Cyclists hitting their heads on crashing

[mjr]

What it might do, and I’m not sure there’s truly solid evidence either way, is cause you to act more recklessly, increasing the probability of a crash in the first place.

At least in the case I'm most concerned about (me!), I'm pretty convinced it did, at least for the last crash: I wouldn't have ridden on a day with a risk of ice without it. I realised my error and got studded tyres after that.

But I don't see an obvious way it caused me to act in a way that made head impacts more likely than other types of crash.

[mattheus]

What it might do, and I’m not sure there’s truly solid evidence either way, is cause you to act more recklessly, increasing the probability of a crash in the first place.

At least in the case I'm most concerned about (me!), I'm pretty convinced it did, at least for the last crash: I wouldn't have ridden on a day with a risk of ice without it. I realised my error and got studded tyres after that.

But I don't see an obvious way it caused me to act in a way that made head impacts more likely than other types of crash.

Ah, I think I see now; you mean like choosing trails with lots of low-hanging branches, that sort of behaviour?

[Nearholmer]

Interestingly, or more to the point foolishly, my minor head bang on ice before Christmas was very similar in (flawed) thinking to MJR’s case.

I was on the shopping bike, on which I usually don’t wear a helmet, but I knew it was icy, so put a helmet on and went.

What I should have done was not to have gone at all, and if there wasn’t a helmet on the coat hook by the door, I probably wouldn’t have.

[mattheus]

Yes, but I don’t for one moment believe that wearing a helmet causes one to act differently, to not instinctively protect the head, in a crash. If you are going forward, your hands go out whether or not you’ve got a hat on.

First things first: I'm far from sure that there will be a measurable effect of this nature. (Just as there doesn't seem to be measurable protection from cycle helmets at population level.)

But i'd struggle to completely rule it out. Because for one thing, there are plenty of examples in sport where behaviours have measurably changed. (the biggest data set being from putting face-guards on American Football helmets - it significantly increase brain injuries).
Cricket and boxing would also be good activities to study.

[Stevek76]

My 'dozing off' was perhaps a little flippantly worded but reaction times are faster with increased alertness and in my experience that tends to be maintained far more easily on short transport trips and off roading than lengthy road rides.

You don't need to be expecting a specific incident to react faster, general alertness also factors.

Reaction times eye to hand is typically 250ms, age does affect it but so does practice, well used neural pathways react quicker than unused ones. Those who frequent the rowdier side of cycling tend to be better at falling off safely simply out of practice. Likely a bigger reason than age as to why younger relatives win at reaction based card/video games in my view, they don't just play them at Christmas!

Reaction time from feel is actually much faster though, perhaps as much as half that of by sight and I'd think that's the more relevant one here.

Re crash rates, pedestrians are probably the better comparator as they are broadly in the same risk ballpark as cyclists. Though pedestrian numbers are probably a bigger underestimate due to the quirks of what is counted as a transport casualty. If you're cycling on the road and crash without other parties you're eligible to be included in the statistics. If you trip and fall as a pedestrian you are not. Nor if you ran into another pedestrian; at least one vehicle must be involved.

[Steady rider]

http://www.cycle-helmets.com/helmet_damage.html
The paper provided calculations based on a forward motion and relative forces for helmeted and non-helmeted.
Typically a person falling sideways may move their head away from the ground, in trying to avoid contact. A helmet may be about 20-25mm on the side thickness. The cyclists falling seem to take most of the impact on their shoulders, arms, with the helmet impacting later.

Research on the impact location on helmets shows most impacts occur to the sides. Depending on the forward speed when falling this could affect the level of rotational acceleration to the brain. By not wearing a helmet, a cyclist would be more likely to avoid an impact to the head part of their body in a sliding type of fall.

The old video showing cyclists falling on ice, probably had about 20 falls, without one hitting their head. The link below seems a new version, not as close up as the old one.

https://www.youtube.com/watch?v=VxWpwWByPfI

old video reported https://road.cc/content/news/28708-dutc ... aths-video

[tim-b]

Thanks
I don't have your engineering background, so be patient with me.
I can't see in the paper ^^ where the mass of the helmet used to determine additional forces is stated. I can only see "mass" in relation to fatigue and OTB. I'm also unclear about how the effective diameter of 250mm is measured.
I'd guess that helmet dimensions have moved on since 2007, I think that I'd struggle to find a properly-fitting helmet with "a helmet thickness (that) could be up to about 60mm". Your 30mm figure may be nearer

The paper seems to be about rotational forces on contact with the ground rather than the mass of the helmet contributing to the helmet/head striking the ground in the first place; in reality surely one force leads to the other?
Manufacturer's figures, my helmet weighs 243g (+/-10g) and £16.99 to buy, so nothing special. Clearly the helmet will increase the force of any strike and increase rotational force, but the outcome is of more interest to me.
Are any injuries increased or reduced taking into account the harder, shiny outer shell that reduces the friction producing part of the rotational force and the protective element of the foam?

The video of slow-moving commuters on upright bikes and padded in thick coats doesn't apply to me at one end of the scale and neither does the full-on pro-rider at the other, although clothing, helmet, bicycle type and (downhill) speed is more similar

[pjclinch]

I don't have your engineering background, so be patient with me.

Part of the overall problem is that taking a purely engineering approach (typically from people taking an angle they know) to an issue that also involves a lot of behavioural psychology misses a lot of the stuff that will determine whether a helmet is a good idea, a bad idea, some mix of the two where it's hard to see which is more important over the whole range of a rider's different activities/contexts, or simply irrelevant.

It's also the case the total range of possible impacts, while not infinite, is certainly a very big number and far more than it's easy to model. This is why the standards used just tell you what is measured, rather than whether they amount to safer.

Are any injuries increased or reduced taking into account the harder, shiny outer shell that reduces the friction producing part of the rotational force and the protective element of the foam?

I would wager that the answer to that question is... "it depends". Typically on the exact geometry of impact and all surfaces involved (both of which are inherently very complicated because people have so many moving parts and crashes happen for all sorts of reasons in all sorts of places)

People have been trying to come up with a smoking gun on this for over 30 years. Nobody has, despite occasional claims (typically from Jake Olivier) that it's been cracked once and for all. And if nobody has really come up with a hard answer after 30 years of hard effort it is unlikely that the relatively unskilled musings of our good selves will get any closer (though just as anyone can criticise a film even if we can't make our own, that doesn't mean we can't point out issues with the work).

The real helmet debate, almost as much for individuals as populations, isn't so much "are they good or bad?" but "how much do we really know about their effects and performance in the wild?". I would suggest that, despite disappearing down measurement and calculation rabbit holes, the answer is "less than we'd like". In the meantime, if you're happier in a lid, wear one, and if you're happier without then don't. Sweating it will just make you sweat, not give you a definitive answer.

Pete.

[Steady rider]

My impression is a few general points may apply.
Most head injuries to cyclists are mild and severe head injuries infrequent. Concussions are one main type.
Helmets appear to reduce skull fractures but not concussions, that are perhaps 3 times higher in number.
A 2022 conference paper reported.
From 50 years of cycling the average person could incur about a 1% risk of being admitted for a serious head injury (including face) or about a 0.025% fatality risk.

Cycling UK report,

Some evidence suggests they may in fact increase the risk of cyclists having falls or collisions in the first place, or suffering neck injuries.

Tim-b asked

Are any injuries increased or reduced taking into account the harder, shiny outer shell that reduces the friction producing part of the rotational force and the protective element of the foam?

It seems fractures may reduce but not concussions. The friction of hair is generally lower than plastics and skin removal on impact may also help protect from brain rotation but leave a nasty head wound.

Over years of helmet wearing, extra wear to the neck, may cause additional problems.(head mass + 5% for helmet+ potentially more impacts).

Balancing the evidence, some protection is possible but may be relatively infrequent, more likely are extra impact occurring to helmets and perhaps extra accidents. It is worth bearing in mind the health benefits of cycling may be many times higher than the risks, so that the important aspects is that helmet promotion or requirements do not act to discourage cycling. https://www.cyclinguk.org/briefing/cycle-helmets

[foxyrider]

A bit late to this thread but its been quite fascinating.

My personal experience from some 45 years of riding is that a helmet would have made no difference to my injuries the couple of times i have had head injuries in cycling incidents. How do i know? well each time, one a convoluted ice fall and the other an over the bars ice induced crash, resulted in lower face scrapes, which of course only a full face helmet might prevent. Of the other falls, none resulted in any head / ground impact - even when i tried flying using a sunken man hole cover as a ramp, i travelled some 10m, put my shoulder out and got a few bizarre cuts and scrapes but nothing on my head.

I don't generally wear a helmet, only when event participation makes it compulsory or mountain biking where i consider there is a higher risk of hitting something (not that i've ever had more than a few abrasions from mtb offs). I'll also admit to having done some judo as a child I have, like others have commented, banged my head many times where riding a bicycle wasn't involved resulting in all sorts of lumps, bumps and contusions - a lot have been me walking into things, cupboard doors, signs, bus mirrors (a regular occurence at one time ), low doorways / ceilings, bikes in workstands / displays and even a trike falling off a shelf (i used to work in a bike shop) as well as falls / trips / rugby etc, etc.

I'm sure some people will take more chances when wearing a helmet in much the same way that they do with 'better' brakes but what impact (sic) that has on injury / accident statistics will never be known - who would admit it even if they were aware?

[tim-b]

Thanks all.
I always wear a helmet when I know that loose/slippery/rocky/rooty surfaces abound. I had a bit of a helmet "moment" yesterday as I ducked under a part-fallen branch and thought, "will my helmet clear it?". It did, but I think that after 60 years experience I have a better idea of where my scalp is than I do an additional lump of foam

[mattheus]

The video of slow-moving commuters on upright bikes and padded in thick coats doesn't apply to me at one end of the scale and neither does the full-on pro-rider at the other, although clothing, helmet, bicycle type and (downhill) speed is more similar

Why not? Do you never take a tight slow corner? Never encounter slippery surfaces?

[tim-b]

Why not? Do you never take a tight slow corner? Never encounter slippery surfaces?

I don't own an upright bike with flat pedals (you can see riders putting their feet down) and I don't cycle in heavily padded clothing, both of which change the mechanism of the impact and the likelihood of a head impact as compared to other styles of clothing and bike

[pjclinch]

Why not? Do you never take a tight slow corner? Never encounter slippery surfaces?

I don't own an upright bike with flat pedals (you can see riders putting their feet down) and I don't cycle in heavily padded clothing, both of which change the mechanism of the impact and the likelihood of a head impact as compared to other styles of clothing and bike

I suspect you are quite far in to rationalisation territory here.
Do you think your average Dutch winter commute involves looking the Michelin Man? Have you access to a copper-bottomed biomechanical assessment of head impact likelihood using pedals one unclips from against those where you don't?

As I said before, there's nothing really wrong with just doing what your gut is happier doing, but trying to convince yourself that e.g. you should be wearing a crash helmet because you're not wearing a thick jacket really isn't a great idea. Everybody rationalises, it's all part of being human, but realising when you are and admitting to yourself you're making pretty vague, arm-wavey assumptions is important..

Pete.

[Cugel]

As I said before, there's nothing really wrong with just doing what your gut is happier doing, but trying to convince yourself that e.g. you should be wearing a crash helmet because you're not wearing a thick jacket really isn't a great idea. Everybody rationalises, it's all part of being human, but realising when you are and admitting to yourself you're making pretty vague, arm-wavey assumptions is important..

Pete.

Hee hee hee, quite so.

On the other hand .... there are rationalisations and rationalisations. Some are actually reasonable whilst others are convoluted or well-chopped logic-no-more missing some essential ingredients (the absent yet relevant propositions).

It is possible to differentiate various risk factors and their likelihood of realising in various different circumstances. The calculations may be more or less precise, depending on how complex is the situation being risk-assessed. The desire to avoid the possibility of the consequences of a risk realising might vary with the severity of the possible consequences and the degree to which the risk assessor feels they want to avoid those consequences.

Personally I try to do this with bicycle helmet wearing. My "calculations", crude though they are, mean I don't see the risks of not wearing one (badly banging my head on something) as at all likely to realise; or the consequences of the risk (of falling on my head from a bike) realising likely to be significantly reduced by wearing a flimsy bicycle helmet.

The basis of this calculation is that I've never fallen off a bike in 63 years of riding one and banged my head; that every fall I have had from a bike has banged lots of bits but never my head; that a bike helmet (according the the makers) will not protect against seriously damaging head blows; that comparison of dozens of other activities I perform have a much greater risk of head bang yet I've never needed or worn a bike helmet for those either and neither has anyone else.

**************
So, it's not just "a pretty vague, arm waving assumption" but a decision based on a degree of (I will claim) cogent rationalising. And, should some personal circumstance change (perhaps even just getting older and less in control of the old body) I'll recalculate the risk, perhaps with a different outcome in choosing risk reduction behaviours. (More likely, stop riding a bike than start wearing a pretty ineffective helmet).

Cugel