Who wears a helmet?

[Drago]

Has anyone noticed that a common theme of these threads is that those who wear helmets seem to crash a lot.

By crashing a lot, you surely mean 'not crashed since I was a kid'?

 

[mattsr]

Leading to the not unexpected conclusion that helmet wearers get injured more.
Some of us knew that already

Do please show me some statistics that show that:-

a) Helmet wearers crash more

and

b) Helmet wearers get injured more.

I'd be fascinated.

It's surely inevitable that on a thread discussing helmets, that those sensible folk who wear them will recount the occcasions on which a helmet has prevented or lessened an injury. If it is then possible to extrapolate from a small number of posts, on a forum that is itself representative of a relatively small number of cyclists, that either of the above are true, then I'm a banana.

 

[mattsr]

It was a reference to these threads where people often post anecdotes about how they fell off, hit their head but everything was all right because the helmet split in two which shows it must have saved them from a certain broken skull/death etc. What you don't get is loads of stories from people who fell off but were not wearing a helmet. The obvious conclusion is that helmet wearers must fall off more.

Or those that fell off without wearing a helmet are no longer capable of communication......

 

[srw]

Or those that fell off without wearing a helmet are no longer capable of communication......

And that is one for Greg Collins. Is there a Greg Collins in the house and capable of communication?

 

[martint235]

It's surely inevitable that on a thread discussing helmets, that those sensible folk who wear them will recount the occcasions on which a helmet has prevented or lessened an injury. If it is then possible to extrapolate from a small number of posts, on a forum that is itself representative of a relatively small number of cyclists, that either of the above are true, then I'm a banana.

See, it's very difficult to say that a helmet "has prevented or lessened injury" without actually proving it which is difficult cos they were wearing a plastic bucket on their head at the time. I've fallen off a few times without wearing a helmet. Strangely enough the most common bone I break is my rib. Perhaps I should wear body armour. I've never had a fractured skull in my life.

 

[Drago]

And what causes a helmet to crack?

 

[Little yellow Brompton]

Even wearing a helmet, a heavy impact to the skull can cause damage. Remember that a cycle helmet is only a relatively thin layer of polystirene in a hard shell designed to protect against low speed, low impact scenarios.

It's not a "hard shell" no matter what the manufacturers want to call it. The shell has no effect whatsoever on the performance of the helmet, only being their to make it look pretty.

A "hard shell" is found on motorcycle helmets, where the outer hard shell ,spreads the point impact load and holds the inner shock absorber lining together. The reason that cycle helmets split and shatter is not because they have "worked" but because they are really only half a helmet and the shock absorber can't take high point loads . The helmet is meant to crush, it can't crush if it splits first.

 

[Little yellow Brompton]

And what causes a helmet to crack?

Point load outside of it's design parameters

 

[Little yellow Brompton]

Or those that fell off without wearing a helmet are no longer capable of communication......

But there are only 114 ish killed a year, the vast majority of those being crushed by lorries. Year on year the number of helmet wearers increases, ( now double what it was 20 years ago) but still the number killed stays the same ( ish) and the causes remain constant , why isn't your intervention making a difference? Could it be that the intervention is not as effective as you think?

That 114 ish is relativley constant, yet I must have heard thousands of stories of " If I wasn't wearing then I woudn't be ....." Something isn't right somewhere, either those people are in general wrong or there should be thousands of deaths in the population of cyclists not wearing helmets, where do your think all these dead people are being hidden?

 

[martint235]

It's not a "hard shell" no matter what the manufacturers want to call it. The shell has no effect whatsoever on the performance of the helmet, only being their to make it look pretty.

A "hard shell" is found on motorcycle helmets, where the outer hard shell ,spreads the point impact load and holds the inner shock absorber lining together. The reason that cycle helmets split and shatter is not because they have "worked" but because they are really only half a helmet and the shock absorber can't take high point loads . The helmet is meant to crush, it can't crush if it splits first.

Sorry I meant it more literally in that the shell is harder than the foam.

 

[Little yellow Brompton]

But on the flip side I've had to tell plenty of helmeted cyclists wobbling down the road to shut up and mind their own 'kin business when they have asked me where my helmet is.

Oh yes, just like this thread, it's always those who beleive in the religion of polystyrene that start throwing the first stones...

 

[Little yellow Brompton]

Sorry I meant it more literally in that the shell is harder than the foam.

Yes , but " hard shell" has a real meaning for real helmets and the cycle helmet manufacturers like to bandy words like " hard shell" about when meaning something completey different.

 

[totallyfixed]

But there are only 114 ish killed a year, the vast majority of those being crushed by lorries. Year on year the number of helmet wearers increases, ( now double what it was 20 years ago) but still the number killed stays the same ( ish) and the causes remain constant , why isn't your intervention making a difference? Could it be that the intervention is not as effective as you think?

That 114 ish is relativley constant, yet I must have heard thousands of stories of " If I wasn't wearing then I woudn't be ....." Something isn't right somewhere, either those people are in general wrong or there should be thousands of deaths in the population of cyclists not wearing helmets, where do your think all these dead people are being hidden?

Not only that but as some on these threads are true believers in statistics, would someone please point me to those stats that show a higher incidence of head injuries [proportionally of course] before some clever marketing salesmen came along and foisted the cycling helmet upon us, and yet still cannot state in their marketing blurb that helmets are effective.
What is almost never talked about is the potential for serious injury that a helmet poses. I personally know first hand of three people who have suffered serious injury to their necks that would unlikely to have occurred if they had not been wearing a helmet, one of them died such was the severity of the rotational forces. 6 years ago I had a fairly serious accident [I have had a few ] where I went through the rear window of a car, I just missed hitting the top of the window frame, if I had been wearing a helmet this would certainly have prevented my head from continuing it's merry path through the window but would also probably [note the word "probably"] have forced my head backwards rather violently.
I am reasonably sure, but feel free to prove me wrong that rotational injuries to the neck do not come under head injuries when recording cycling accidents.

 

[Drago]

Point load outside of it's design parameters

Close enough. The word I was looking for is 'energy', but you're on the right track.

Energy is measured in Joules.

Each Joule of energy expended on compressing or cracking the helmets material, is a Joule that can not damage the human head beneath.

Cracking is simply a symptom of energy being expended. Really there are two scenarios to this. The obvious is that here is so much energy at play that the helmet cracks/fails and there is still energy from the impact left to expend and the head underneath goes on to absorb some of it, and this is naturally where injury may occur.

The opposite scenario is that he structure of the helmet retained its integrity long enough to absorb energy and protect the head, and the cracking is simply the action of the final Joules if energy being expended and the process stops there. We know this scenario exists from the people who report cracked lids but still no injury.

So it can be that if a helmet has cracked or split that it has failed to absorb sufficient energy to protect a head. But this is not always the case, and it does not automatically follow that if a helmet has split that is has not failed to absorb enough energy to prevent injury.

 

[Little yellow Brompton]

Close enough. The word I was looking for is 'energy', but you're on the right track.

Energy is measured in Joules.

Each Joule of energy expended on compressing or cracking the helmets material, is a Joule that can not damage the human head beneath.

Cracking is simply a symptom of energy being expended. Really there are two scenarios to this. The obvious is that here is so much energy at play that the helmet cracks/fails and there is still energy from the impact left to expend and the head underneath goes on to absorb some of it, and this is naturally where injury may occur.

The opposite scenario is that he structure of the helmet retained its integrity long enough to absorb energy and protect the head, and the cracking is simply the action of the final Joules if energy being expended and the process stops there. We know this scenario exists from the people who report cracked lids but still no injury.

So it can be that if a helmet has cracked or split that it has failed to absorb sufficient energy to protect a head. But this is not always the case, and it does not automatically follow that if a helmet has split that is has not failed to absorb enough energy to prevent injury.

Simplistic, you are forgetting/ignoring time and area.

The helmet cracks because it's trying to absorb X Joules over S time whereas if it was X Joules over 10X time it could compress, as it is meant to. Wasn't it Bell's engineer who wrote that he had never seen a child's helmet with compression?

The helmet cracks because X Joules are delivered by or on a point rather than the the flat forme that is used for the ( minimal) test .

Which ever way you want to dice it " My helmet cracked and it it hadn't it would have been my head" is simplistic bollocks, trotted out by parrots whose helmet wasn't protecting anything of great value.