The CycleChat Helmet Debate Thread

[ClichéGuevara]

@Fnaar

On a helmet thread...

Mine have between 4 and 11 inches

I have never grounded either

 

[ufkacbln]

If they really want to make boxing safer, they'd get rid of boxing gloves and go back to bare-knuckles.

At Haslar we did some research that showed the perfusion of blood to the brain


The research showed that when compared to matched controls boxers suffered perfusion defects to the brain, after only a few fights

 

[ufkacbln]

@Fnaar

On a helmet thread...

......... it folds!

 

[doog]

With all due respect to both of you, being qualified to sustain life in an emergency until the professionals arrive (which is what a first aider does) doesn't qualify either of you to opine on any link between head injury and cardiac arrest. For that you'll need a neurologist or a cardiologist.

Yet it didnt stop you googlin the arse out of it and posting it on here as fact.

 

[Wobblers]

But it is, I think, plausible that the unsupported hat, being more likely to bend, is then also more likely to crack and split, whereas a supported helmet is less able to bend and therefore more likely to compress?

Why do so many helmets split? A naive view would say a point load against the skull should lead to compression not flexing. Is it because they don't fit the head well enough?

Well, that depends. I kind of left a fair bit out for reasons of brevity. And boredom (for others)! Sufficiently well constructed, an unsupported helmet may actually perform better, as it is close to the ideal - and very strong - spherical shape, so will behave elastically which allows the load to be distributed throughout the entire structure, with no stress concentrations. If you restrict that elastic response you necessarily limit the applied stress to a small region. Thus it's easier to exceed the yield stress here. Of course, cutting large holes in the structure will inevitably weaken it: I wonder how good the manufacturers' finite element models are? Or indeed if they bother...

But the usual demarking of materials into "brittle" or "ductile" actually ignores a lot of behaviour inbetween those two extremes. The materials used in lids, for instance, have distinct viscoelastic properties. That is, at low shear rates (where the load is applied slowly over a significant period of time, typically seconds or longer) the plastic actually behaves as a extremely viscious fluid. This mechanism is actually remarkably good at dissipating energy, and is the analogue for a metal in ductile deformation. At high shear rates, it behaves more akin to an elastic material. I suspect in many cases of split helmets, the very high rate of load application has resulted in the materials the lid's constructed from behaving in a elastic -and hence brittle - fashion rather than the more beneficial viscious flow regime.

 

[Wobblers]

Yet it didnt stop you googlin the arse out of it and posting it on here as fact.

Or in other words, srw took the trouble to actually research what he was talking about.

Whereas you, or RR haven't.

 

[Racing roadkill]

https://rdrf.org.uk/2015/03/20/the-michael-mason-case-a-national-scandal-and-disgrace/

TLdr: The cops refuse to prosecute a driver who killed a cyclist doing nothing wrong cos he didn't have a plastic hat on.

That's a common theme as well. Insurance companys increasingly seem to pay more attention to claims from cyclists if they are wearing a lid.

 

[ufkacbln]

Given the number of statements like:
"The injuries would have been less if they had been wearing a helmet"
"They should have been wearing a halmet"

made by Paramedics (and more senior medics) following lower limb injuries, I suspect that the knowledge of head injury mechanisms is somewhat lacking

However it would be nice to find out whether these PAramedics do give the same advice about protecting the head in pedestrian knee injuries

 

[velovoice]

That's a common theme as well. Insurance companys increasingly seem to pay more attention to claims from cyclists if they are wearing a lid.

Only to be expected, when you remember that their definition of "risk" relates to paying out money, not safety.

 

[ufkacbln]

It's more to do with the fact that the guys whack to the head caused him to get into such a state of unconsciousness, that the inevitable cardiac arrest ( not heart attack, they are different things), although a heart attack often leads to a cardiac arrest, occurred. When you are properly unconcious for any significant length of time, you will need CPR fairly quickly. The cardiac arrest part, is the inevitable consequence of a proper spark out.

Surely all of this goes back to a set of circumstances that is wider than cycling.

Given that a significant number of admitted head injuries are due to assault, and these are also the situation where a blow to cause this type of injury is more likely..... it is a classic argument for widening helmet use to pubs and clubs

 

[rvw]

Happened to notice that the boxers at the Olympics were not wearing head guards this time around.
Wondered why, and looked it up. Seems the IOC have ratified a 2013 AIBA decision to cease their use based on data that suggests they do more harm than good. Or rather that they don't help prevent concussion but do help prevent minor cuts and abrasions which in terms of severity and danger to long term health may be said to be the same thing.

See here, amongst other sources.

From that link: "One was that the head guards created a bigger target for boxers, who in turn attempted more head blows. The other was that the gear was giving boxers a false sense of security."

Eerily familiar points albeit with regard to totally different head protective equipment used in a different environment.

Also eerily familiar is that the argument rages on.

This link was posted a couple of years ago in this thread.

 

[Tanis8472]

More emotional blackmail.
Although I think skateboarding does require some degree of "protection", due to the nature of it, this is being pushed around fb by cyclists too.



https://m.facebook.com/story.php?story_fbid=1797659027157392&id=1797463160510312&_rdr

 

[srw]

That's a common theme as well. Insurance companys increasingly seem to pay more attention to claims from cyclists if they are wearing a lid.

Do you have any evidence for that rather sweeping statement?

(Clue - the answer is probably no.)

 

[EnPassant]

This link was posted a couple of years ago in this thread.

Forgive me. I have only been here 3 months or so and have missed that .
Mind you, a repetition rate as low as once every two years is a hit rate this thread can only dream of.

But interesting, that has the exact same points again, in that yes, the data shows more injury with a hat than without, but we can't say exactly why.

 

[rvw]

Forgive me. I have only been here 3 months or so and have missed that .

I wasn't trying to imply that anyone should have seen it. Almost the opposite: it's interesting (disappointing?) that an evidence-based decision in another sport which is considered to be dangerous* had received so little attention generally.

*Mike Loosemore spoke at a charity AGM just after the London Olympics, where some of the audience raised the "should women box" question - on the grounds of the danger. He pointed out that statistically, horse-riding (utterly acceptable for the small daughters of the middle-class) and rugby (ditto sons) were much more dangerous.