come into it - we have the choice. I dont feel confident that a helmet will offer any protection when I am out. I often feel more exposed because of it.

I only feel the need to wear one on group rides simply because the chances of hitting something/one goes up a bit and the you get a bit overconfident now and again... :oops:

Back in early 1986, my head had to be superglued back together because of a nasty cheap racer - my then parents decided one of those new fangled ATB's should help.

I bought my first helmet in 2011, I had never felt the need for one previously and it was only on the insistence of John that I get one for RB rides.

To win one of these you have to be really stupid: http://www.darwinawards.com/


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PostPosted: Wed Jul 10, 2013 5:23 pm 
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http://www.pistonheads.com/gassing/topi ... e%21&mid=0

"Sensible Helmet Debate" - you'd better believe it.


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PostPosted: Wed Jul 10, 2013 11:11 pm 
retrobike rider
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Woz wrote:
I was watching this https://www.youtube.com/watch?v=VzZkKE9Z35g which is loaded with crashes and endos.

Interestingly, the number of full direct impacts with the helmet first to the ground is zero; albeit there is one nasty one.

Typically, the head is rolled across the surface (at most) and the lower parts of the body are taking the majority of the impact first - shoulders, arms and hands first naturally to try and protect the head. Probably a few stiff necks the day after too.

The first thing that I noticed about the crashes shown in this video is how good riders are at protecting their heads. Either, they have all been practicing, or the human instinct to protect the head is strong.

Another observation is that rotating, rolling, tumbling etc, are all words that describe the motion of the falling riders and their heads. Falls where the head falls vertically hitting the ground square on and stopping abruptly, similar to those seen in current helmet testing, are nowhere to be seen.

Which is more realistic?
The rotational impacts as seen in this video?
http://www.youtube.com/watch?v=w5uQtxaXOyM

Or the straight line impacts that are seen in tests used by helmet standards regulators and most manufacturers?
http://www.youtube.com/watch?v=mczLYloFkfk


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PostPosted: Thu Jul 11, 2013 7:05 am 
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Graham.

How many cyclists in the UK were seriously injured last year as a result of rotational movement of their helmet upon impact?


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PostPosted: Thu Jul 11, 2013 1:21 pm 
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I don't think about my lid when I'm riding. It's there but doesn't change my behaviour. I just choose to wear it as it has little impact on my riding but might make a difference to my injuries should I come off. If it was uncomfortable Or restrictive I might think differently.


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PostPosted: Thu Jul 11, 2013 10:28 pm 
retrobike rider
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Russell wrote:
Graham.

How many cyclists in the UK were seriously injured last year as a result of rotational movement of their helmet upon impact?

The problem is that despite the large number of studies into bicycle helmet safety, non that I know of have ever found the actual ratio of rotational and linear brain injury. Though the prevailing evidence is that most brain injuries result from rotational forces. As the two forces produce characteristic and distinct injuries it may be possible to differentiate between them in brain scans. In postmortem examinations linear impacts cause cause brain damage mostly at the point of impact whilst rotational injuries are found in multiple locations throughout the structure of the brain.

Current research using corpses has found that rotational accelerations cause brain damage in much less powerful and lower speed impacts than those seen in linear collisions. As a result a helmet that should protect you from a 14mph linear impact will still cause brain damage when involved in 7mph rotational impact.

It is crucial that the real life causes of brain injury are understood so that helmet designers can produce effective helmets. Many researchers have tried using dummies, computer modelling, dead bodies and even live monkeys, but non of this has told us what actually occurs in real life accidents. If an examination of existing injury diagnosis and brain scans could provide useful evidence, it should be done.
In truth it should have been done years ago.


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PostPosted: Thu Jul 11, 2013 10:38 pm 
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Quote:
It is crucial that the real life causes of brain injury are understood so that helmet designers can produce effective helmets. Many researchers have tried using dummies, computer modelling, dead bodies and even live monkeys, but non of this has told us what actually occurs in real life accidents. If an examination of existing injury diagnosis and brain scans could provide useful evidence, it should be done.
In truth it should have been done years ago


I suspect that making the head two inches bigger all around, as current helmets do, will not be a great idea. They increase the chance that your head hits something in the first place and may provide more leverage on the head, causing faster and more severe rotation. The skull itself is pretty tough, as anyone whose tried beating someone to death with a cricket bat will tell you. Perhaps we should be looking at slimmer, closer fitting helmets, that improve the heads ability to slide, or glance off objects, rather than focusing on cushioning direct impacts.


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