Why I don't wear a bike helmet.

[SteveH]

Yes, bike helmets again. This article gives the reasons far better than I can. If you think I'm wrong, and should wear a helmet, please answer the points in this article with reliable statistics and arguments.

The link again, for clarity:
http://www.howiechong.com/journal/2014/2/bike-helmets

[bluehillside Retd.]

What article?

[Nearly Sane]

What article?

Click on the 'This' at start of 2nd sentence

[bluehillside Retd.]

Thanks NS

[bluehillside Retd.]

Steve H,

The article is a mess.

1. He begins by acknowledging that, “if you get into a serious accident, wearing a helmet will probably save your life. According to a 1989 study in the New England Journal of Medicine, riders with helmets had an 85% reduction in their risk of head injury and an 88% reduction in their risk of brain injury. That’s an overwhelming number that’s backed up study after study. Nearly every study of hospital admission rates, helmeted cyclists are far less likely to receive serious head and brain injuries.”

So far, so good then

2. Next though he talks at some length about the incidence of head and neck injuries in other modes of transport being at equivalent levels to those for cycling but it would be unacceptable to promote helmets in, say, cars. Well yes, but so what? That’s called an argument from irrelevance – “we get injured when travelling in other ways, so we shouldn’t protect ourselves when travelling on bikes”. It’s like arguing that when there are six bullies in the playground that you can’t take out you shouldn’t deal with the one you can take out. It’s nonsense – not being able to protect people from head injuries in every form of transport isn’t an argument for not protecting people in one form of transport.

3. Then he turns to “how bike helmets may be harmful”. He continues: “In 2001, an article in the New York Times reported that the rate of bicycle head injuries had risen sharply — an increase of 51% — during a ten-year period when bicycle helmet use became widespread. This during a time when statistics showed an overall decrease in bicycling in the United States. No one knows for sure why head injuries among cyclists increased, but there are a few theories”. Note that “No one knows for sure why head injuries among cyclists increased”. Nor therefore do they know what the increase might have been had helmet-wearing not become more common. You’d need a comparable study to find that out, and absent that he seems to have fallen for a classic correlation = causation inference.

4. Note too that “This during a time when statistics showed an overall decrease in bicycling in the United States”, about which the NYT article says “During the same period, overall bicycle use has declined about 21 percent as participation in in-line skating, skateboarding and other sports has increased, according to the National Sporting Goods Association…” What does that mean? That the number of cyclists has declined by 21%, or that the number of miles ridden has declined by 21%? They’re very different things – and it would be the latter that matters here, not the former. A decrease in miles ridden is a decrease in opportunities for an accident; a decrease in the number of cyclists is neither here nor there.

5. Finally, note too this from the NYT article: “Dr. Richard A. Schieber, a childhood injury prevention specialist at the Centers for Disease Control and Prevention and the leader of a national bicycle safety initiative, said public health officials were realizing that in addition to promoting helmet use, safety officials must teach good riding skills, promote good driving practices and create safer places for people to ride. ''We have moved the conversation from bicycle helmet use to bicycle safety,'' Dr. Schieber said. ''Thank God that the public health world is understanding there is more to bicycle safety than helmets.''

He says explicitly, “in addition to promoting helmet use”, not instead of promoting helmet use. That’s the point – not to discourage helmet wearing (especially given their life-saving effect (see para 1)), but to encourage their use responsibly by teaching people not to take more risks when using them. He also says, "Thank God that the public health world is understanding there is more to bicycle safety than helmets" which is fair enough, but certainly does not mean that cyclists should not wear helmets.

6. Short version - there's just one measure that matters: given two sample groups with identical miles ridden in identical conditions, which would record the lower incidence of brain injuries: the group wearing helmets, or the group not wearing helmets?   
   

[ad_orientem]

I don't wear a helmet mainly because I don't want to look like one.

[bluehillside Retd.]

ad,

I don't wear a helmet mainly because I don't want to look like one.

Why do you think that's a good enough reason?

[ad_orientem]

ad,

Why do you think that's a good enough reason?

It's good enough for me.

[bluehillside Retd.]

ad,

It's good enough for me.

Fair enough. It's your choice. 

[BeRational]

I don't wear a helmet mainly because I don't want to look like one.

But you do by not wearing one.

[SteveH]

Risk homeostasis means that riders with helmets are likely to take more risks and ride faster because they think they're safer. Therefore, they are more likely to have accidents in the first place.
It is a well-attested fact that car drivers tend to give a wider berth to helmet-less cyclists than to helmeted ones, which also increases the likelihood of helmeted wearers having accidents.
Head injuries to cyclists are in any case very rare (ordinary road cyclists, that is - off-road mountain biking is another matter), even in quite serious accidents. In accidents, riders generally fall over to one side, injring their arm and leg on that side, but not their head. Even when they go over the handlebars, they usually stick their arms out in front of them and don't hit their head.
Helmets project out from the head up to two inches, so the fact that a helmet is smashed doesn't necessarily mean that the cyclist's head would have been. There is some evidence that this fact means that helmets can cause serious neck injuries.
I think all of these facts are mentioned in the article, but BHS and BR avoid addressing them.
BHS cxan talk about the fallacy of irrelevance, but it remains true that car users suffer considerably more head injuries than cyclists proportionally to their numbers, but no-one is nagging them into wearing helmets.

[ad_orientem]

But you do by not wearing one.

Eh? In bizarro world maybe.

[bluehillside Retd.]

Steve H,

Not sure why you’ve just ignored my rebuttal of the article in favour of repeating the mistakes it makes, but briefly…

Risk homeostasis means that riders with helmets are likely to take more risks and ride faster because they think they're safer. Therefore, they are more likely to have accidents in the first place.

As are drivers wearing seatbelts, or driving cars with airbags and ABS brakes. Yet we either mandate these things (seatbelts) or increasingly design them in to cars. Why? Because, even when drivers using safety devices take more risks, the net effect is still fewer deaths and injuries. It’s long been known that, for example, airbags should have a greater positive effect than they do, but drivers are still safer with them than not. 

It is a well-attested fact that car drivers tend to give a wider berth to helmet-less cyclists than to helmeted ones, which also increases the likelihood of helmeted wearers having accidents.

See above. Take two matched groups of cyclists and have them ride in identical conditions for the same amount of time. One group wears helmets, one does not: which group has fewer head injuries? That’s the point – drivers giving less space to cyclists with helmets would have to cause more head injuries than the wearing of helmets prevents for your point to hold water. If, say, 100 injures are prevented but there are 10 more accidents, the net effect of helmet wearing is still beneficial.     

Head injuries to cyclists are in any case very rare (ordinary road cyclists, that is - off-road mountain biking is another matter), even in quite serious accidents. In accidents, riders generally fall over to one side, injring their arm and leg on that side, but not their head. Even when they go over the handlebars, they usually stick their arms out in front of them and don't hit their head.

So? House fires are also very rare, yet by law new builds have to be fitted with alarms. Should we change that law because houses don’t burn down that often either? Why not?   

Helmets project out from the head up to two inches, so the fact that a helmet is smashed doesn't necessarily mean that the cyclist's head would have been. There is some evidence that this fact means that helmets can cause serious neck injuries.

This reminds me of the (now long abandoned) argument against seatbelts – people in crashes could be trapped by them, therefore don’t wear a seatbelt. Can you see what’s wrong with that? There might be some additional injuries caused by helmets projections, but again you have to look at the hard numbers: are more injuries caused by helmet projections than are presented by wearing helmets at all, or vice versa? If it is  vice versa, then the net effect of helmet wearing is still beneficial.   

I think all of these facts are mentioned in the article, but BHS and BR avoid addressing them.

Not only did I address them, I rebutted them. You on the other hand have ignored those rebuttals.

BHS cxan talk about the fallacy of irrelevance, but it remains true that car users suffer considerably more head injuries than cyclists proportionally to their numbers, but no-one is nagging them into wearing helmets.

First, not according to the article they don’t, unless that is you think the difference between 0.41 injuries per million miles travelled and 0.46 injuries per million miles travelled is “considerable”. 

Second, you have still to find any relevance here. “We couldn’t persuade people in cars to wear helmets, therefore we shouldn’t persuade cyclists to wear helmets” is still a very bad argument whichever way you look at it. As I said before, if you couldn’t take out six bullies in the playground does that mean you should leave alone the one bully you could take out? Why not? 

[SteveH]

You're making baseless assumptions and plucking imaginary statistics out of the air. No doubt risk homeostasis also applies to seat belts (probably not much or at all to airbags, because they're hidden), but presumably there's a net increase in safety. There seems not to be with helmets. What helmets do do is give the impression that cycling is dangerous, and put people off cycling, which is bad for the environment and general health.

Then he turns to “how bike helmets may be harmful”. He continues: “In 2001, an article in the New York Times reported that the rate of bicycle head injuries had risen sharply — an increase of 51% — during a ten-year period when bicycle helmet use became widespread. This during a time when statistics showed an overall decrease in bicycling in the United States. No one knows for sure why head injuries among cyclists increased, but there are a few theories”. Note that “No one knows for sure why head injuries among cyclists increased”. Nor therefore do they know what the increase might have been had helmet-wearing not become more common. You’d need a comparable study to find that out, and absent that he seems to have fallen for a classic correlation = causation inference.

Correlation may not equal causation, but at the very least a 51% increase in head injuries at a time when cycle use was decreasing and helmet use becoming more common does strongly suggest that helmets offer no significant safty advantage. You can't just airily wave away statistics you don't like by saying that correlation doesn't equal causation. Otherise, I can also dismiss statistics suggesting that seast-belts offer significant safety advantages in the same way, whatever statistics you come up with.

[bluehillside Retd.]

Steve H,

You're making baseless assumptions and plucking imaginary statistics out of the air.

What baseless assumptions have I made and what imaginary statistics have I plucked?

No doubt risk homeostasis also applies to seat belts (probably not much or at all to airbags, because they're hidden), but presumably there's a net increase in safety.

Yep.

There seems not to be with helmets.

How do you know that? The article makes very clear from the beginning that helmets cause a dramatic improvement in the outcomes from head injuries. The NYT article it references says the same thing, and concludes: “Dr. Richard A. Schieber, a childhood injury prevention specialist at the Centers for Disease Control and Prevention and the leader of a national bicycle safety initiative, said public health officials were realizing that in addition to promoting helmet use, safety officials must teach good riding skills, promote good driving practices and create safer places for people to ride. ''We have moved the conversation from bicycle helmet use to bicycle safety,'' Dr. Schieber said. ''Thank God that the public health world is understanding there is more to bicycle safety than helmets.''

That’s an argument for helmet wearing, not against it. 
 

What helmets do do is give the impression that cycling is dangerous, and put people off cycling, which is bad for the environment and general health.

So you assert. Now who’s “making baseless assumptions and plucking imaginary statistics out of the air”?

[SteveH]

Steve H,

What baseless assumptions have I made and what imaginary statistics have I plucked?

If, say, 100 injures are prevented but there are 10 more accidents, the net effect of helmet wearing is still beneficial.

What helmets do do is give the impression that cycling is dangerous, and put people off cycling, which is bad for the environment and general health.

So you assert. Now who’s “making baseless assumptions and plucking imaginary statistics out of the air”?

Every country that has made helmet-wearing compulsory has seen a marked decrease in cycle use.

[bluehillside Retd.]

Steve H,

If, say, 100 injures are prevented but there are 10 more accidents, the net effect of helmet wearing is still beneficial.

You missed that "If, say..." at the beginning. I was illustrating a point, not quoting a statistic.

Every country that has made helmet-wearing compulsory has seen a marked decrease in cycle use.

Evidence?

Oh, and can you now see that the doctor quoted in the NYT was arguing for helmet us, not against it? 

[Udayana]

Suff stats ... social pressure causes people to change habits.

I always wear a helmet when cycling as I know that wife and offspring would be forever plagued by people asking "why wasn't he wearing a helmet?" when I'm dead.

[SteveH]

You missed that "If, say..." at the beginning. I was illustrating a point, not quoting a statistic.

The "If, say..." was the point: you were inventing statistics to bolster your case.

Evidence?

OK, I admit I was just saying what I'd read, and a quick google suggests that the evidence for reduced cycle use is inconclusive. However, I did come across this, which strongly suggests that helmets make no significant difference, since when use shot up dramatically from 43% to 92% in New Zealand following compulsion in the 90s, cyclist head injuries did not decline noticeably, more than they already were. https://www.cyclehelmets.org/papers/c2034.pdf "In New Zealand, most primaryschool children were already wearing
helmets (Fig 5),[8] but adult %HW increased from 43%-92%.[8 9] If helmet
laws were effective, %HI of adults
should have fallen substantially more
than primary-school children. In fact,
both had similar declining trends (Fig
5), implying that the substantial
increase in adult helmet wearing was of
very little benefit.
In Western Australia, helmet
wearing increased from negligible levels
before 1980 to about 37% just before
the law that increased it to 82%.[10] The
most dominant feature in %HI (Fig 6) is
a declining trend common to all road
users. Such trends appear to be
widespread, e.g. the almost identical
declining trends for cyclists and
pedestrians in the UK[11] and Victoria.[12]
Early analyses created considerable
confusion by ignoring such trends,[13 14] mistakenly assuming increased helmet wearing was the only possible
cause of declining %HI.
In WA, a large proportion of cyclists were injured in bike-only crashes, so there is no reason to believe
that, without the helmet law, %HI of cyclists would have followed the same trend as pedestrians (which
increased from 1990 to 1991 for no apparent reason.) When cyclists’ %HI is compared to that of all road
users, there is little or no evidence of any benefit from the helmet law. "

Oh, and can you now see that the doctor quoted in the NYT was arguing for helmet us, not against it?

Yes, but so what? The statistics are against him.

[ProfessorDavey]

As a (most) daily cyclist I always wear a helmet, but I do think the arguments over risk/safety are very complicated. I think the thing that worries me the most is the behaviour of motorists, being more risky in their behaviour towards helmet-wearing cyclists and non wearers.

So overall I am not in favour of making helmets compulsory, not least because I don't want to discourage anyone from cycling and making people have to wear a helmet will dissuade some. Perhaps the most important thing we can do to improve cyling safety is simply to cycle more and have more cyclists. Once huge numbers of cyclists become the norm rather than the exception driver behaviour will necessary change, and also strong pressure is put on road planners to invest in road safety measures.

And of course cycling is good for health and good for the environment (which in turn is good for health particularly in urban areas). So if you really want to assess the risk/benefit analysis of not wearing a helmet then you need to factor in the health benefit as well as the potential risk.

[bluehillside Retd.]

Steve H,

The "If, say..." was the point: you were inventing statistics to bolster your case.

Good grief. Try again: what I actually said was that IF the incidence of accidents increases when cyclists wear helmets (because they take more risks or because cars drive closer) THEN it would STILL make sense for everyone to wear helmets IF the NET TOTAL of brain injuries decreased despite the increased incidence of accidents. There was no inventing of statistics at all – it was just an illustration of a basic principle.

To set this out more clearly, IF say in a given number of miles cycled without helmets there are ten serious head injuries whereas with helmets that number reduces to two, then even IF the incidence of accidents went up by, say, 10% that would mean 11 serious head injuries without helmets and 2.2 with helmets. That is, in both cases the number of serious head injuries when everyone wears helmets reduces.

For your point to make sense you’d have to show that the increased incidence of accidents caused more net injuries than would have been the case if no-one wore helmets.           

OK, I admit I was just saying what I'd read, and a quick google suggests that the evidence for reduced cycle use is inconclusive. However, I did come across this, which strongly suggests that helmets make no significant difference, since when use shot up dramatically from 43% to 92% in New Zealand following compulsion in the 90s, cyclist head injuries did not decline noticeably, more than they already were. https://www.cyclehelmets.org/papers/c2034.pdf "In New Zealand, most primary school children were already wearing helmets (Fig 5),[8] but adult %HW increased from 43%-92%.[8 9] If helmet laws were effective, %HI of adults should have fallen substantially more than primary-school children. In fact, both had similar declining trends (Fig 5), implying that the substantial increase in adult helmet wearing was of very little benefit.

In Western Australia, helmet wearing increased from negligible levels before 1980 to about 37% just before the law that increased it to 82%.[10] The most dominant feature in %HI (Fig 6) is a declining trend common to all road users. Such trends appear to be widespread, e.g. the almost identical declining trends for cyclists and pedestrians in the UK[11] and Victoria.[12] Early analyses created considerable confusion by ignoring such trends,[13 14] mistakenly assuming increased helmet wearing was the only possible cause of declining %HI. In WA, a large proportion of cyclists were injured in bike-only crashes, so there is no reason to believe that, without the helmet law, %HI of cyclists would have followed the same trend as pedestrians (which increased from 1990 to 1991 for no apparent reason.) When cyclists’ %HI is compared to that of all road users, there is little or no evidence of any benefit from the helmet law."

Again, you seem to be arguing that “no significant difference” means we shouldn’t make any difference at all. It’s the fire alarms point again – a very small number of people die in house fires anyway, so why bother making fire alarms compulsory? The answer is that, even when total statistical differences are small, the significance to the individual (whether it's dying in a house fire or dying from a cracked skull) is huge.   

Yes, but so what? The statistics are against him.

No they’re not – the statistics support him. What he’s saying is that they could be even better though if, in addition to promoting helmet wearing, public health officials promoted additional risk aversion strategies. 

[ProfessorDavey]

To set this out more clearly, IF say in a given number of miles cycled without helmets there are ten serious head injuries whereas with helmets that number reduces to two, then even IF the incidence of accidents went up by, say, 10% that would mean 11 serious head injuries without helmets and 2.2 with helmets. That is, in both cases the number of serious head injuries when everyone wears helmets reduces.

I think that is too simplistic, as you are only assessing serious head injuries. There are, of course, all sorts of other injuries, serious or otherwise, that arise from bike accidents.

So lets say your total number of accidents went up from 10,000 to 11,000 due to more risky behaviour by cyclists and motorists on the basis of making helmet wearing compulsory. Even if the number of serious head injuries goes down from 11 to 2.2 (if that's possible) you'd still need to factor in the effect of the additional 1000 total accidents - so how many more serious fractures, how many cases of major internal organ injury, how many deaths for that matter (noting that not all would be caused by head injuries).

It is complicated.

[bluehillside Retd.]

Hi Prof,

I think that is too simplistic, as you are only assessing serious head injuries. There are, of course, all sorts of other injuries, serious or otherwise, that arise from bike accidents.

So lets say your total number of accidents went up from 10,000 to 11,000 due to more risky behaviour by cyclists and motorists on the basis of making helmet wearing compulsory. Even if the number of serious head injuries goes down from 11 to 2.2 (if that's possible) you'd still need to factor in the effect of the additional 1000 total accidents - so how many more serious fractures, how many cases of major internal organ injury, how many deaths for that matter (noting that not all would be caused by head injuries).

It is complicated.

Yes I know it is, but I was responding to Steve H’s basic implication that wearing helmets causes more rather than fewer serious head injuries (because cyclists take more risks and cars overtake with less room).

Re less serious accidents, yes but you’d need to offset the extra minor injuries with helmets against the reduction in minor injuries from not wearing helmets too. You can’t just add in the minor injuries from more reckless behaviour without considering the flip side – helmets reduce minor injuries too. The basic point is that you cannot just say “more accidents, therefore helmets bad”. You need to look at the overall, net effect. 

[ProfessorDavey]

Re less serious accidents, yes but you’d need to offset the extra minor injuries with helmets against the reduction in minor injuries from not wearing helmets too. You can’t just add in the minor injuries from more reckless behaviour without considering the flip side – helmets reduce minor injuries too. The basic point is that you cannot just say “more accidents, therefore helmets bad”. You need to look at the overall, net effect.

Not all accidents that don't involve head injuries are 'less serious' than those that do. If there are more accidents it is likely that there will be more serious accidents too. For example why would a spinal injury that results in someone being wheelchair bound somehow be 'minor'.

And don't forget that many (perhaps most) cycling deaths are the result of crushing injuries caused by collision with large vehicles at low speed. In many cases the vehicle passing too close to the cyclist or turning across them is a major contributory factor. Wearing a helmet wont help at all in these cases, but risky behaviour on the part of the driver will certainly increase risk.

[jeremyp]

I think that is too simplistic, as you are only assessing serious head injuries. There are, of course, all sorts of other injuries, serious or otherwise, that arise from bike accidents.

One of the problems of the article is that the nature of the accidents and the nature of the head injuries is not stated. For example:

In 2001, an article in the New York Times reported that the rate of bicycle head injuries had risen sharply — an increase of 51% — during a ten-year period when bicycle helmet use became widespread

What does that mean? Who are they counting? Here is a story that illustrates a small part of the difficulties to which PD is alluding.

At the beginning of the First World War the soldiers of the British Army were equipped with a soft peaked cap to wear on their heads. As the war progressed, it became obvious that there was serious danger from objects falling from the sky. When artillery shells landed (and there were a lot of artillery shells), they would exploded, killing anybody nearby but they would also throw lots of dirt and stones and bits of dead soldier into the air which would eventually come down often on top of other soldiers.

In late 1915 and early 1916 they introduced steel helmets for all soldiers and the cases of head injuries soon started to .......

... increase. Staff at medical posts were seeing more head injuries than before. Why? Well the reason was, of course that the events that caused the injuries they were seeing would not have been survivable and the medical staff would not have seen them at all.

So, if the data for the 51% quoted above was gathered by looking at A&E records, you need to be sure that the extra injuries are not coming from people who would previously have been killed.

You have to be really careful with the data to be sure exactly what you are counting.

Note: Steve, I am not necessarily disagreeing with you. If the statistic of 0.41 head injuries (Is that all head injuries? severe head injuries? How did they estimate the million hours, especially for pedestrians)  per million hours is the case, the risk is fairly low - it's a rate of less one head injury in two hundred years for an individual cyclist.