The CycleChat Helmet Debate Thread

[Big Andy]

Small wonder that helmet manufacturers don't make claims for their product's efficacy, when every failure is trumped as a success.

I suppose it depends how you define failure and success. For me the fact I did not sustain any head injury despite a substantial impact rather suggests a success. I cannot see how it could be considered a failure. Is it so hard to accept that a helmet may have prevented a head injury? Such a dogmatic point of view rather prevents sensible meaningful discussion.

 

[Justinslow]

A failed helmet means it failed in its intended purpose - to absorb the energy of impact and reduce the impact forces (or more strictly, impact acceleration) to your head. The only mechanism by which impact forces can be reduced is by compression in the helmet. That your helmet cracked suggests that it failed in a brittle manner and did not compress. A "failed helmet" as you put it, does not offer any meaningful protection against serious injury whatsoever. In fact, by making it more likely that your head will collide with another object, it makes injury more likely.

ETA: It would be churlish not say "I'm glad you weren't badly hurt", so I'll just say I'm glad you're still here posting (and not drinking through a straw!) You helmet at least saved you from an unpleasant scalp injury so it would be wrong to suggest that it was useless.

But how do you know in which order it happened? Did it compress first then crack, at which point it had absorbed the initial "dangerous" impact?

Words you use such as "suggest" - suggest to me that you don't really know the answer. Nobody knows whether the helmet prevented significant injury, but the fact that big andy did not receive significant injury to his head tells me that his helmet was worth wearing on this occasion. Rather his helmet crumpled and cracked than his head!

Edit @Big Andy you beat me to it with your post above.

 

[srw]

A helmet that cracks will has a diminished ability to compress. A crack is not a good thing to see in a structure that is designed to deform in a controlled manner. Brittle fracture is in no way controlled.

Disappointed at the lack of long technical words, McW. I think you need to up the mad scientist quotient.

 

[srw]

I suppose it depends how you define failure and success. For me the fact I did not sustain any head injury despite a substantial impact rather suggests a success. I cannot see how it could be considered a failure. Is it so hard to accept that a helmet may have prevented a head injury? Such a dogmatic point of view rather prevents sensible meaningful discussion.

The two words you contrast are being used in different senses.

It "failed" in a physical sense - it cracked when it's supposed not to crack. "Success" as a helmet in this sense is not-cracking.

It might have "succeeded" in a protective sense, but that's a view based on no evidence.

 

[srw]

I'm not sure about that. To whatever extent the polystyrene crushed, that presumably absorbed the same energy whether or not it also cracked?

I was taking a bit of a punt. But my reading of what @McWobble says is that it was a reasonable punt. Despite a bit of energy absorption (polystyrene foam doesn't need a lot of energy to deform slightly) enough energy made its way through to cause a crack.

 

[srw]

Stating as fact that my skull was not at risk .

But I didn't. That bit was covered by " my suspicion is" at the start of its paragraph.

 

[Justinslow]

but that's a view based on no evidence.

Apart from the fact that his head is not damaged........

 

[srw]

Apart from the fact that his head is not damaged........

Which isn't evidence for the helmet providing protection. Nor is his left big toe, but you're not claiming that his shoe protected him. His midriff is damaged, but nobody is observing that he wasn't wearing body protection.

 

[ufkacbln]

The real issue is where the helmet cracks

There is an increasing trend for fashion at the expanse of function

As helmets have less and less material, the remaining material becomes denser and less able to absorb energy in order to support the shape, and there are now thin vulnerable bridge s between the vents

Realising that there is now so little material the design is unable to support itself, There is then a carbon cage inserted to provide the structure and support that the helmet itself no longer provides, and again' these frames have no contribution to energy absorption


Look at the "helmet saved my life" photos and the majority of these fractures are at these weak points

Then ask why the manafacturer are being allowed to develop products that are less and less able to perform their principal task

 

[ufkacbln]

Not sure if this has been posted already, apologies if it has

http://www.bbc.co.uk/news/world-europe-37213884

Is that the photo of the guy with both hands
and one foot on the floor and people claiming his head was the first point of contact?

 

[Justinslow]

Which isn't evidence for the helmet providing protection. Nor is his left big toe, but you're not claiming that his shoe protected him. His midriff is damaged, but nobody is observing that he wasn't wearing body protection.

Yes but this a "helmet" thread not a "ribs" thread.

 

[Justinslow]

What baffles me is that some of you believe that a helmet when strapped to 13 odd stone (sorry Andy no idea what you weigh) hits the ground with some of that 13 odd stone behind it - will show NO damage?

 

[RichK]

...

Then ask why the manafacturer are being allowed to develop products that are less and less able to perform their principal task

but I suspect the principal task is (only) to pass the certification test

 

[Justinslow]

Which isn't evidence for the helmet providing protection. Nor is his left big toe, but you're not claiming that his shoe protected him. His midriff is damaged, but nobody is observing that he wasn't wearing body protection.

This post sums it up for me, utter refusal to accept that a helmet can sometimes prevent more serious injury.
I'm big enough to admit helmets have their shortcomings, that they have limited protection abilities, that I don't always wear a helmet. But @Big Andy has explained the situation regarding his accident shown us pics of his helmet, told us that he hit his helmeted head on the Tarmac, explained how his helmet prevented more serious injury yet @srw will not accept that. There is no way in this case that it can ever be "evidenced" or "proved" that the helmet did some good, that is the problem here. Some people will be gracious enough to admit helmets can help, some won't.

 

[martint235]

This post sums it up for me, utter refusal to accept that a helmet can sometimes prevent more serious injury.
I'm big enough to admit helmets have their shortcomings, that they have limited protection abilities, that I don't always wear a helmet. But @Big Andy has explained the situation regarding his accident shown us pics of his helmet, told us that he hit his helmeted head on the Tarmac, explained how his helmet prevented more serious injury yet @srw will not accept that. There is no way in this case that it can ever be "evidenced" or "proved" that the helmet did some good, that is the problem here. Some people will be gracious enough to admit helmets can help, some won't.

Helmets can help to reduce friction burns and grazes etc but for as long as there is no real testing or evidence, if you walk away from a crash wearing a helmet you may as well say that your lucky underpants prevented you experiencing a serious head injury