BBC programme in the Sliced Bread series: "Cycle Helmets"

[Pete Owens]

That applies to all utility cycling - not just hire bikes.

[Nearholmer]

It does, even to me as a person who wears one when ‘cycling’, but often doesn’t for utility trips, and it seems to doubly apply to hirers.

I’m back in south London next week, so if I get an idle half hour in a corner cafe, I will try to get a numeric sample.

[Jdsk]

...
Trouble is, evidence based research (this programme isn't it would appear) is not easy sometimes to evaluate. So much out there is loaded to present a certain view. Cycle helmets are not unique. Try doing a Medline search for chronic fatigue syndrome and you will see what I mean. Truly a nightmare.

Evidence based methods are a major defence against a whole range of different biasses, including ad hominem argument and selection bias.

I don't understand how doing a Medline search would throw any light on anything except how much stuff gets published that doesn't meet evidence-based criteria.

Jonathan

[Jdsk]

And if the inclusion and exclusion criteria tilted the table, yet the review was published anyway and people are basing decisions about the general population on an unrepresentative subset, what would you do?

I don't know what you mean by "tilted the table" but the point about doing it systematically and, nowadays, using one of the agreed templates is that anyone can check your working.

Tilting, aka nudging, is manipulating the game in order to get the result you want. See https://en.wikipedia.org/wiki/Pinball#Nudging

In this context, it would be setting the selection criteria in the way believed most likely to support one's prior belief.

Say you check the working and believe this has happened. What do you do?

And if the review conclusion's supporters say the exclusion of people like you (freewheeling utility riders) is reasonable, but the conclusion or its consequences should still apply to you?

First I recommend reading pjclinch's earlier response to this.

But i'd like to use this to open up a separate point: the importance of separating the process of finding out what we know and we don't know from any decisions about what to do, whether as an individual or in national policy.

There are many other steps after review of the evidence that should be followed, including level of evidence, ethical considerations and external validity, as you say, does it apply to me/ this particular group etc. Of course there are now good protocols for checking that these steps aren't omitted.

Jonathan

[Jdsk]

most people do wear cycle helmets

Do they?

I’d be interested to see reliable data.

My unreliable observation is that “most”, being more than half, might be an overestimate. Lots do, but lots don’t.

My unreliable observation is that everyone I see apart from spotty youth, pub man and drug dealer do wear helmets. Indeed, you get questions if your not wearing a helmet, but I suppose it varies from place to place.

I am not familiar in any way with the data on wearing. None of the following has been found systematically and much better information might be available. I make no claims about any of the organisations.

https://www.roadsafetyknowledgecentre.org.uk/rskc-385/
https://trl.co.uk/uploads/trl/documents/TRL286.pdf
https://trl.co.uk/uploads/trl/documents ... Review.pdf
... there's a TRL series but i don't know the date of the most recent report.

https://www.headway.org.uk/media/3407/t ... y-2014.pdf

https://www.dekra.com/en/bicycle-helmet ... -capitals/

Jonathan

[Stevek76]

The only truly reliable way to get info on helmet use would be via household travel surveys, they are the gold standard (if the sampling methodology is solid) for representative pictures on travel behaviour as the issue with any point location count is you are immediately biasing to that location. As noted, this is not a question covered by the DfT's NTS.

It does, even to me as a person who wears one when ‘cycling’, but often doesn’t for utility trips, and it seems to doubly apply to hirers.

Very much so, there are people who query my lack of helmet use and use one on a bike but will happily hop on a rental escooter for the odd trip without one!

[harriedgary]

risk compensation ~
over the last 20 years or so, violent "video" games a.k.a computer games have proliferated worldwide. And despite age restrictions, I'd suspect that many a teenager has played or at least seen others playing a game involving one person graphically kill another person using bats, knifes, swords, guns, explosives or poetry recitals.

Is the recent surge in knife crime in the UK due at all to a dulling and false perception of the dangers of knife crime and injuries, or in reality is it just situation normal for the gangs and disaffected youth of today. I mean, are kids stabbing other kids because they think they'll just get another life after a quick trip to A&E. I read a few court reports where the accused or convicted said words to the effect "I didn't intend to kill him, just frighten him and mess him up a bit" Even though those of us of a certain age knew from playing soldiers, that shooting was for killing the enemy from a distance, and knifing was to silently dispatch them from close up.

So, helmets. Yes, I've almost forgotten the point I was gonna make
If car drivers see a cyclist wearing the "regulation" helmet, will their risk compensation thought process be something like "oh they have a helmet, they will be OK if I accidentally do knock them off" Vs "Gott im Himmel if I knock that cyclist off, they might die, I better leave safe room for them" I'm sure this argument has been poached and simmered many times before, like the corresponding argument that the cyclist themselves might take more risk wearing a helmet.
I know if I foresee a hit the dirt moment coming, then I focus hard on protect my hands, and protect my head. And knowing that a helmet offers little protection against an actual collision with hard object by heavy head moving at 10 metres per second, I don't think wearing any helmet would improve my chances. After all, BMX riders wear much beefier models than any road cyclist does, more like motorcycle helmets.

[mattheus]

Thankyou, caller.

[Nearholmer]

an actual collision with hard object by heavy head moving at 10 metres per second, I don't think wearing any helmet would improve my chances.

Which I’m not at all sure is a useful way of deciding whether or not to wear a helmet.

It can be perfectly rational to choose to wear a helmet when cycling because it offers good protection against certain sorts of impacts, and because it offers some, incomplete, protection against other sorts of impacts.

By no means all impacts to the head as a result of cycling accidents are “full on perpendicular”, and by no means all occur at relatively high speeds or energies. There are oodles of ways of falling off a bike, or getting hit by something while you are still on it, and oodles of possible “contact modes”, so the poor old brain can experience a multiplicity of different input energies and rates of deceleration under different scenarios.

I would suggest that, if there were absolutely no disadvantages to wearing a helmet, it would be irrational not to wear one, because it might one day provide complete or partial protection.

But, since there seem to be some potential disadvantages in wearing a helmet, things like possible adverse affect on balance, the theoretical possibility of risk over-compensation by the wearer, possible risk compensation by vehicle drivers, possible increase in rotational injury to the head with some helmets in some impact scenarios, etc, then it becomes a case of weighing those those against the potential protection it might provide.

So, we have plenty of things to put in the scales on either side. Trouble is, and despite enough technical and statistical papers to stretch to the moon, we don’t know the weights of any of these things with any certainty, so we have to proceed on the basis of our individual assessments: taking all we know about this stuff, and our personal ‘cycling profile’, do we think that on balance it’s best for each of us individually to wear a helmet, or not?

Which means that none of this is “black and white” at the individual level of people who have already committed to cycle.

When we then “zoom out” to a societal level, a whole heap of other considerations come into play, particularly around people who haven’t yet committed to cycle, and what affect anything ranging from compulsion to information provision might have on them.

Where I think the debate sometimes goes badly off the rails is: when some individuals attempt to persuade the rest, sometimes to the extent of “ramming down others throats”, that their personal assessment should become the template for all; when the questions that apply at an individual level and the questions that apply at a societal level get all tangled up together; or, when people look at the thing from too few perspectives.

[pjclinch]

And knowing that a helmet offers little protection against an actual collision with hard object by heavy head moving at 10 metres per second, I don't think wearing any helmet would improve my chances.

Depends partly on what you mean by "your chances" and also not so much on how fast you're going but how fast you stop.

Look at this, and ask yourself if racing leathers are rated to protect at this sort of speed...
https://www.youtube.com/watch?v=kZZTapcPRSk&t=37s

Because he kept most of his energy when he fell and scrubbed it off relatively slowly he got away with it, and with some style. Had he hit a wall at that speed he'd quite probably have smashed his body well beyond jogging away.

Similarly, a cycle helmet can do a useful job at speeds well over the oft-quoted 12 mph as long as the rider keeps going (which they often will if the hard object is a horizontal(ish) road), because it's not how much kinetic energy you have when you hit that matters so much as how much you lose very, very quickly.

As for "your chances", the sort of energy you lose in a hurry from gravity, whatever your horizontal speed, is the sort of energy that can kill but typically doesn't: it's not that different in terms of bone-breaking energy to tripping over walking. So the helmet might typically save you gravel rash and a very, very bad headache. It could do a useful job without much affecting your chances of death.

Pete.

[Jdsk]

...
So, we have plenty of things to put in the scales on either side. Trouble is, and despite enough technical and statistical papers to stretch to the moon, we don’t know the weights of any of these things with any certainty, so we have to proceed on the basis of our individual assessments: taking all we know about this stuff, and our personal ‘cycling profile’, do we think that on balance it’s best for each of us individually to wear a helmet, or not?

Which means that none of this is “black and white” at the individual level of people who have already committed to cycle.

When we then “zoom out” to a societal level, a whole heap of other considerations come into play, particularly around people who haven’t yet committed to cycle, and what affect anything ranging from compulsion to information provision might have on them.

Where I think the debate sometimes goes badly off the rails is: when some individuals attempt to persuade the rest, sometimes to the extent of “ramming down others throats”, that their personal assessment should become the template for all; when the questions that apply at an individual level and the questions that apply at a societal level get all tangled up together; or, when people look at the thing from too few perspectives.

This is a very good description of the best approach to making the several different decisions that have to be made.

And we could escape much of the morass into which this forum descends by separating out the different questions and explicitly discussing the principles of how to make the decisions.

Thankyou for posting it.

Jonathan

[colin54]

Yes, nicely put Nearholmer; though I've never heard about helmet wearing affecting balance before.
I'm afraid the discussions about statistical methodology etc (if that's the correct phrase), are beyond me.
I feel we're fortunate to still have freedom of choice anyway.

[pjclinch]

Yes, nicely put Nearholmer; though I've never heard about helmet wearing affecting balance before.

Steady Rider has expressed concern about the balance effects of helmets: they're extra weight and windage so there will be extra forces in play... but as to whether these are significant I'm not at all convinced.

As a slaphead my head is lighter and more aerodynamic than someone with lots of hair (an elaborate hairstyle will weigh on the order of the same as a lid, according to a quick Google search), so does that make me safer in terms of crashes? If it does, should we put out warnings for people with Big Hair on their increased risk when cycling? Sikh men, with a lot of hair and generally held in a wind-catching turban... Are they having more accidents? Perhaps we should do a study comparing accident rates of otherwise similar Sikh/non-Sikh communities to check this? (or perhaps not...)

It's possible, but in practice my (observational, un-measured) feeling is that the extra loads imposed by helmets are easily within the realms of forces that can be compensated for (which is how trick riders like Danny MacAskill or freestyle BMX champions can perform amazing feats of balance), and while there is a theoretical line between over-the-bars disaster and staying on the bike that can be tipped with anything extra my feeling is in practice that riders tend to have events well one side of it or the other: if you unintentionally do a perfect stoppie without a helmet on then a helmet might have pushed you over... but how often do riders do perfect on-the-line stoppies? My feeling is you're either in no-chance territory or you're not going over the bars anyway.
As I've also suggested, if we need to worry about helmets pushing us in to crashes because of their (low) weight and wind effects, where does that leave us with rucksacks? Or the balance effects of on-bike luggage, which tourers and shoppers will know affects handling of the bike quite noticeably. Or with something like drop bars, where an aero crouch puts the weight further forward (so easier to go over the bars), makes the bike faster (so easier to crash) and also tends to act against the rider looking where they're going compared to more upright viewpoints.

While you can calculate forces and accelerations that a lid will add it's going to be incredibly hard to demonstrate any causative effect on disasters because it's a small effect (or no Danny MacAskill) and there is going to be so much noise in any data: in my experience how much my mind is wandering, or how tired I am, or if I got out of bed the wrong side etc. will have a far more noticeable effect on how well I ride than what I'm wearing. And so on.

Thus I am inclined to put this in the "we have more pressing things to worry about that we are sure have an effect on real safety" box.

Pete.

[Nearholmer]

^^^
My view is exactly the same, and I only included it in the list of possible factors to avoid accusation of leaving things out.

[Jdsk]

As above.

But unfortunately it is more serious than that because the unevidenced assertions about effects on balance have been used to try to influence the discussion. Here's a recent example:
viewtopic.php?p=1764123#p1764123

A couple of simple questions revealed that there was no answer to what "the force" was or where it was acting.

Jonathan (or Luke)