Bike helmets and safety: a case study in difficult epidemiology

Well written article, but I didn’t see anything more conclusive than “this shit is hard to pin down.” Obligatory “I crashed and my helmet saved my life” anecdote from me here; it did.

That aside, the article spends most of its time examining the repercussions of mandated helmets that might cause people to shirk the law, which is definitely a salient aspect. However, there’s minimal mention of the type of injuries or damage that helmets mitigate. Really, the helmet is only designed to protect your skull and brain from sudden physical impact. The helmet won’t save you from cervical injuries caused by direct or glancing blows. It can’t. Is that reason not to wear a helmet? Not at all. You can break your skull from a standing position, on two feet. It’s simple physics. I find the article rather lacking this examination.

I laugh at people who claim that the helmet restricts them in any way. If you’re not wearing one of those dumb Bern helmets which isn’t design for cycling at all, there’s no physical way for the helmet to obstruct anything, sound or movement. All serious riders will lecture you for not wearing a helmet, not because they necessarily read a study or know a friend who survived a crash, but because common sense tells you if you happen to hit your head in a crash, you’re better off wearing a helmet.


In addition to reducing the chances of an actual skull fracture from the head hitting metal or pavement.


That’s how.

Christ, people get worked up over how seatbelts and helmets are “Orwellian”, but the NSA collecting information on all electronic communication? Meh.


I am a “serious cyclist”. I commute about 23km each way every day, summer and winter. I ride with a cycling club on weekends and take cycling vacations to places like the Pyrenees. I crash my roadbike about once every 10 years on average (4 times in 40 years of cycling). On all but one occasion, the crashes were my fault (or at least no-one else’s). My helmet certainly saved me from a serious head injury (or worse) in one instance. My head hit the road HARD. Without the helmet, it would have been much worse. My wife has been saved from a serious head injury by her helmet. Whenever it comes up, nearly everyone in my bike club has an anecdote in which their helmet saved them from a serious head injury. I am vehemently pro-helmet, yet against compulsory helmet laws. Not a “freedom” or “rights” thing but I simply acknowledge that many are discouraged from cycling by helmet laws. That is to everyone’s detriment.


Nine years ago I was hit by another cyclist while racing downhill and around the corner. I skidded across the street on my shoulder and head, splitting my helmet and bloodying my knees. I am very glad not to know what the impact and drag would have done to my scalp, scull and neck.

While I do occasionally enjoy riding without a helmet, I do have a danger threshold after which I am never without one. Precarious situations? Wear a helmet. Official event? Wear a helmet. But helmets cannot prevent all damage and cyclists (and motorists) should have a certain freedom to assess their risks.


What is missed in the arguments here is that the article is talking population effects, not individual. Helmets save more damage than they cause during accidents; but is the population effect such that we lose overall health benefit from reduced harm during an accident because people cycle less, cycle more carelessly or drivers drive more carelessly? People are very used to helmets now in countries that it is mandatory, so I think we will see the equation end up in favour of an overall benefit from helmet laws. In addition helmets are so much more comfortable than in the early late 80s when they first commonly appeared. .


Nonsense. Anyone saying that is merely parroting propaganda.

Analysis of government data shows 41.7% fewer Australians cycling daily in 2013 than in 1985/86, despite population growth of 43.2%.

This is just another example of everybody being fucked over to serve the interests of a few. A dumb-arse law like this is an easy sell to politicians, with its common-sense appeal and only counter-intuitive (to simpletons) ‘unintended’ consequences… I say ‘unintended’ because I’m reminded of other, more egregiously obvious, grave injuries to public amenity in favour of pushing everybody into cars… why were bodies like the RACV (a statewide motorist’s insurance organisation) so interested in pushing helmet law?

People who drive cars more spend more money doing so than people who ride bikes more. Who gives a fuck if they die 10 years earlier and living in a traffic jam sucks arse; the important thing is that we wrung a few more bucks from them before they died. All this sacrifice is upon the altar of GDP; gotta keep the wheels of the economy turning, not to mention scratch the backs of your old school pals on the other side of the government / big business revolving door.

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A thousand times, yes.

And that goes for @starrygordon below, too.

There are many bad things about helmets, but the worst is their political effect: they give people the idea that there is something weird and dangerous about riding a bicycle in the streets. Their evident effect, for many people, is that the cyclist is seen as a mental child playing games in front of serious adults trying to go about their business, which of course they must do in a car because they are serious adults. Other fairly serious drawbacks of helmets are: they’re ugly, uncomfortable, ineffective, excuses to harass people, excuses for bad driving, excuses for police harassment, often are too lightly made to be effective, discourage people from riding, and submitting to their imposition will reward helmet nannies and helmet fascists, which may cause them to exhibit their unpleasant social behaviors in other areas of life.

More generally, helmets and helmet advocacy contribute to the growing public fashion for panic, fear and insecurity, thus providing a cultural basis for increased surveillance, repression, and the police state in general.


[quote=“JonS, post:21, topic:16635, full:true”]
2045singularity said:
the helmet could possibly restrict my ability to move my arms quickly around my head area when I agilely roll to break my fall, thus wearing a helmet could cause a serious head injury for me if I crash because the helmet would likely restrict my movement, my agility, I would be less free to move in an unrestrained manner, thus my ability to self-protect my head could be diminished due to the physical restrictions of the helmet.
So much hubris.
[/quote]Not to mention impeding my ability to defeat a dozen ninjas.


A friend died in high school from a cranial hematoma caused by falling off his bike and hitting his head on a rock. If he’d had a helmet on, he would most certainly have lived.

Plus I’m an epidemiologist and I love all things stats and math and complicated and stuff. But for many things, what do we need epidemiology for, when we have medicine?


I’m over 30, Vancouver Canada. Here helmets have been compulsory for so long that we all think those not wearing them are idiots - I’ve worn one as long as I can remember and feel strange without one. My helmet has yet to save my cranium from a crash.

Very interesting to see this debate. It’s especially poignant as Vancouver is both expanding bicycle lanes and attempting to set up a bike-rental program. Helmets have been a serious challenge for the rental program, and they have invented vending machines to provide them.

I could see how helmets would be very restrictive to a low-speed cross-town jaunt - assuming roads are relatively safe. This takes correct city design and appropriate motorist culture. MHLs may select for the kind of rider I am: I hit 30-40mph (50+ kph) each trip - I’d be an idiot not to wear a helmet.


To point out simple facts like the risk of sustaining a serious head injury on a bike is half what it is in a car.

In any discussion like this, there’s always someone who pipes up saying they had a terrible accident in which a helmet saved their life and that’s why everyone should be forced to use one, but even assuming they’re correct in the obvious assumption that they wouldn’t have survived without a helmet, that doesn’t amount to hill of beans - the plural of anecdote isn’t data, as you should well know.

People don’t think it’s reasonable to wear a helmet in a car just in case of head injury, but that risk is double the risk cyclists are being persecuted over, and a trifling fraction of the health risk they’re avoiding by being on a bike.

So to anyone who wants to make me wear a helmet on my bike, you can mind your own fucking business, thanks.

Ok, but I refuse to pay for your healthcare since you are assuming so much extra risk. Spend a week in a hospital for treatment of a head injury that was easily preventable with a cheap bicycle helmet? That should all come out of your pocket, not society’s – or mine.

Same argument applies to smoking, really. Do it all you want, just don’t make me pay for the effects of your risky behavior.


Um, blow it out your ear?

Unless you care to live a life audited for risk from go to whoah.

Stingy bastard. That’s an American disease; quit spreading it.

Don’t get me started on this, I’m fucking militant on the subject…

I have at least the minimum amount of respect for other adults. This includes the capacity to mind my own fucking business; it’s your life you’re responsible for, and a few cents out of my tax if you fuck it up is nothing next to the price of fucking up, so I should just STFU rather than stick my nose in your business telling you how to cross the road or what drugs you’re allowed to take and so forth.

Not that I’m an absolutist; at some point collective responsibility outweighs individual freedom.

But the line is between helmets and seatbelts - look at the goddamn evidence.

…Which says, for one thing, that you should keep your bloody trap shut when it comes to criticising cyclists, if you don’t want to spend money on avoidable healthcare. You should be doing everything you can to encourage cycling, whether people wear helmets or not. And I bet that also goes for whether they submit to half-arsed road rules or not too.


Drivers don’t want me to have it all. They want to give me a scare without the risk of them being locked up, so if I don’t wear a helmet, they will take more care because I look vulnerable. But knowing this, I can find other ways to look vulnerable and get the best of both worlds.


There’s one obvious difference between cycling without a helmet and smoking: the effects of smoking are very clear on a population level, but no population studies have ever shown any benefit from cycle helmets.

I treat the matter like any other medical intervention: an assessment of the risk shows that it’s very small (it’s more unhealthy not to cycle than to cycle, even with the attendant risks, and I hope you’re already extending your policy of not paying for avoidable risk to people who don’t take regular exercise), and as far as we can tell from the population studies, any benefit friom wearing a helmet is very small, if it exists at all. (It’s very possible that helmets do save lives, although that’s not what the manufacturers claim, or what they are designed for; but either this effect is so small as to be lost in the noise, or there’s some contradictory effect which increases risk.)

How else are we supposed to work out whether an intervention in general does more good than harm, other than by epidemiology? We’re all familiar with people who claim that some treatment worked wonders for them: some are well founded, some are rubbish. If a study the size of a national population doesn’t show a benefit, we should be doubtful; if every such study so far shows no benefit, we can cautiously infer that the effect either just doesn’t exist, or is counterbalanced by some other factor. That’s where cycle helmets are at the moment, as far as I know.

It shouldn’t come as a shock to BB readers that some things are counterintuitive, or that common sense can be wrong. Cycle helmets just seem to be one of those things.


I suggest a bike helmet that looks like a giant head, maybe with fake hair.

Ah, @marktech, you want to play my favorite game on the Internet, My Data Can Beat Up Your Data? Very well then.

There are several meta-analyses and reviews which synthesize and evaluate the results of multiple case-control studies. A Cochrane review of case-control studies of bicycle helmets by Thompson et al. found that “helmets provide a 63 to 88% reduction in the risk of head, brain and severe brain injury for all ages of bicyclists. Helmets provide equal levels of protection for crashes involving motor vehicles (69%) and crashes from all other causes (68%). Injuries to the upper and mid facial areas are reduced 65%.”

A 2001 meta-analysis of sixteen studies by Attewell et al. found that, compared to helmeted cyclists, unhelmeted cyclists were 2.4 times more likely to sustain a brain injury; 2.5 times more likely to sustain a head injury; and 3.7 times more likely to sustain a fatal injury.

I guess it’s like smoking data in the 1930s and 1940s – “the jury is still out!”

I think it is fine if people want to cycle without helmets, the risk is certainly lower than, say, motorcycling without a helmet which is borderline suicidal given the vast difference in physics energy and regular exposure to motor vehicles. But when you learn that 62% of bicycle related deaths are head injuries…

Each year, nearly 1,000 persons die from injuries caused by bicycle crashes, and 550,000 persons are treated in emergency departments for injuries related to bicycle riding. Approximately 6% of the bicycle riders treated in emergency departments require hospitalization. Head injuries account for 62% of bicycle-related deaths, for 33% of bicycle-related emergency department visits, and for 67% of bicycle-related hospital admissions.

… It seems awfully dumb not to slap a $20 bicycle helmet on your head to mitigate that risk.


It seems commonsense to say that helmets save lives by protecting the skull in the case of accident. However, commonsense isn’t very scientific, and a lot of things I have thought were obvious have turned out not to be the case.

It should be relatively easy to test the relative benefits of helmet wearing. Most cyclists I see in the UK seem to wear them, most cyclists I see in the Netherlands do not. Compare and contrast the relative risks and benefits to the two populations in a scientific manner maybe?

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Again, you’re comparing cycle helmets - which show no measurable effect in population studies - with smoking, one of the most well-attested dangers to health.

The reviews you cite are based almost entirely on necessarily small-scale case-control studies (the authors of the Cochrane Report helpfully included four of their own papers in the seven studies they considered), and are contradicted by all the population data we have. Why place more weight on the smaller studies than on huge datasets collected on national levels? And why, if there is any generally useful benefit to wearing a helmet, does it never show up in population studies?

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