Wednesday, June 14, 2006

Bicycle helmets and risk-reward calculations

Since Kevin raised the issue, I thought I would present some of the arguments against the campaign for compulsory helmet use for cyclists. Unfortunately, few people come to the debate with a sufficiently open mind as to allow the facts to influence their beliefs, but here goes anyway:
  1. Cycling is already safe and not in any way deserving of special safety equipment
  2. The health benefits of cycling massively outweigh the risks
  3. Helmets are pretty useless anyway, and can be expected to make some types of brain injury worse
  4. Risk compensation means that those who believe helmets to be useful will not be safer
  5. There are many higher priorities for safe(r) roads
  6. Heat stress is a real issue (sometimes)
  7. There is no evidence from population studies that helmet legislation (or increased wearing) makes cycling safer
  8. Cycling is safer where more people cycle and fewer helmets are worn
  9. Pro-helmet 'science' is junk pushed by ignorant shroud-waving nannying do-gooders and the helmet industry
I don't claim that is exhaustive, but it should do for now :-)

There are many detailed explanations of the above points to be found on the internet, eg here and here. It's not necessary to accept all the above points in order to conclude that helmet legislation (and perhaps even promotion of their wearing) is at best a distraction from the real issues, and more likely actually damaging in terms of public health alone, let alone the sort of values that we claim to hold dear (eg freedom from unnecessary interference by pettifogging bureaucrats and shroud-waving nannying do-gooders).

I used to routinely wear a helmet when cycling, but gradually came to realise, as I investigated the subject, that there wasn't really any justification for it. In Japan, the summer is hot enough that it was really unpleasant and definitely distracting. The final straw was on discovering a trivial error in a published study, the correction of which demonstrated that their data actually showed helmets to have (at best) a minor influence on safety rather than being the dominant factor they had claimed them to be. The authors' response was basically to say that they still believed their main conclusions even though the data didn't support it! If that is the best they can come up with, I'm distinctly unimpressed. Most of the other oft-cited studies have well-known flaws - in the most infamous example of which, the authors produced a revised analysis (showing a lower benefit from helmet wearing than their original work) but the incorrect (but more impressive) figures are still routinely cited by "safety campaigners".

There are, of course, several differences between powered two-wheelers and bicycles, which may tip the balance more in favour of helmets for the former (I don't claim to know much about the m/c case). But I'm disappointed that Kevin's promised "risk analysis" consists of nothing more than "it's common sense innit". The evidence clearly indicates otherwise, for me anyway. And how many of the "it's common sense innit" crowd wear walking helmets, or even buy them for their children?

If any of you non-cyclists still disagree with me...too bad, I'm cleverer than you and here's the proof :-) As for any cyclists who are still attached to their magic hats, well every rule has its exceptions. It's worth bearing in mind that the UK Govt has stated that one reason it does not support helmet compulsion for cyclists is that the wearing rate is currently too low for it to be workable - so every time you exercise your right to choose to wear a helmet, you are helping to bring forward the day when that right to choose will be removed.

Rant over. I'm off for a bike ride...


Anonymous said...

I'm going to respond to you list as if they were reasons why you or I don't need to wear them. I think mandatory laws are idiotic, but you seem to take the arguments against the laws as a reason why you don't need to wear your helmet. Two different issues.

1) Well yes it is, but if you put in a lot of miles you are going to crash. Some much more then others. If you don't put in many miles then the risks are small.
2) True but so what?
3) I think really doubt this is true.
I've seen a lot of compressed and broken helmets where the rider has walked away from the accident. I don't believe that in the vast majority of accidents when the foam is severely
compressed that the helmet did not help significantly. In over 100,000 miles of cycling I've hit my head twice. Once as a child and a helmet may have helped. Once as an adult where I landed on my forehead which compressed the foam to half its prior width--it defiantly helped.

The types of accidents where the helmet makes matters worse, is
where it binds on something and causes the neck to rotate. I've never seen this, so I doubt it is very common.

After many years of riding, my father went out with out his helmet once. He crashed 2 miles from home and spent 2 weeks in the hospital because of the head injury.
Try this experiment. Drop half a brick from 6" above your head with a helmet on. Now try it without. After your done, let me know if you think a helmet is a good idea.

4) True for some people. Probably true for me, but i would likely go so much slower that I would not enjoy cycling nearly as much. I do very fast long downhills, hitting 45 mph on the final decent of almost every ride I do. I'm not willing to give that up.
5) Yeah so? Until the roads are safer, wear your helmet.
6) This is usually an excuse. There is a difference between being comfortable because it is hot, and having a real problem with heat. If you are really having a problem with heat, stop and cool off. If the heat is keeping you off your bicycle then this is may be valid. I rode for 7 years in Texas, don't think Japan is worse.
7) Well I agree that there shouldn't be laws. But again how good are the studies?
8) what Kevin said
9) And anti-helmet science is published by grumpy libertarian
curmudgeons. The science is poor.


jules said...

P.S. James does wear a bicycle helmet while mountain biking, because he is always hitting his head on trees and low hanging braches. However, it is rather different from road cycling, where you are much less likely to fly straight into an obstacle. Perhaps the brick-dropping analogy is more suitable for mountain biking. In road biking you more often just loose an awful lot of skin sliding along the road. (ow ow ow ow ow!)

P.P.S. I think he neeeeeds a Thudguard! James often bangs his heads on low hanging beams and other articles (waaay up in the skyyy as far as most Japanese are concerend), the injuries from which are made all the worse by his thinning hair! A hat doesn't help since the brim obscures sight of offending articles. Poor lamb.

James Annan said...

As I said, it's rare to find anyone who comes to this debate with an open mind...

There is plenty of this "debate" all over usenet, and not much point regurgitating it here. Interested people will have a look for themselves, including the urls I already provided.

However, in the spirit of Kevin's original claims of "risk analysis", I am definitely interested in hearing from anyone who can give any rational risk analysis which supports wearing a helmet on a bicycle, but not in a car or as a pedestrian. What are the criteria by which such behaviour can be rationally justified, and in what areas of your life do you apply them? Eg, does your risk analysis also discourage you from swimming, for example?

Brian said...

I'd have to disagree with Kevin regarding reason #2 - it "seems" likely that even a minor reduction in enjoying a helmet-besotted ride would somewhat reduce the number and length of rides. It's just a question of how the numbers work out.

FWIW, I do wear a helmet except when I'm riding tame bicycle paths to work. I also have little doubt that helmets are very necessary when riding motorcycles.

Anonymous said...

I actually do have an open mind. I have read the arguments about helmets in other places. The arguemnts haven't seemed to change in 10 years. Don't wear your helmet you'll probably be fine. If its a risk your willing to take fine. I'm not.

I just can't ignore my experience from 40 years of road riding. I've
seen too many broken helmets and head injuries. I haven't
seen many head injuries among pedestrians, and I see a lot more pedestrians. The few pedestrians head injuries I've seen were from cars. It would have made more sense for them to be careful when crossing the street rather then putting on a helmet.

It may make sense, to wear a helmet when driving, but who said I was rational? As for swimming, there are many cases where I've modified my behavor because of the risks: mainly by not swimming when I thought it was dangerous.

I agree that accidents for road cyclist are mostly road rash and broken collar bones. The risks are much greater for those that ride in packs. You can convince me the risks are not very big (subject to an appropriate definition of "not very big") , but I still think it makes sense to wear a helmet. I've never had a car accident but I still wear a seat belt. From a saftey stand point I have more of a reason to wear a helmet then a seat belt and the incovience of each is similar.


Anonymous said...

i dunno Brian. I can work up all sorts of excuses to not go on a ride, such as "If I try to schlep my ass up that 3-mile/8% grade my heart is going to explode all over the road." But I can put, "I hate wearing a helmet!" in the list of (real) reasons people won't ride. Maybe....

James, I'm working up something for you now that I'll post on my blog. It's a list of data required in order to make a true risk comparison across the spectrum of activities. But I don't think this is (well, for me anyway) about not having an open mind. I love seeing conventional wisdom thrown on its head by data (a.k.a. Freakanomics). But the quick risk-analysis calculation I made in my head without the data in front of me said that motorcycling without a helmet at 60mph (ok, fine, 100 km/hr) is dumb while crossing the street without one isn't. I wasn't trying to be preachy/closed minded in my original post, any more than saying, "Um, dude, sniffing glue isn't good for you" is being preachy/closed minded.

James Annan said...

Ok, I'll add just a few words about the discouragement aspect.

First, the fact that Kevin (or anyone else in paticular) is happy to wear a helmet is fundamentally irrelevant to whether helmet promotion/legislation acts as a deterrent to cycling. By definition, the promotion/legislation only affects people who are not already wearing helmets! I think it would be reasonable to accept that such people have considered the matter as carefully as Kevin (possibly more so!), reached a different conclusion, and will find the imposition to act as some sort of deterrent, whether minor or major. It hardly needs to be a major effect for the costs to outweigh the benefits in terms of public health. And of course, the effects have been noted in countries where legislation has been brought in.

Secondly, when a parent packs their child off to school, they can generally either (a) drive them (b) let them walk (c) use public transport or (d) ride a bike BUT IF YOU LET THEM RIDE A BIKE YOU HAVE TO MAKE THEM WEAR A HELMET OR ELSE YOU ARE A BAD PARENT WHO DOESN'T CARE ABOUT THEIR CHILD BECAUSE EVERYONE KNOWS IT'S TOOOOO DANGEROUSSSSSS TO RIDE A BICYCLE WITHOUT A HELMET.

In that sort of atmosphere, does anyone genuinely think it is surprising when parents (and schools) dissuade or even forbid children from cycling, helmet or not?

It is no secret that traffic danger is routinely cited in surveys as a major reason why people don't cycle more. Now, I have my doubts about the precise honesty of that (I reckon it's often just a more socially acceptable excuse than the more honest "cos I'm too lazy/don't want to") but it would be difficult to pretend it doesn't play a part. The UK Govt recently promoted helmet use with pictures of an x-rayed skeleton wearing a helmet - what sort of impression do you think that will make on parents? Pro-helmet campaigners openly and deliberately play up these fears, to the point that even normally rational people start to believe that there must be something in it...

Anonymous said...

I know nothing about the issues so it doesn't mean much if I say I buy your arguments for saying helmet compulsion is a bad idea.

It seems common sense to me that it is a good idea to be wearing a helmet if/when you have an accident. This doesn't mean it should be compulsory. The potential for the side effects of the compulsion to be worse than the benefit derived is important and needs to be considered.

The problem I see with your post is that it seems you are trying to use arguments against compulsion to say people shouldn't wear helmets. I would have thought a more important message would be that people should have the freedom to wear a helpmet if they want.

Do you take the same view on considering whether the side effects of Kyoto and similar agreements need to be shown to be less bad than the disease? Has that been done and how well?


Anonymous said...

Believe it or not I agree with James about the discouragemnet. I think he is completely correct. This is the main reason why think the laws are a bad idea.


James Annan said...


I'm mildly anti-helmet because the image they portray (of cycling being a uniquely dangerous activity that you have to be mad or reckless to consider) is wholly disproportionate and IMO does more harm than the helmet itself can do good. Outside of the USA and parts of Europe (primarily the UK), cycling is just something that many ordinary people do as part of their normal lives. But ultimately I've no real problem with people wearing what they want.

Kyoto: well, most of the debate is on whether the costs exceed the benefits. IMO there are also moral and ethical arguments that can weigh against the costs/benefits (potentially on either side). I certainly don't think that anything needs to be proven beyond doubt before "action" is taken, as even inaction is an action. Rather, it is a matter of making reasonable expectations and estimations. While people argue the angels-on-a-pin stuff about whether global warming has been "proven" to a specific level, they are largely missing this point.

scole999 said...

I understand the argument on both sides. It is very much like the motorcycle helmet debate. I think it should be voluntary for adults and mandatory for children. That would seem to be the conservative stance on the issue.

The Reflective Tape

James Annan said...

I don't understand how you can claim mandatory helmets for anyone is "conservative".

5330 said...

It's ironic that the Google ads at the top of the post are advertising cycling gear, including helmets.