Random helmet-based abuse

[pjclinch]

Please clarify.

There are a vast number of factors that have to be considered alongside presence or not of a helmet for any given ride as to whether it ends up in an ambulance, (e.g., where is the ride, when is the ride, what are the conditions, are you in a hurry, what sort of tyres do you have, what luggage do you have and how is it attached, how well do you know the route, are you an experienced rider, are you a complacent rider, who else uses that route, what transport are they using, are they angry that they burned their breakfast, etc. etc.) and these can't be accounted for on any given trip with only knowledge of how helmet wearing affects the population, though it's entirely likely their net effect is considerably greater than the presence or not of some lightweight PPE designed and specced to mitigate minor injuries to part of the head.

Most studies on effect work by comparing what happens with an intervention vs. what happens without it, but the trick is the with/without or before/after have to be pretty much identical aside from the intervention you're testing. And that's actually very hard to achieve when there are so many other variables affecting gross rider safety.

Pete.
(minor edit to hopefully add extra clarity)

[Cugel]

...
In short, not every matter we humans need to make decisions about can be informed by "studies".

Thanks for making the point. There is no value in discussing the questions in a setting where there's no commitment to evidence-based methods.

Jonathan

I think you're right. I would be very doubtful if any studies would accurately refect the type of riding that do and the environment in which I do it...
..further to this point, I would equally doubt whether or not such studies woould take into consideration other 'safety aids' which I may or may not be using.

Well, how about anecdotal studies .... ?

No, seriously.

I make my own decision not to wear a helmet for the great majority of my cycling based on my own "anecdotes" - those incidents and accidents whilst cycling in which my error, someone else's or just bad luck cause some sort of departure from my intended momentary future aboard the bike (to not-aboard the bike). About 63 years worth, inclusive of many, many kilometres in all sorts of cycling environments, tells me that I've not banged my head once, which is not the case when doing various other regular activities such a fell walking and surfing.

So, these "anecdotes" seem quite good fodder for my personal risk assessments concerning the risks of cycling (and some other activities) to my head. So far, the risks seem too small to allow a helmet to do anything other than be a nuisance and an expense. And perhaps a device for mucking up my risk assessment accuracy for the worse.

I then add the more general data concerning how much protection a helmet will offer. The base data here is what the manufacturer's say about their helmets, which can be summed up as, "They offer just a little protection for low speed falls on to flat surfaces and maybe a kerb". They also mention, perhaps in print too small, that a cycling helmet will do nothing for you in a crash with a car or if you go over a cliff (even a small one) to hit your head on the rocks below at a large velocity. Large forces in serious crashes will still squash your cycle helmeted head.

***************
Others may have a different history of relevant personal anecdotes. Some fall of their bikes "at least once a week" to quote a regular contributor here. And I rode with one or three in clubs who seemed to achieve a similar frequency of fall - although they never seemed to bang their heads, just shoulders, elbows, hips. knees and ankles. But one can easily agree that a helmet might keep such accident-prone folk from a more likely (than for the likes of me) bad headache.

All the above anecdotal stuff, though, is genuine evidence, despite what "a scientist" might think. The thing is to understand what sort of evidence it is and what decisions it can and can't actually inform.

Larger scale studies have been made of cycling helmet effects. As far as I can discern, the general conclusion seems to be that, overall, helmet wearing increases the "accident" rate but may save a few headaches (but not much else) when they occur .... but also reduces the inclination to cycle a lot. But there's so many other factors involved that even these vague conclusions seems a bit useless, really.

Personal anecdotes for personal risk assessments to oneself are it, then. Or, to repeat the now hackneyed phrase, "It's entirely a matter of personal choice".

We should perhaps ensure that the choice is personal, though, rather than the installed "opinion" of a newspaper, helmet seller, swivel-eyed helmet fan or anyone else completely bereft of any evidence for their opinion. Beware the meme-parasites getting into your eyes and ears then up to your wetware!

[pjclinch]

To me, PJClinch’s point is very clear.

The emboldened question is pretty much exactly the question I pose myself before each bike ride*, but I’m well aware that no public safety advice is ever likely to be able to answer it at a detailed, personal level, even advice derived from some far better understanding of crash dynamics, potential injury types, and the part helmets play than exists now.

*The answer is almost always “Well, it will likely reduce that already small probability to an even smaller one, and it imposes no disadvantage. so I’ll put it on.”. But, sometimes, in very hot, sunny weather the answer is “Well, it makes my head so ruddy hot in this sun that I’m more likely to get in trouble through heat exhaustion/confusion than anything else, so no, I won’t wear it, I’ll put on my broad-brimmed scarecrow hat.”. And, when I had my old shopping bike it was sometimes “I’m using the shopping bike. That thing is so slow that the energy involved in any sudden unplanned dismount is no different from when walking, so I won’t bother.” (My latest shopping bike is a lot quicker, and encourages energetic cycling).

Yes, though I'm increasingly convinced that the reasoning boils down to rationalising my gut feeling rather than being anything objective. "Gut feeling" will be a mix of knowledge, culture, personal track record etc. etc. so it's not entirely evidence-free, but chances of it being objective are pretty low!
Rationalising stuff like this is a normal human behaviour, and unfortunately so is mistaking one's rationalisations for Perfect Logic...

Pete.

[Nearholmer]

They also mention, perhaps in print too small, that a cycling helmet will do nothing for you in a crash with a car or if you go over a cliff (even a small one) to hit your head on the rocks below at a large velocity

This is one of the points that always baffles me when it’s put forward in The Great Helmet Controversy. Put bluntly: I think it’s incorrect/misleading.

One of the things often reported about incidents where a helmet comes into play at above its tested rating is that the helmet gets damaged/broken/smashed. Achieving that requires energy, so the energy dissipated in damaging the helmet is energy that isn’t dissipated in busting the head, or some other part of the anatomy.

Now, that difference in energy transferred to the head may or may not be decisive. Probably not in the “over a cliff onto the rocks below” scenario, where the total energy involved at the point of impact is likely to be so great that all sorts of horrible injuries to all sorts of bits of the anatomy will result. But, there must be a range of impact energies where subtracting the energy needed to damage a helmet from that transferred to the anatomy is useful.

Shoes are another form of PPE where this sort of thing applies. They offer complete protection to the feet in many minor, low energy unintended impacts, and/or unintended impacts in common directions, but incomplete protection, decreasing to ‘none worth considering’, as the energy levels go up, and the direction of forces, and/or force per unit area change. And, we pretty much all wear shoes for most of the time; we don’t eschew shoes (well, some dogs do slippers) because they don’t, for instance, offer much useful protection against dropping a really heavy box, edge-on, on your foot. Gloves are another case in point.

[mattheus]

They also mention, perhaps in print too small, that a cycling helmet will do nothing for you in a crash with a car or if you go over a cliff (even a small one) to hit your head on the rocks below at a large velocity

This is one of the points that always baffles me when it’s put forward in The Great Helmet Controversy.

There have been many discussions on the GHC. Is it likely that your bafflement will be cured during this episode?? Tell us what you want us to say to de-baffle you!

[roubaixtuesday]

re bafflement and the Great Helmet Controversy, it reminds me of Sayre's Law

"Academic politics is the most vicious and bitter form of politics, because the stakes are so low."

The one thing research on helmets does show us is that they don't make much difference one way or the other - it really doesn't matter much whether people wear them or not.

Hence the vicious and bitter debate.

[pjclinch]

They also mention, perhaps in print too small, that a cycling helmet will do nothing for you in a crash with a car or if you go over a cliff (even a small one) to hit your head on the rocks below at a large velocity

This is one of the points that always baffles me when it’s put forward in The Great Helmet Controversy. Put bluntly: I think it’s incorrect/misleading.

One of the things often reported about incidents where a helmet comes into play at above its tested rating is that the helmet gets damaged/broken/smashed. Achieving that requires energy, so the energy dissipated in damaging the helmet is energy that isn’t dissipated in busting the head, or some other part of the anatomy.

Final brittle fracture is part of the energy take-up. It's a relatively small part, but it is a part.
But I'd say the far more misleading thing is assuming any collision with a car will surely overwhelm a helmet, because collisions with cars can vary between getting nudged off sideways (where all the car really does is tip your balance but doesn't transfer great amounts of energy) to a full on collision at high speed with something like a door pillar (which, unlike something like the bonnet isn't going to deform much).

Another popular misconception is that as helmets are only tested/specced for low speed falls they can't be any use at speed, but typically horizontal speed is scrubbed off relatively slowly so tends not to break skulls (obviously not the case if you hit a wall head on), while vertical speed tends to be purely from gravity and unless it's an unusually high bike tends not to vary that much from the design spec.

Now, that difference in energy transferred to the head may or may not be decisive. Probably not in the “over a cliff onto the rocks below” scenario, where the total energy involved at the point of impact is likely to be so great that all sorts of horrible injuries to all sorts of bits of the anatomy will result. But, there must be a range of impact energies where subtracting the energy needed to damage a helmet from that transferred to the anatomy is useful.

While it's a feasible mechanism It's proven remarkably hard to demonstrate that significant numbers of fatal crashes have been turned in to "merely" serious ones, or serious in to minor, but again that's not the same thing as useless. The original design goal of the expanded polystyrene lid was a "better hairnet", and I don't think anyone much wore a hairnet expecting it to save their lives. What would be a more realistic hope would be having had an off there'd be a better chance of getting back on and finishing one's race (I don't think I've seen a hairnet outside of a sporting context) rather than seeing stars and abandoning. Not that this doesn't apply to e.g. commute cycling, but if I was falling off my bike on a commute as much as, say, bunch sprinters in flat Grand Tour stages I'd want to look at causes at falls more than mitigating their effects on a small part of me. As it is, even with plenty of off-road falls the last time I managed to hit my head coming off was about 20 years back (daydreaming in the Brompton, a particularly savage speed-bump had me over the bars), and the helmet I had didn't help because I took it on the chin.

Shoes are another form of PPE where this sort of thing applies. They offer complete protection to the feet in many minor, low energy unintended impacts, and/or unintended impacts in common directions, but incomplete protection, decreasing to ‘none worth considering’, as the energy levels go up, and the direction of forces, and/or force per unit area change. And, we pretty much all wear shoes for most of the time; we don’t eschew shoes (well, some dogs do slippers) because they don’t, for instance, offer much useful protection against dropping a really heavy box, edge-on, on your foot. Gloves are another case in point.

Yes, particularly gardening gloves. Takes the worst out of bramble thorns, not much use against a chain saw.
Shoes are an interesting one... if you look at barefoot populations (e.g., rural Africa/India) it turns out that folk in shoes tend to get ankle injuries at a much higher rate than those without. Unintended consequences of "protection"...

Pete.

[Nearholmer]

Tell us what you want us to say to de-baffle you!

Probably no point.

What I want to know isn’t knowable given the present and foreseeable state of evidence-based knowledge, so if I asked the questions (again) all they would do would provoke a flurry of opinion, argument, and possibly even people insulting one another (again).

[Cowsham]

The one thing research on helmets does show us is that they don't make much difference one way or the other - it really doesn't matter much whether people wear them or not.

While I can agree with pjclinch on the point about helmets having varying degrees of benefit wrt head protection I don't think I can agree with this statement.

ie there are plenty of studies that show there is some benefit.

[roubaixtuesday]

The one thing research on helmets does show us is that they don't make much difference one way or the other - it really doesn't matter much whether people wear them or not.

While I can agree with pjclinch on the point about helmets having varying degrees of benefit wrt head protection I don't think I can agree with this statement.

ie there are plenty of studies that show there is some benefit.

No studies show they make a big difference, and most seem to show benefits too small to quantify. ie it doesn't matter very much.

If there were a big difference, it would be immediately evident across all studies. It isn't.

[Cowsham]

The one thing research on helmets does show us is that they don't make much difference one way or the other - it really doesn't matter much whether people wear them or not.

While I can agree with pjclinch on the point about helmets having varying degrees of benefit wrt head protection I don't think I can agree with this statement.

ie there are plenty of studies that show there is some benefit.

No studies show they make a big difference, and most seem to show benefits too small to quantify. ie it doesn't matter very much.

If there were a big difference, it would be immediately evident across all studies. It isn't.

I didn't say 'big difference' I said 'some benefit '

[mattheus]

Tell us what you want us to say to de-baffle you!

Probably no point.

What I want to know isn’t knowable given the present and foreseeable state of evidence-based knowledge, so if I asked the questions (again) all they would do would provoke a flurry of opinion, argument, and possibly even people insulting one another (again).

Very wise!

[pjclinch]

The one thing research on helmets does show us is that they don't make much difference one way or the other - it really doesn't matter much whether people wear them or not.

While I can agree with pjclinch on the point about helmets having varying degrees of benefit wrt head protection I don't think I can agree with this statement.

ie there are plenty of studies that show there is some benefit.

No studies show they make a big difference, and most seem to show benefits too small to quantify. ie it doesn't matter very much.

If there were a big difference, it would be immediately evident across all studies. It isn't.

And here we need to be careful with the language and realise that a study doesn't typically show, it reports.
To show something you typically want a series of repeated experiments using the same methodology confirming the same thing, and while we have lots of studies that report a big effect (e.g., the infamous 85/88% reduction in nasties from Thompson, Rivara and Thompson) what we don't have is consistent effects from an agreed good methodology.

There needs to be a better understanding that a study published in a peer reviewed journal isn't the end of the story (or we'd all be running our homes from cold fusion jam-jar reactors by now), it's part of the overall picture that will (hopefully) work towards a consensus, but in the particular field of cycle helmet efficacy there's nothing like consensus, so picking the ones you like the look of isn't a safe strategy to get the truth.

Pete.

[pjclinch]

While I can agree with pjclinch on the point about helmets having varying degrees of benefit wrt head protection I don't think I can agree with this statement.

ie there are plenty of studies that show there is some benefit.

No studies show they make a big difference, and most seem to show benefits too small to quantify. ie it doesn't matter very much.

If there were a big difference, it would be immediately evident across all studies. It isn't.

I didn't say 'big difference' I said 'some benefit '

But the point you were disagreeing with did say "big difference".
Compeed is of "some benefit" in preventing blister injuries (which can be painful and debilitating), but I doubt it keeps that many people out of A&E. It's entirely possible to have something that's of "some benefit" to injury prevention but that makes little difference to the need for specialist medical emergency care and gross safety.

Beyond that you still seem to be having trouble grasping that being better off if in some situations if you hit your head isn't the same thing as overall cycling safety.

Pete.

[roubaixtuesday]

While I can agree with pjclinch on the point about helmets having varying degrees of benefit wrt head protection I don't think I can agree with this statement.

ie there are plenty of studies that show there is some benefit.

No studies show they make a big difference, and most seem to show benefits too small to quantify. ie it doesn't matter very much.

If there were a big difference, it would be immediately evident across all studies. It isn't.

I didn't say 'big difference' I said 'some benefit '

If the "some benefit" is so small it doesn't even show up in most studies, then we can safely conclude the benefit isn't significant. Hence my "don't make much difference one way or the other" which you seem to disagree with - note the emboldened.

Your opinions on this seems extremely strong given how small the benefits are shown to be, hence analogous to "Academic politics is the most vicious and bitter form of politics, because the stakes are so low."