Mar 11, 2013

Do mandatory helmet laws deter children from cycling?

A new US study compares cycling by children in States with helmet laws against those without. It concludes the laws reduce children's head injuries but do it by reducing cycling. But is it convincing?

Alan Davies — Editor of The Urbanist

Alan Davies

Editor of The Urbanist

The historical perspective on cycling in Australian capital cities. Mandatory helmet laws for cyclists were introduced in most States in the early 1990s (red line). Shows mode share of metropolitan travel in Australia (kms of travel). Source: DoIT, Draft report on Walking, Cycling and Access to Public Transport.

A new paper on the effects of mandatory bicycle helmets on cycling by children and teenagers in the US has created a lot of buzz among those interested in this arcane and contentious subject.

The headline finding is the mandatory helmet law is associated with a 13% reduction in head injuries for 5-19 year olds. But it’s also associated with a 9% reduction in cycling by this age group.

The authors go further with the novel contention that helmet laws are also associated with an 11% increase in injuries among 5-19 year old users of skateboards, roller skates and scooters (although the absolute numbers are much smaller).

The study’s been tweeted by a number of respectable academics, implying it’s a serious paper with important findings. I suspect most of them have only read the abstract (although Robin Hanson appears to have read more).

The study, Effects of bicycle helmet laws on children’s’ injuries, was done by Pinka Chatterji of the State University of New York at Albany and Sara Markowitz of Emory University in Atlanta.

They capitalised on the fact that 21 US States have introduced compulsory helmet laws for children since 1987. They examined bicycle-related injuries over a total period of 17 years at a sample of 141 hospitals in 42 States, including 16 States with helmet laws.

This is a complex exercise, as States introduced laws at different times. Moreover, there are multiple age cut-offs across the States examined in the study – under 5, 9, 12, 13, 14, 15, 16, 17 and 18 years of age.

Exactly how the researchers went about their task isn’t as clearly expressed as it should be, but from what I can make out, they started with a hospital-level data base of injuries associated with consumer products.

They compared injuries in the year before the law was introduced in each state with those in the year after (there are multiple dates and cut-offs in some States). They compared these findings with what happened in States that have no helmet laws.

They infer the change in cycling by distinguishing between head and non-head injuries from bicycle-related accidents. All this data is fed into an aggregate model that also includes other variables like differences in weather and average income between States.

I’ve seen a range of comments on the paper, most of them taking it as evidence of the dangers associated with over-enthusiastic regulation.

But I’ve also seen some more critical comments:

  • The paper isn’t peer-reviewed (it’s an NBER working paper).
  • The methodology doesn’t account for serial correlation.
  • The total number of head injuries sampled across the period is very small, possibly as few as 250 and no more than 500.
  • Cases where helmets prevented head injury and therefore generated no hospital record aren’t (fully) accounted for.
  • Differences between States aren’t adequately accounted for. The population of States that legislate mandatory helmets may have different values (e.g. liberal) to those that don’t (e.g. conservative).
  • Some of the measures of State differences are very crude e.g. annual vehicle miles per capita at the State level is used to measure vehicle volumes.
  • The level of compliance with the law isn’t accounted for; nor is the extent of helmet-wearing in States with no law.

Some of these are limitations rather than shortcomings. It would be very difficult, for example, to measure directly, or in some way satisfactorily account for, the level of helmet-wearing in different places.

The authors note the penalties for non-compliance with the laws in helmet States are minor and there’s wide variation in the level of enforcement – some don’t enforce them at all.

Nevertheless, lack of information on the extent to which helmets are worn, or not worn, significantly reduces the value of the study.

Putting aside any caveats about the methodology, the authors make an important point. They say there are three possible explanations for the identified 13% reduction in head injuries.

One is that more riders wear helmets and enjoy the protective effect. Another is the law means fewer children cycle i.e. the deterrent effect of making helmets mandatory.

A third possibility, though, is that children are cycling more safely due to the publicity associated with the introduction of the helmet law. This explanation is especially interesting in light of the debate in Australia.

It suggests that it might be the heightened perception of danger that’s more important than the helmet law per se e.g. fearful parents don’t permit their children to cycle to school even with a helmet.

This could be the basis of an argument that the helmet laws aren’t necessary. Or it could be used to argue that repealing the law would make little difference.

The authors, however, conclude that the deterrent effect is the key explanation.

Our evidence in support of the decrease in ridership theory comes from the observed increase in injuries in other wheeled sports that is associated with the bicycle helmet laws.

They argue that helmet laws may induce “a substitution effect away from bicycle riding towards the other wheeled sports”.

It’s an interesting correlation but their justification is cursory at best. There are other explanations to check out first e.g. perhaps the hospitals sampled in helmet law States are, on average, in more urban settings that present riskier conditions for skate boarders?

I’m a little surprised some anti-helmet law advocates are publicising this study. The estimate of a 9% reduction in cycling due to helmet laws is modest compared to claims of a 30-40% reduction among children in Australia when the law was introduced.

Smith and Milthorpe and Finch, Heiman and Neiger reported much larger falls than 9% among children and teenagers in NSW and Victoria respectively in the first year following introduction of the law (with much smaller falls among adults).

Taking the study at face value, it’s worth asking if a 9% reduction in cycling is justified by a 13% reduction in head injuries. That would depend in part on the severity of the head injuries and on what those children/teenagers who are deterred from cycling do instead (skate-boarding?).

I think all those involved in the debate on the mandatory helmet law in Australia should be cautious about how much weight they give to these findings.


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29 thoughts on “Do mandatory helmet laws deter children from cycling?

  1. RidesToWork

    Comparison of infrastructure costs between freeways and cycling: For cycling, there’s some useful information at:

  2. Alan Davies

    Burke John #27:

    Alan has the Urbanist treated a comparison of infrastructure costs between freeways and cycling in detail somewhere?

    No, but it’s an interesting question and so I will. It’s certainly been mentioned by others in comments before, though, citing the high BC ratios of cycling infrastructure relative to freeways.

  3. Burke John

    Kathy thanks for raising the question of who exactly lobbied who for the introduction of these laws in Australia. Were ER docs in Queensland lobbied by helmet manufacturers? Heaven forbid.

    In Europe though it seems to be car companies, but the cat is already out of the bag there and the spell is broken. Cars are considered dangerous, not bikes.

    I was in Cairns when MHL were mooted. Not a soul I knew thought it possible they would be enacted.

    Alan has the Urbanist treated a comparison of infrastructure costs between freeways and cycling in detail somewhere?

    Btw, helmet costs should rightly be placed in the credit column of motoring infrastructure as they are actually paid for by cyclists.

  4. Krammer56

    I always love the MHL debates – so much passion and so little real clarity (which I suspect is Alan’s main point).

    Frankly I don’t care much one way of the other. It smacks of just another nanny-state approach to deciding what is good for you, but so do many road safety initiatives that have helped reduce the Victorian road toll from 1061 in 1970 to 282 last year – despite annual vehicle travel rising from 20.5 billion km to over 57 billion km.

    That said, having been involved in road safety and bike planning for 30+ years on and off, I wore a helmet long before they become compulsory. And after 50+ years of cycling I managed to smash my helmet on the road late last year with my head inside it. I am very glad I was wearing a helmet and will continue to do so.

  5. Kathy Francis

    Alan, don’t underestimate the part that was likely played by commercial interests in creating a perception that cycling was dangerous and the helmet was the solution. Helmet manufacturers Rosebank were involved with the development of the law in Victoria. They took out large ads in local papers letting everyone know that helmet laws were needed and on the way. Beyond this, the part they played is guesswork on my part but I would appreciate anyone who remembers more, contributing this information.
    Living in a rural Victorian town where no-one wore a helmet in 1989 we did not believe sych a law would ever pass the parliament. There was no perception of danger. Two years later there were no cyclists in my town.

  6. RidesToWork

    I was just trying to “imagine” how you would deal with two counteracting effects – safer roads, lower urban speed limits etc and reduced safety in numbers.

    The SN effect isn’t linear, but Jacobsen’s work doesn’t provide any indication of a threshold, and the shape of the curves looks very like the ‘Smeed’s Law’ curves.

    Was the “pressure” from Qld ER doctors in the 1908s due to lack of infrastructure, or because kids were falling off their bikes in the same way that kids in Amsterdam and Copenhagen also fall off their bikes?

  7. Alan Davies

    RidesToWork #22:

    I think you “imagine” what I’d say because you see the debate in terms of “whose for” and “whose against”. That kind of black and white perception is common with staunch advocates of almost anything. Some of us, though, aren’t “invested” in the issue.

    BTW, there was pressure in Qld in the 80s for action coming from ER doctors treating children with head injuries.

  8. RidesToWork

    Oh dear, I can imagine what you you’ll say!!!!

    The roads are a whole lot safer than they used to be, because of 50 km/hr speed limits and greater emphasis on RBT. Pre-law in 1989, 159 pedestrians were killed on Victoria’s roads, compared to 35 in 2012, a 78% reduction.

    The fall for cyclists isn’t quite so impressive, but nonetheless safety has improved, despite the fall in cycling. That doesn’t refute safety in numbers – it’s one factor of several (including speed limits, fines for irresponsible road use, booze buses etc) that contribute to overall road safety.

    As for the “perception emerged in the late 80s that cycling was dangerous and hence some agitated for MHL” – is there any evidence for this? Cycling was increasing and becoming a whole lot safer, e.g deaths and serious injuries per 10,000 regular cyclists fell from 5.6 in 1982 to 3.8 in 1989. If there was a perception about cycling becoming dangerous, I suspect it was limited to parts of Melbourne.

    The rest of the country ended up with helmet laws because they were forced on the other States under threat of having road funding withdrawn.

    Where is the evidence that the 10,960 people cycling to work in Ballarat, Geelong, and everywhere in Vic apart from Melbourne in 1986 – 4.6% of the workforce – suddenly got scared and started calling out for helmet laws? As you know, by 1991, numbers cycling to work in these areas had fallen by 43% to 6,266 – looks to me as if the helmet law was the real issue, and that current concerns about safety did not start until after campaigns were initiated to portray cycling as dangerous in order to persuade cyclists that they needed to wear helmets.

  9. Dylan Nicholson

    Well I agree Australia never really had cyclists in enough numbers to make it properly safe before MHL. But I can’t see how it will ever grow to the required numbers (and I’d be guessing we’d need somewhere around 10% of trips for drivers to accept cycling as a mainstream activity and be actively aware and cautious/respectful towards cyclists, primarily because most of them cycle themselves at least occasionally) as long as we have the strict enforcement and absurd fines associated with MHL currently.

  10. Alan Davies

    Dylan Nicholson #19:

    And repealing the law will make cycling safer, if it’s part of the move to get more people out of cars and on to bikes.

    I’d like to investigate the “safety in numbers” thing further one day. Some interesting questions: is it step-change phenomenon or continuous? What is the threshold for significant benefits? How safe was cycling pre-helmet law compared to today?

    Re regional areas, the point I’m making is a perception emerged in the late 80s that cycling was dangerous and hence some agitated for MHL. Perhaps it had less impact in “the country”, but most of regional Australia then, as now, lived in urban areas (e.g. Newcastle, Bathurst, Lithgow, Dubbo, Lismore, Albury, etc etc) so it’s reasonable that the argument had as much, or nearly as much, impact there too.

  11. Dylan Nicholson

    Alan, RidesToWork’s point was specifically about rural areas where there was no real perception that cycling was unsafe.
    I’d agree that repealing the law is unlikely to convince those of us that have grown up with the law in urban areas that cycling is now safer, but it could certain have an impact on future generations. And repealing the law will make cycling safer, if it’s part of the move to get more people out of cars and on to bikes.

  12. Alan Davies

    RidesToWork #16:

    Persuading cyclists to wear helmets means you have to portray cycling as a highly dangerous activity. Spending money on infrastructure won’t fix this problem.

    And you think removing the mandatory helmet law will persuade would-be cyclists it isn’t dangerous? I don’t – the helmet law was a reaction to a perception that cycling is dangerous, not the other way around. Perhaps there’s still a case for repealing the law on other grounds, but infrastructure and driver regulation are the way forward if the objective is to increase the level of cycling significantly.

  13. Burke John

    Rides to Work #15 the helmet and RBT issues have more in common than you indicate. Both are designed to remove any blame from the car and to diffuse it to the human or the cyclist in the other case. (In car culture the cyclist is often considered a sub-human than can be run over in anger)

    In statistics and polls all is dependant on the framing of the question. Cleary the introduction of RBT in NSW has drastically reduced road accidents. Has the introduction of RBT in NSW killed more people than it has saved? Never heard of a study or even the qeuestion asked. I believe it probably has but we are not likely to find out the truth in the near future.

    The inexplicable support for MHL is easily explained by the explicable addiction to car culture.

  14. RidesToWork

    Alan : “Provide the same level of subjective safety in Australian cities as riders feel in Copenhagen and the demand for helmets would fall and the law would be widely seen as an anachronism.”

    I agree with Kathy. I know plenty of places here where it feels safer to cycle than in Amsterdam. Yet these are precisely the places where cycling has been decimated since helmet laws.

    In the 1986 census, cycling to work in regional Victoria (everywhere except Melbourne) was 4.6%. This was increasing – from 3.4% in 76, 4.4% in 81 to 4.6% in 86. The much higher levels than in Melbourne (1.15% in 86) suggests that regional Victoria didn’t have the same barriers to cycling as Melbourne.

    The came the law. Cycling to work in regional Victoria fell from 4.6% (86) to 2.9% (91), 2.1% (96), 1.8% (01) and 1.6% (06). With a 48% reduction in teenage cycling (1293 counted pre-law, 670 a year later in Melbourne), we’d expect a continued decline in cycling to work, as teenagers who were discouraged from cycling by helmet laws joined the workforce over the next decade.

    Was cycling really that much safer in 1986, when 4.6% cycled to work in regional Victoria, even in the middle of winter? Or has our perception of safety been changed? Persuading cyclists to wear helmets means you have to portray cycling as a highly dangerous activity. Spending money on infrastructure won’t fix this problem.

  15. RidesToWork

    The Melbourne surveys of teenagers are quite revealing:
    Pre-law (May 1990) 1293 teenagers, 272 wearing helmets
    Post-law (May 1991) 670 teenagers, 302 wearing helmets.

    So 632 fewer teenagers were observed cycling. If some of them took up skateboarding that would probably be a good thing, even if a few of them ended up with head injuries. There might indeed be other explanations for an increase in head injuries, but it seems rather pointless to speculate when the blindingly obvious is staring you in the face. The effect 1) happened only in helmet-law states and 2) coincided with the introduction of the bike helmet laws. There could be other explanations, are they likely?

    Alan appears to be getting mixed up with the case-control studies that compare groups of often middle class children wearing helmets and riding on bikepaths accompanied by their parents with more deprived kids riding bikes on city streets and in some cases showing off doing tricks in front of their peers. In such studies, there are many possible explanations for the difference in head injury rates and highly complex statistical procedures are needed to separate out the confounded effects. There are several examples where such methods have totally failed, and researchers have been led to completely erroneous conclusions.

    But for cause-and-effect studies, such as the introduction of random breath testing in NSW – see – the effect is so obvious that I’d be wondering about the ulterior motives of anyone who questioned that the RTB law was responsible.

    The same is true head and non-head injuries in Victoria – the effect of the law on non-head injuries (in conjunction with the observational surveys) is only too obvious.

    It would be natural to expect something similar to happen in the US, but to a lesser extent, given their much lower level of enforcement.

  16. Alan Davies

    RidesToWork #8:

    The researchers find a correlation between helmet laws and skateboard injuries. I’m saying that before accepting (esp on the basis of one or two studies) that skateboards must be a good substitute for bicycles in helmet law States, consider if there might be other explanations that aren’t accounted for in the study design.

  17. Last name First name

    Alan parker OAM.

    Discussion about bicycle need to to seen in a broader context than bicycle helmets.
    Since the early seventies a lot of bicycle plans, with safety education, enforcement law make to change cyclist and motorist behaviour. Cycling in the Netherlands is far safer
    because for 35 years pedestrian and bicyclist safety in the Netherlands have had a much higher priority. In the 1990’s that priority has been reinforced by a whole range of integrated planning measures created in the Dutch Bicycle Master Plan in 1996 to create a more sustainable and safer transport system providing new bicycle infrastructure. The main feature of this plan, is the very low percentage of bikelanes compared to bicycle paths (Wellemen 1999). Of most relevence to Melbourne is the fact that Dutch bike lanes are only put on roads with a 50 Km/hr speed limit. The residential speed limit is also 30 Hm/hr which has now been adopted by the European Parliament for the rest of the EU. I have always worn a helmet buy wearing a helmet is just one of the minor minor safty safety aid in Australia . The problem is that planners who do not ride are completely ignorant of of world best practice

    Pucher and Bueler (2008) note that Dutch planners “introduced considerable alterations to the streets themselves, such as road narrowing, raised intersections and crosswalks, traffic circles, extra curves and zigzag routes, speed humps, and artificial deadends created by mid-block street closures. Cycling is almost always allowed in both directions on all such traffic-calmed streets, even when they are restricted to one-way travel for cars. That further enhances the flexibility of bike travel.”

    There is now a supportive national road safety policy which results in fewer road users being exposed to collisions that produce death or crippling injuries. Furthermore, the most advanced form of traffic calming — the 6500 “woonerf” imposed even more restrictions, requiring cars to travel at walking speed. This is rarely used as it is costly and the the 30Km/H. was introduced instead. Based on the public acceptance that pedestrians, cyclists, and playing children have as much right to use such residential streets as motor vehicles; indeed, motor vehicles are required to yield to non-motorized users.

    The Dutch car fleet has many more newer and smaller cars with rounder and softer fronts. The do not put bull bars on cars either. Bicycle friendly planning has reduced the number of pedestrian deaths in the Netherlands to 63 out of an urban population of 13.8 million. Compare this with the 196 pedestrian deaths in 2009 in Australia with a population of 20 million. In Australia there are 3 times as many pedestrian deaths in urban areas which is rather high given the population ratio.

    The “green tax laws” in the NEPP have also resulted in far fewer old cars, fewer four wheel drives and hardly any pedestrian crippling bullbars. (Parker, A A 2008) These pedestrian friendly features are particularly beneficial when cars are driven at much lower speeds in built up areas in which there is more rigourous traffic law enforcement.

    The larger trucks and commercial vehicles have EU standards for ‘side under run panels on them’ to prevent ped’s and cyclists going under the wheels.

  18. Dylan Nicholson

    Kathy, excellent post BTW. Even if you supported MHL in principle on the basis that it probably has the potentially to save a few lives here and there, there’s no way it can be supported in its current incarnation.

  19. Dylan Nicholson

    Plenty I could say on this matter, but just wanted to mention that I was down at Tidal River (Wilsons Prom) this long weekend and was quite pleasantly surprised to see how many kids (and their parents) have finally stop buying the idea that cycling is so dangerous it needs a helmet. Of the one or two kids riding along a sandy beach that did actually bother with their helmets, I could only think “only in Australia”.

  20. RidesToWork

    Anyone who doesn’t understand this paper model should look at the pre-and post-law head and non-head injury data in Victoria, at

    The effect of the helmet law sticks out like a sore thumb, with clear reductions in both head and non-head injuries coinciding exactly with the start of the law.

    In the case of Victoria, we also know that “bicycle use among teenagers had decreased by 43% by 1991 and by 46% by 1992, relative to 1990”. The same surveys also counted 29% fewer adult cyclists. We know there were fewer cyclists, so the drop in injury rates isn’t hard to understand. Based on what happened in Victoria, it isn’t hard to imagine why US helmet laws, even with much lower enforcement, had a similar, but smaller effect.

    Costs and benefits are best left to the economists. The NZ study estimated the savings at somewhere between 0 and 13 cents per year for every helmet that was purchased because of the law. That doesn’t even cover the cost of the helmets. The WA study was more generous, saying: “In monetary terms, it is unlikely that the helmet wearing legislation would have achieved net savings of any sizeable magnitude.” Again this is just the cost of the helmets (and a limited amount of police enforcement), ignoring the lost health and environmental benefits of reduced cycling

    So, when you add in the lost health and environmental benefits, reduced Safety in Numbers, and a possible increase in head injuries from other wheeled sports, it’s hard to imagine that helmet laws don’t cause more problems than they solve.

    Under normal circumstances, I’d expect laws that discourage a healthy, environmentally-friendly activity to require justification. The best estimate I have is that helmets laws might prevent 1 hospital admission for a head injury (not necessarily the reason for that admission) for every 10,000 cyclist years – That might be enough to persuade Alan to wear a helmet, but for people who don’t cycle to the corner shop because of helmet laws, despite needing the exercise, and are likely to die from a stroke or heart disease or complications of diabetes or obesity in the next 20-30 years, I would suggest that allowing them to chose would improve public health.

  21. RidesToWork

    “It’s an interesting correlation but their justification is cursory at best. There are other explanations to check out first e.g. perhaps the hospitals sampled in helmet law States are, on average, in more urban settings that present riskier conditions for skate boarders?”

    Alan, the analysis compares the change in injuries in US States that introduced helmet laws with those that didn’t. Cycling head and non-head injuries fell at exactly the same time as the helmet laws were introduced. Also at the same time as the helmet laws were introduced, head injuries for other wheeled sports increased.

    The analysis would not detect an effect if the hospitals sampled in helmet-law States were in more urban settings that present riskier conditions for skateboarders. That does that explain why head injuries for other wheeled sports increased (and cycling injuries decreased) at exactly the same time as helmet laws were introduced.

    The NYC report you cited not long ago reports surveys in which only 14-20% of High School Students said they wore a helmet even once during the past year. In the context of these low proportions of children obeying the helmet laws, a 9% reduction cycling is indeed a big effect.

  22. Burke John

    MHL discussions are like beer and sex. Just when you are over the boredom and want more, there is more!

    Alan seems to intimate that very little can be settled so far by way of studies or parading of statistics and I’m inclined to agree.

    All argument is though is held according to the conventions of road safety doctrine which says cars should go as fast as possible without impediment up to an acceptable level of loss of human life.

    My own interest is the environment and also happiness at large in society but I’ll stick to “road safety” issues, as I would to the missionary position and lite beer if that was all that was available.

  23. Kathy Francis

    Alan, I can’t agree that this is what is going on here. Worldwide helmet laws are already an anachronism. Here they should be widely regarded as (1) punishment and (2) revenue raising. The enforcement of the helmet laws bears little relationship to ‘fears about the safety of cycling on roads’ and everything to do with targeting a soft minority who are easy to fine.
    Most cycling situations in Australia are actually not that different from those in most of Denmark. The targeting of cyclists occurs on off-road biketrails, suburban streets, quiet country roads the wide empty streets of rural towns. In these places no-one was afraid of head injury until a concerted advertising campaign told them it was dangerous. The ‘same level of subjective safety’ already exists. There is no hope of infrastructure ever being delivered to these places.
    Further , to link the end of MHL to the development of infrastructure in Australian cities is to continue the punishment of cyclists indefinitely. The budget for new cycling lanes was this year reduced to zero while the helmet fine was increased to $176. To put this another way, the penalty for riding on an off-road bike track with the helmet strap untied is the same as the fine for speeding in a motor vehicle. And this IS being enforced. To continue the punishment of cyclists in this way is no different to punishing women by keeping them indoors because there are no laws protecting them from assault.
    As you have noted elsewhere the majority of motorists would never put up with this level of petty harassment , hence no car helmets.

  24. Alan Davies

    Nik Dow #4:

    Helmets are primarily a symptom of fears about the safety of cycling on roads. Provide the same level of subjective safety in Australian cities as riders feel in Copenhagen and the demand for helmets would fall and the law would be widely seen as an anachronism.

  25. Nik Dow

    Helmet law is not an “arcane” subject. It directly affects the lives of many people, and reduces the contribution that cycling could make to health, environment and transport in Australia.

    I have read the whole paper. It is one more contribution to the subject overall. What is most interesting is that the pattern of this debate is split. In Australia we find some academics, most organisations claiming to represent cyclists and politicians strongly supporting the law, while in most other countries there is a lot more opposition to helmet compulsion. I haven’t found a significant overseas cyclists’ organisation that supports a helmet law. So something other than facts is operating here.

    London’s “cycling czar”, Andrew Gilligan, talking about the recent Mayoral announcement of a “step-change” in provision for cycling stated “I want cycling to be normal, not something you need special equipment or clothes for. In the Netherlands you see people cycling slowly, in ordinary coats, without helmets or hi-vis gear, because they feel safe. Cycling in London is still a kind of Darwinian struggle. That needs to change.”

    In other words, you can either aim to make cycling safe, in which case many people will do it, or accept that it is a “Darwinian Struggle” in which case few will do it.

    Australia is still stuck in the Darwinian mentality.

  26. Alan Davies

    Scott #1:

    This is a fairly specialist forum and quite a lot of readers are interested in cycling, incl the whole MHL thing. I agree though that the amount of attention MHL gets in the popular media is miniscule.

    Strewth #2:

    ….it seems to me the standard of evidence in this study is similar to that in all the other studies that conclude mandatory helmets are effective at preventing head injury.

    Which other studies are you comparing it against?

  27. Strewth

    Actually Scott at #1, it may be that helicopter parents are already being deterred by mandatory helmets from letting their kids cycle, because it sends a signal that cycling is as dangerous as motorcycling because these are the only two modes of transport that require mandatory head protection.

    As far as the US paper goes, the important finding is not so much the absolute reduction in cycling (Australia’s law was very strictly enforced everywhere in 1991-92, the US ones not so much), as the fact that the reduction in head injuries is of the same order of magnitude as the reduction in cycling. Which means you don’t need to bring in any other factors to explain the drop in head injuries after the law.

    Now of course if one’s focus is solely on preventing head injury then one could readily be persuaded it would be for the best if people didn’t ride bikes so much, provided the substitute activities are lower risk. (Sitting on the couch watching TV is associated with a very low risk of head injury.) I seriously think that might have been part of the inspiration for mandatory helmets in Aus/NZ twenty years ago: the people urging them on were almost exclusively non-cyclists with no direct insight into how safe or dangerous cycling is as a day-to-day activity, but a lot of selective experience with seriously head-injured cyclists. They could prejudge that all the head-injuried motorists and pedestrians must be exceptional cases, because driving and walking are things they did themselves and so must be inherently safer.

    Of course we shouldn’t confuse correlations with causality, but it seems to me the standard of evidence in this study is similar to that in all the other studies that conclude mandatory helmets are effective at preventing head injury.

  28. Scott

    I look at this argument (regarding helmets and cycling) and am amazed by the amount of discussion put into it. It doesn’t get any more “elitist” than this in my opinion.

    As for my two cents, the reason for a reduction in cycling in school aged kids is pretty clear.

    1. People are living further away school
    2. Parents are more protective of their kids than they used to be (because we have less of them)
    3. Cars are cheaper than they used to be
    4. Kids are fatter than they used to be
    5. More entertainment options available for kids now

    Will getting rid of the helmet law have any impact on these things? Doubtful. If anything, it might further prevent “helicopter parents” from introducing their kids to cycling. Be careful what you wish for.

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