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Science writer Ben Goldacre & statistician David Spiegelhalter cast critical eye over helmet studies. Conclusion? It's complicated.....

Science writer Ben Goldacre and statistician David Spiegelhalter say that issues surrounding arguments for and against cycle helmets are so complex that they appear to be in conflict with the British Medical Association’s official policy, “which confidently calls for compulsory helmet legislation.”

The pair joined forces to address what is perhaps the most contentious of cycling topics – a subject they freely admit they “both dread questions about” – and, specifically, the issue of whether studies can conclusively settle the debate either way.

Their main conclusions after outlining some of the problems associated with trying to establish the benefit or otherwise of helmets through scientific means?

“The current uncertainty about any benefit from helmet wearing or promotion is unlikely to be substantially reduced by further research,” and, “we can be certain that helmets will continue to be debated, and at length.”

Goldacre, who besides being the author of Bad Science and Bad Pharma, is Wellcome research fellow in epidemiology at the London School of Hygiene and Tropical Medicine, and Spiegelhalter, Winton Professor of the Public Understanding of Risk at the University of Cambridge, were writing in the British Medical Journal (BMJ).

At the outset, they say: “We have both spent a large part of our working lives discussing statistics and risk with the general public. We both dread questions about bicycle helmets. The arguments are often heated and personal; but they also illustrate some of the most fascinating challenges for epidemiology, risk communication, and evidence based policy.”

They identify two broad areas that science seeks to address when it comes to cycle helmets: “At a societal level, ‘what is the effect of a public health policy that requires or promotes helmets?’ and at an individual level, ’what is the effect of wearing a helmet?’ Both questions are methodologically challenging and contentious,” they add.

Goldacre and Spiegelhalter single out one recent study, led by Jessica Dennis at the University of Toronto, which held that compulsory helmet laws in various Canadian provinces had achieved only a “minimal” effect on hospital admissions for head injuries related to cycling.

The pair acknowledge that other studies have reached different conclusions, but describe the one conducted by Dennis as having “somewhat superior methodology—controlling for background trends and modelling head injuries as a proportion of all cycling injuries.”

By contrast, they say, case-control studies, which often find reduced rates of head injury among cyclists wearing helmets compared to those who do not, “are vulnerable to many methodological shortcomings” – for example, “if the controls are cyclists presenting with other injuries in the emergency department, then analyses are conditional on having an accident and therefore assume that wearing a helmet does not change the overall accident risk.”

Other variables they identify and describe as “generally unmeasured and perhaps even unmeasurable” include the fact that people who choose to wear helmets may be more risk-averse than those who do not, plus whether there is an element of “risk compensation” in play among those forced to wear helmets in places where they are required by law.

They run through some of the issues that opponents of helmet compulsion make, including that making them mandatory negates the positive health benefits, but again outline that the issue is more complicated than it appears on the face of it, citing a study that identified “two broad subpopulations of cyclist,” each of which would react differently to the introduction of compulsory helmet laws.

That study, carried out by the Institute of Transport Economics in the Norwegian capital, Oslo, described the country’s cyclists as comprising “one speed-happy group that cycle fast and have lots of cycle equipment including helmets, and one traditional kind of cyclist without much equipment, cycling slowly.”

The Norwegian study added: “With all the limitations that have to be placed on a cross sectional study such as this, the results indicate that at least part of the reason why helmet laws do not appear to be beneficial is that they disproportionately discourage the safest cyclists.”

The BMJ article says that “statistical models for the overall impact of helmet habits are therefore inevitably complex and based on speculative assumptions,” and that “this complexity seems at odds with the current official BMA policy, which confidently calls for compulsory helmet legislation.”

“Standing over all this methodological complexity is a layer of politics, culture, and psychology,” they say – whether that be anecdotal evidence of acquaintances who avoided injury through wearing a helmet, or “risks and benefits may be exaggerated or discounted depending on the emotional response to the idea of a helmet.”

They also point out that the Netherlands and Denmark, for example, have high rates of cycling but low rates of helmet wearing and cyclist casualties, which they suggest results from deployment of decent infrastructure, legislation aimed at protecting riders, and cycling itself being viewed as “a popular, routine, non-sporty, non-risky behaviour.”

Goldacre and Spiegelhalter do however see something of value in the helmet debate, but it’s not related to the actual wearing or non-wearing of one, or whether they should be made mandatory.

“The enduring popularity of helmets as a proposed major intervention for increased road safety may therefore lie not with their direct benefits – which seem too modest to capture compared with other strategies – but more with the cultural, psychological, and political aspects of popular debate around risk,” they say.

Born in Scotland, Simon moved to London aged seven and now lives in the Oxfordshire Cotswolds with his miniature schnauzer, Elodie. He fell in love with cycling one Saturday morning in 1994 while living in Italy when Milan-San Remo went past his front door. A daily cycle commuter in London back before riding to work started to boom, he's been news editor at road.cc since 2009. Handily for work, he speaks French and Italian. He doesn't get to ride his Colnago as often as he'd like, and freely admits he's much more adept at cooking than fettling with bikes.

71 comments

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Some Fella [890 posts] 2 years ago
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Im glad that is settled then.........................
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Pitstone Peddler [104 posts] 2 years ago
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its all down to strap tightness. Dont get them started on the impact of aeroshells on helmets and the resultant speed increases caused by having all those watts to be spare  3 26

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Tom Amos [236 posts] 2 years ago
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If I'm doing a stage of the tour de france and reaching speeds of 80kmh, I'll wear my helmet. If I'm cycling to the shops to buy a pint of milk, I won't. End of debate.

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Pitstone Peddler [104 posts] 2 years ago
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clunk click every trip

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burtthebike [169 posts] 2 years ago
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The real problem is why the BMA changed its policy on spurious grounds and haven't revisited that decision, despite promising to do so. As one commentator so accurately pointed out, the BMA is a trade union for ex-medical students, not a medical body. Its decisions are certainly not based on evidence.

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kie7077 [833 posts] 2 years ago
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Bicycle helmets are only rated for 12mph, question is, how effective are they at 20mph, 30mph, 40mph etc?

Does the polystyrene compress at those speeds or does the force just get transferred straight to the skull and brain, because if the force gets transferred then helmets become less effective at over 12mph.

There are also snagging and hanging risks to take into consideration. And helmets can make rotational head injuries worse.

I have not ever read anything that sounds scientifically and methodically correct that convinces me that helmets will increase my safety whilst I'm cycling along at 15-25mph. If a helmet works at these speeds then why doesn't someone prove it, that's what crash test dummys, accelerometers and control tests are for.  26

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Tripod16 [149 posts] 2 years ago
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I believe the pro-peloton are the crash test dummies...  26

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Ghedebrav [1098 posts] 2 years ago
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Yup, practically impossible to prove either way. I always wear mine, for the much more practical reason that my wife wouldn't let me on a bike without one.

Just a thought as well, I've only had one vaguely nasty crash, with a couple of broken ribs; my head made very hard contact with the tarmac, but a helmet was in the way, probably preventing at least an unpleasant and stitch-worthy gash. However, that experience (familiar to many of you, I don't doubt) would not have been recorded in any set of relevant data. My hunch is that on balance if you're out on the road riding at pace it's worth wearing one. For Dutch-style commuting/pottering, perhaps not.

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Colin Peyresourde [1636 posts] 2 years ago
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Tripod16 wrote:

I believe the pro-peloton are the crash test dummies...  26

Yeah, ask Ryder Hyjesdahl.

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Ham-planet [112 posts] 2 years ago
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kie7077 wrote:

Bicycle helmets are only rated for 12mph, question is, how effective are they at 20mph, 30mph, 40mph etc?

Your forward speed has little to no bearing on the effectiveness of a bicycle helmet, providing it has an appropriately low friction exterior.

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Forester [111 posts] 2 years ago
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I have a cracked helmet in my shed which saved my head when I sustained 12 fractures in a 20 kph crash after my front wheel went into a gully by the country lane I was cycling down. I feel it is the individual's choice but my wife was happy to look after me and would have been upset if I was a vegetable as well as chairbound. Now starting to ride again with nice new Lazer helmet.

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racingcondor [153 posts] 2 years ago
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Ham-planet wrote:
kie7077 wrote:

Bicycle helmets are only rated for 12mph, question is, how effective are they at 20mph, 30mph, 40mph etc?

Your forward speed has little to no bearing on the effectiveness of a bicycle helmet, providing it has an appropriately low friction exterior.

Yup. They're only rated for reasonably low impacts because the speed that they have to cancel is equivalent to your head falling from about 6ft (probably less due to the amount of body likely to hit the ground first). Forward speed has nothing to do with that (plenty of other problems from forward speed but they require motorcycle like body armour).

Unfortunately that's also why cycle helmets are not great in a crash involving a car / stationary obstacle etc.

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colinth [191 posts] 2 years ago
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There are just so many variables that we're never going to get the definitive answer. Personally, I always wear one. I can't believe there'll ever be an incident when I'll say "good job I wasn't wearing a helmet". I'm sure there are circumstances where it wouldn't help, but there are a whole host of ones where it would, try head butting the wall with and without a helmet. What we can't have is compulsion, its got to be personal choice

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Nzlucas [122 posts] 2 years ago
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http://www.bicycling.com/senseless/

Have a read of this if interested. Talks about various impacts and why the stats don't stack up.

Also goes into why innovation in the helmet market doesn't move at the same pace as other areas. Ie Bikes.

C

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stumps [3184 posts] 2 years ago
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I wear one and always will, however like others i agree its down to the rider's choice.

Everyone can come up with stories of how it did or didn't save them and thats all they are, stories, not medical facts, because we cant go back, recreate the scenario, and prove either way.

Doing what i do i can honestly say it would be an absolute nightmare, if it became law, to try and enforce it.

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kie7077 [833 posts] 2 years ago
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Good grief, unscientific anecdotal evidence means nothing, it's proves nothing, stop with it already. All these people who had crashes with helmets on are proving nothing because they don't know how they would have fared otherwise. I've had several head injuries in my life without a helmet, I'm not brain-damaged and I'm not dead, this also proves precisely nothing.

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Actium [38 posts] 2 years ago
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colinth wrote:

There are just so many variables that we're never going to get the definitive answer. Personally, I always wear one. I can't believe there'll ever be an incident when I'll say "good job I wasn't wearing a helmet". I'm sure there are circumstances where it wouldn't help, but there are a whole host of ones where it would, try head butting the wall with and without a helmet. What we can't have is compulsion, its got to be personal choice

Yes, I think this is why the pro-helmet side of the debate always feels that they can play the "common sense" card. Take the study that showed that motor vehicles overtake helmet wearers 6 inches closer then the bare-headed cyclist. If a lorry narrowly missed me and the wing mirror passed by within 6 inches of my bare head I am unlikely, as you point out, to say "good job I wasn't wearing a helmet", but technically I should. Equally when James Cracknell was bashed by a wing mirror when he was wearing a helmet, he "should" have come away cursing helmets, but instead he seems to be pro-compulsion now.

btw - I do almost always wear a helmet (when cycling anyway), but like others I think compulsion would be a very bad thing.

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Kapelmuur [293 posts] 2 years ago
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Most of us when riding our best bikes and wearing lycra wear a helmet because that's what our heroes on Eurosport do, it's the look of a 'serious' cyclist.

I've used the comparison with cricket before, there's no need for Sunday afternoon players to wear helmets but Cook, Pietersen et al do and folk like to look the part.

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colinth [191 posts] 2 years ago
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Actium wrote:
colinth wrote:

There are just so many variables that we're never going to get the definitive answer. Personally, I always wear one. I can't believe there'll ever be an incident when I'll say "good job I wasn't wearing a helmet". I'm sure there are circumstances where it wouldn't help, but there are a whole host of ones where it would, try head butting the wall with and without a helmet. What we can't have is compulsion, its got to be personal choice

Yes, I think this is why the pro-helmet side of the debate always feels that they can play the "common sense" card. Take the study that showed that motor vehicles overtake helmet wearers 6 inches closer then the bare-headed cyclist. If a lorry narrowly missed me and the wing mirror passed by within 6 inches of my bare head I am unlikely, as you point out, to say "good job I wasn't wearing a helmet", but technically I should. Equally when James Cracknell was bashed by a wing mirror when he was wearing a helmet, he "should" have come away cursing helmets, but instead he seems to be pro-compulsion now.

btw - I do almost always wear a helmet (when cycling anyway), but like others I think compulsion would be a very bad thing.

I don't place too much weight on that study, it was a one off and could have just been a study of particularly moronic drivers. It's driver education and law enforcement that are the key issues as we probably all agree. I nearly put my foot through the TV a few months ago watching one of the hospital soap things when someone was delivered to the casualty. Paramedic reported the cyclist wasn't wearing a helmet, so the "doctors" stood there shaking their heads, they might as well have said "serves him right then". Only a soap I know but thats the attitude we've got to avoid

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kie7077 [833 posts] 2 years ago
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Nzlucas wrote:

http://www.bicycling.com/senseless/

Have a read of this if interested. Talks about various impacts and why the stats don't stack up.

Also goes into why innovation in the helmet market doesn't move at the same pace as other areas. Ie Bikes.

C

Good article, it's crazy that helmet makers daren't mention safety in their advertising for fear of being sued. And the small if any increase in safety is outweighed by the fact that drivers will pass closer if you're wearing a helmet, 25% of cyclist deaths are caused by drivers that drove too close.

It does look like helmet innovation is on the move again though after decades of stagnation.

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Richard Hallett [14 posts] 2 years ago
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Tom Amos wrote:

If I'm doing a stage of the tour de france and reaching speeds of 80kmh, I'll wear my helmet. If I'm cycling to the shops to buy a pint of milk, I won't. End of debate.

Wonderful logic. Regular cycle helmets are designed to ameliorate the effects of impacts of just over 12mph, ie. the speed at which you might cycle to the shops to buy a pint of milk

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egb [43 posts] 2 years ago
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Having binned a few from landing on my head mountain biking, I can safely say they've kept me from serious injury on more than one occasion. If it came to me sliding down the road with my unprotected head or a helmeted head bashing against it, I'd take the helmet every time.

Helmets might not be sexy but serious head injury is even less so.

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Darren C [104 posts] 2 years ago
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The report just boils down to:
Everyone is different, and every accident is different.

I personally always wear a helmet, but it is up to each individual to make their own decision, based on their own perceived risk of injury.

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burtthebike [169 posts] 2 years ago
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Tripod16 wrote:

I believe the pro-peloton are the crash test dummies...  26

And has the death rate for them gone up, down or stayed the same since helmets were made compulsory for racing?

The only evidence I've seen suggested that the risk has gone up, not down, since the rules were changed.

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burtthebike [169 posts] 2 years ago
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Tom Amos wrote:

If I'm doing a stage of the tour de france and reaching speeds of 80kmh, I'll wear my helmet. If I'm cycling to the shops to buy a pint of milk, I won't. End of debate.

And you don't seem to understand a single thing about cycle helmets "end of debate" or not.

They are tested to about 20kph, so might just be effective for a low speed trip to the shops to buy a pint of milk, but at 80kph the forces involved are so outside the limits of their design that they are useless. In fact, they increase the danger from rotational injury, which is far more dangerous than direct impact.

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Not KOM [79 posts] 2 years ago
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I came off my bike on a wet tramline this morning, nicely smearing myself across an empty road.

I have no idea if my helmet helped or otherwise, but I don't have a headache now, at least  1

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burtthebike [169 posts] 2 years ago
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Ham-planet wrote:
kie7077 wrote:

Bicycle helmets are only rated for 12mph, question is, how effective are they at 20mph, 30mph, 40mph etc?

Your forward speed has little to no bearing on the effectiveness of a bicycle helmet, providing it has an appropriately low friction exterior.

This statement is only true if your forward progess is not halted by an immovable object, like a tree, a rock, a motor vehicle, a brick wall or a kerb. I would suggest that in a majority of collisions, this is going to happen, and that it is comparively rare for a collision to occur where the cyclist is not stopped in such a manner. Therefore, your forward speed is relevant, or are you suggesting that in all cyclist collisions, the only force retarding forward movement is friction? Which would be absurd.

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ribena [174 posts] 2 years ago
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I wear one simply because i fear if i don't, i'll get blamed for any head injuries should a motorist drive into me.

Making helmets compulsory seems to be solving the wrong problem here....

I also worry we're heading the same way with "hi-viz" jackets and the like.

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sim1515 [141 posts] 2 years ago
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burtthebike wrote:
Ham-planet wrote:
kie7077 wrote:

Bicycle helmets are only rated for 12mph, question is, how effective are they at 20mph, 30mph, 40mph etc?

Your forward speed has little to no bearing on the effectiveness of a bicycle helmet, providing it has an appropriately low friction exterior.

This statement is only true if your forward progess is not halted by an immovable object, like a tree, a rock, a motor vehicle, a brick wall or a kerb. I would suggest that in a majority of collisions, this is going to happen, and that it is comparively rare for a collision to occur where the cyclist is not stopped in such a manner. Therefore, your forward speed is relevant, or are you suggesting that in all cyclist collisions, the only force retarding forward movement is friction? Which would be absurd.

Your suggestion that forward progress is going to be halted in the majority of cases is fairly sensible (although just a suggestion as there are no facts to back that up) but it would really only be relevant in terms of helmets if it was in fact the helmet which hits the immovable object first which seems less likely to be the majority of cases.

Obviously a crash could result in going head first into an immovable object (and I'm not sure it's that impact which the helmets are designed for) but it seems more likely another body part will hit the object and the head will hit the floor (which I think they are designed for). In the latter case, you may still end up with some broken bones but you may be saved from having a gash on your head as well.

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SteppenHerring [322 posts] 2 years ago
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The debate, though, is about compulsion. Should it be a criminal offence to ride without a helmet - say a policeman catches you checking your latest fettling in the road outside your house or popping to the offie for some isotonic sports beer.

I wear one most of the time - it's nice to go without on a hot day when you're having a leisure ride with people you know and trust. I make sure my son always wears one - he destroyed the last one at Cyclopark without any internal or external damage to his head. Yes they do offer protection but making them compulsory is a big step.

PS: How many pedestrians suffer head injuries? A couple of years back, outside the office an iPed stepped in front of a moving bus and headbutted it. If he'd been wearing a helmet then they might not've needed the ambulance.

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