Study: Helmet laws & bicycle use

Alan @ EcoVelo points me to a study recently published in the journal Injury Prevention showing that provincial helmet laws have no impact on bicycle ridership in Canada.

One of the more common arguments against mandatory helmet laws used by I and others is that mandatory helmet laws discourage bicycle riding. This Canadian study, however, compares cyclist mode share between 2001 and 2007 in the two provinces that implemented mandatory helmet laws versus the other six that didn’t and saw no difference.

I interviewed one of the study authors, Jessica Dennis. She completed her MSc in epidemiology at the University of Ottawa.


Do you and the other researchers have a personal interest in the topic? Are you cyclists? And do you wear helmets? :-)

Two of us are cyclists and yes, we always wear helmets! I’ve been in a few collisions during my bicycling career – enough to make me never want to ride without a helmet. I became interested in this project when I came across an article arguing that mandatory helmet laws would discourage people from bicycling. I was so surprised at how often this argument was used, despite little evidence to this effect, that I decided to get involved.

Doggie helmet

Your research shows helmet use is higher for children when helmet legislation applies to all ages vs only children.  Do you have any thoughts on why this might be?

As we hypothesize in our article, this could be because fewer adults are role-modeling this behaviour. A 2005 study of bicyclists in Toronto, Canada found that 95% of children riding with a helmeted adult wore helmets, compared to 41% of children riding with a non-helmeted adult (Khambalia et al. 2005). Enforcing a helmet law that only applies to youth could also be more difficult than enforcing a helmet law that applies to all cyclists. I imagine it would be hard for a police officer to distinguish a non-helmeted 16 year old cyclist who should be ticketed from a non-helmeted 19 year old cyclist who is exempt from the law.

(Khambalia A, MacArthur C, Parkin PC. Peer and adult companion helmet use is associated with bicycle helmet use by children. Pediatrics. 2005 Oct;116(4):939-42.)

Do you believe your research is reproducible in the United States? Would a similar study in the US have similar results?

I would love to see similar research conducted in the United States. A 1999 study in 3 NY City suburbs found results similar to ours in that they found that helmet use increased as more people were targeted by legislation (Puder et al, 1999). I think looking at this question on a larger scale would help us to better understand the benefits of helmet laws that apply to all cyclists.

Although bicycling culture differs from one country to another, I think the US and Canada are more alike than say, the US and the Netherlands. I think it’s reasonable to think that if helmet laws didn’t stop Canadians from cycling, then they won’t stop Americans from using their bicycles either.

(Puder DR, Visintainer P, Spitzer D, Casal D. A comparison of the effect of different bicycle helmet laws in 3 New York City suburbs. Am J Public Health. 1999 Nov;89(11):1736-8.)

You are undoubtedly aware of the Australian experience [D. L. Robinson 1996] and an earlier Novia Scotia study [LeBlanc,  Beattie & Culligan 2002]. Why does your meta-analysis draw different results? Are there other similar studies with results that match yours?

First of all, I often see the Nova Scotia study used as evidence that helmet laws discourage bicycle use. However this study was not designed to measure bicycle use so this conclusion absolutely cannot be drawn from this data. In fact, no conclusion on bicycle use can be drawn from this data. As LeBlanc (the study author) responds in a letter,

“The variations in collection methods are a far more plausible explanation for the variation in cycling rates and proportion of child cyclists than the legislation.” (LeBlanc, 2002)

We found that helmet laws did not cause people to abandon their bicycles. This is in line with a 2001 study by researchers in Toronto, Canada who found that introducing a child helmet law didn’t affect bicycle use among children 5-14 years of age (Macpherson et al. 2001).

I am aware of the Australian studies cited by D.L. Robinson. One of the big differences between the Canadian studies and the Australian studies is that the Australian studies only looked at bicycle use in the two years immediately following the introduction of legislation.

It’s unclear if the drop in bicycle riders was sustained or if it was a short-term effect of the legislation, or even if it was due to differences in how the study was carried out from one year to the other. The Canadian studies look at bicycle use in the several years following legislation, which gives a better overall picture of long-term trends in bicycle use.

(LeBlanc, J.C. Butting heads over bicycle helmets (author reply). CMAJ. 2002 Aug 20;167(4):338-9.

Macpherson AK, Parkin PC, To TM. Mandatory helmet legislation and children’s exposure to cycling. Inj Prev. 2001 Sep;7(3):228-30.)

Between 2001 and 2007 (your study period), bicycle use has exploded all over North America. Against this background, how do you measure if helmet laws inhibited bike use or not?

Our study looked at bicycle use before and after helmet laws were implemented in two Provinces. In addition, we looked at bicycle use over the same time period in the remaining eight Canadian Provinces. This is a major strength of our study. When we compared biking trends in the provinces that changed their helmet laws to the biking trends in provinces that didn’t change their helmet laws, we saw no difference. This tells us that helmet laws didn’t have an effect on whether or not people used their bicycles.

What is your opinion on police enforcement of bicycle helmet laws? Should police spend their resources on targeted enforcement of bike safety laws, such as helmet and other bike equipment laws?

Helmet laws are not meant to divert valuable police resources away from fighting crime. To me, the biggest benefit of helmet laws is that it normalizes helmet use. Most people are law-abiding citizens, and when a law is in place, they will try to obey it, regardless of whether or not a policeman is standing over their shoulder. The goal of helmet laws is to change bicycling culture, so that people don’t think twice about putting on a helmet – it will just be an accepted piece of bike gear, the same way that everyone buckles their seatbelts when riding in a car.


Thank you to Ms Dennis for her willingness to interact on this. This study will likely prompt a lot of discussion, but please keep it civil.

22 Comments

  • Mikael
    August 16, 2010 - 10:31 am | Permalink

    I've read the paper. Are we really supposed to take a study based on a household survey seriously? Give us some real science.

  • eriksandblom
    August 16, 2010 - 1:14 pm | Permalink

    I read somewhere that people in surveys overstate how much they use alternative transport. They might say they take the bus or ride a bike once a week, instead of driving a car. But really its just once a month. Sorry I don't have a source for it right now.

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  • Vanore+cycle
    August 16, 2010 - 1:46 pm | Permalink

    “Give us some real science.”

    Much of the debate on this issue, on both sides, uses personal opinion and anecdote – quite unscientific. I agree self-reported surveys aren't ideal, but it's far more scientific than what we had before, which was almost nothing. This study helps move the debate forward, and perhaps some sociologist somewhere will devise an observational experiment of high quality that can be used for comparison.

  • eriksandblom
    August 16, 2010 - 2:08 pm | Permalink

    Vanore+cycle, imagine if all the effort going into helmet studies instead went to counting cyclists. I mean, they know how many cars drive on every street in every city just about every year. Why can't they come up with reliable cycling data?

    I'd also like to know, how many cyclists get permanent brain damage every year? I asked the authorities here in Sweden and they don't know. Since the scare campaigns talk about permanent brain damage, you'd think they knew how many there are. Permanent brain damage is also the reason people wear helmets but not arm protection, for instance.

    But no. They don't have reliable numbers for that or for how much cycle traffic there is. But they do measure the percentage of cyclists with helmets every year.

    So… they don't know how many cyclists get hurt and they don't even know how many there are. They just know helmets the solution.

  • gearinches
    August 16, 2010 - 2:48 pm | Permalink

    Laws should exist to keep individuals from hurting others, not to save us from ourselves. I don't agree with helmet laws, and I can see how they'd hurt ridership in a college town like mine. I see hundreds of students riding to class, work, home, wherever daily, and most are helmetless. I think if they were forced to wear them, most would just choose to walk. Personally, I ride with a helmet on singletrack, but never on the road. It's my own choice, and I can take care of the bills should I injure myself.

    I love how the do-gooder society we live in is more concerned with restricting us from behavior that may have an immediate negative impact such as this and seat belt laws, but nothing is ever done to keep people from destroying themselves slowly. If you tell someone they have to eat vegetables and lean meat and get exercise, you're a Nazi, but telling us to buckle up or put on a helmet is a nice common-sense law.

  • Brent
    August 16, 2010 - 5:13 pm | Permalink

    I took a quick spin around a couple of helmet manufacturer's websites. It's interesting to see how much airflow is touted, but safety standards are hardly mentioned, and usually only in passing. The car companies, at least, sometimes give us videos of cars smacking into brick walls, with crash test dummies secured by whatever safety system the manufacturer has dreamed up. It's almost as if the helmet manufacturers themselves don't believe in their product. Can't we have something, anything, showing how safe the product is?

    After all, these are the manufacturers in whom we trust our heads.

  • Adrienne Johnson
    August 16, 2010 - 9:12 pm | Permalink

    There will never be “real science” on this issue because those who “study” the subject always seem to come to it with an agenda other than simple knowledge. The person in the article stated-

    “To me, the biggest benefit of helmet laws is that it normalizes helmet use. Most people are law-abiding citizens, and when a law is in place, they will try to obey it, regardless of whether or not a policeman is standing over their shoulder. The goal of helmet laws is to change bicycling culture, so that people don’t think twice about putting on a helmet – it will just be an accepted piece of bike gear, the same way that everyone buckles their seatbelts when riding in a car.”

    To what end do they want us to wear helmets? What part of the study shows the over riding benefit of helmet use? Does blind acceptance of “safety” gear mean that it is in fact “safe”? Of course not but that seems to be the hoped for outcome of the interpreted information.

    i wonder how many people in the areas with mandatory helmet laws would take them off if they could? Was the question even asked?

  • Brent
    August 16, 2010 - 10:21 pm | Permalink

    The nihilist in me wonders whether this study finds its conclusions in the few brave cyclists who still venture onto our car-ravaged streets, talismans worn atop, law or not. Comparing before and after numbers shows nothing, just as mandating shoe wearing would do little to increase the numbers of people who wear them.

  • Lee
    August 17, 2010 - 5:24 am | Permalink

    I think this study has little relevancy for any other country, as Canadians are perhaps the most law-abiding and polite people on the planet. They are the only people who would accept a helmet law and continue to ride in exactly the same numbers. This study would not apply to Australians, Americans, Europeans or probably anyone else either.

  • AnalRetentivesMustDie
    August 17, 2010 - 9:20 am | Permalink

    Where is this rash of head injuries that helmets are preventing? I wear my helmet and encourage others to do the same. But from a public health perspective, helmet laws are just asinine. Let's focus on the causes of crashes and injuries – wrong way riding, zooming out from driveways and sidewalks, riding without lights and reflectors at night, etc. If the self-appointed helmet cops would address these instead, we'd all be a lot better off.

  • August 17, 2010 - 9:32 am | Permalink

    A few questions that I don't think were answered in the study (though, I haven't read it – and, i guess, won't, unless it becomes public):
    1) was there helmet enforcement in the two provinces, PEI and Alberta? (i.e. i suspect new laws without enforcement do not change behavior.)
    2) did cycling rates grow in the non-helmet provinces, and did they grow as much in the two helmet provinces, PEI and Alberta? (i.e. did helmet laws slow the rate of growth of cycling in the two helmet provinces, even if it did not exactly decrease cycling rates?)
    3) how much of a role does cycling mode share, if any, play in the deterrent effects, if they exist, of helmet laws? (i.e. i would think places with very low cycling mode share — like Oz — would see very little effect of mandatory helmet laws, whereas places with 5% and up cycling mode share would see much more dramatic decreases in cycling when introducing helmet laws. this hunch may already be disproved by the Oz study.)

    and it's interesting that the authors have called into question not just the long-term effects of the Oz helmet laws, but also the integrity of the study itself — even for the two years for which it was conducted (“or even if it was due to differences in how the study was carried out from one year to the other”). if nothing else, it's gutsy to call another researcher's work bunk.

  • August 17, 2010 - 9:32 am | Permalink

    accidentally double-posted.

  • eriksandblom
    August 18, 2010 - 7:31 am | Permalink

    It's reasonable to assume that cycling in North America has been almost completely dangerised. Facts on the ground as well as perceptions keep almost everyone from cycling.

    A study from Portland, Oregon showed that 68% of residents were interested in cycling, but at the same time 60% think it's too dangerous. Seven per cent cycle because of the new infrastructure Portland is famous for, while 1% are “strong and fearless” and would cycle whatever the conditions.

    The study is called “Four Types of Cyclists” (PDF).

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  • Rootsid
    August 18, 2010 - 6:45 pm | Permalink

    To me it isn't relevant if helmet laws encourage or discourage bicycle riding. It's not even relevant if wearing helmets save lives (yes I always wear my helmet when I'm riding), the only thing that's relevant is that it's not the affair of government if I wear a helmet or not. It just isn't governments business.

  • Adrienne Johnson
    August 18, 2010 - 10:37 pm | Permalink

    I would say that there are a great deal more “accidents” that occur for those on bicycles because of poor driving of cars and substandard road design than lack of reflectors or lights or zooming off of sidewalks. If we are going to tackle the cause of urban bicycling dangers than we need to call it for what it is- too many cars, not enough design creativity in street creation and poor urban planning.

  • eriksandblom
    August 19, 2010 - 1:57 am | Permalink

    It's worth mentioning that the biggest pro-helmet study says that 90% of dead cyclists in the USA were killed in collisions with motor vehicles. Just to be clear, I doubt very much that a styrofoam hat will make a notable difference in a collision with a motor vehicle.
    Cochrane Review: Helmets for preventing head and facial injuries in bicyclists

  • November 2, 2010 - 1:27 am | Permalink

    Having lived in both Europe and Australia, I can tell you for a fact that helmet laws DO make a difference. I cycle far less here in Oz principally because of helmet laws. It is not nearly as enjoyable, comfortable or spontaneous if I have to carry a helmet with me if I choose to go to the park or the shops by bike.

    Yet I still ride a lot. Only in Australia, I just ‘race’ or mountain bike, both of which I would choose to wear a helmet for anyway given the choice. The cycling I don’t do here is utility cycling – riding a bike as a form of transport. Why – helmet laws make utility cycling unattractive.

    Helmet laws have little impact on people who ride for sport & fitness. This type of cycling is not about transport, its about competition, effort and sweating – mandatory helmets don’t impede this at all – which is evidenced by the increase in fitness cycling in Australia over the last 10 years. But this type of cycling is no different to playing football or going to the gym as it provides little social benefits (but lots of personal benefit).

    The type of cycling that we need to encourage, and that helmet laws discourage, is utility cycling. Riding as a method of getting from A to B. This is the type of cycling that social benefits are derived from – replacing motorised travel and making cities more people friendly.

    The issue here is not whether helmet laws decrease cycling, it is what type of cycling they have an affect on. If you support helmet laws and seek to impose your will on others, then the burden of proof is on you to show that helmet laws make cycling safer, and at an amount adequate to justify imposing on my freedom. They do not.

    The indisputable fact is that the safest places to cycle (Netherlands, Denmark & Germany) are also the places with the lowest helmet usage rates. And the contra is also true – the places where cycling is most dangerous relative to car usage (Aust, UK, USA) are also the ones with the highest helmet usage.

  • Anonymous
    December 11, 2010 - 11:36 am | Permalink

    There is now a critique of this study at cyclehelmets.org

    Cyclehelmets.org Commentary: The effects of provincial bicycle helmet legislation on helmet use and bicycle ridership in Canada
    Their ridership data are based on telephone surveys in which respondents were asked whether they had cycled in the last three months. If they had, they were classed as bicyclists. They were then asked how many times they had cycled in the last three months. This cannot be considered as robust data on ridership.

  • December 11, 2010 - 4:36 pm | Permalink

    Thank you Erik. I’ll take a look.

  • Thomas Bowden
    August 8, 2011 - 3:37 pm | Permalink

    Where is the outcry for mandatory driver and passenger helmets?  You want to save some lives, let’s “normalize” that behavior.  Why is it the government’s business to “normalize” a behavior (wearing a helmet) with so little demonstrable benefit?  I think our own US Government has done enough damage “normalizing” high carbohydrate diets without scaring every would be bike commuter into thinking that riding a bike on a quiet street is the equivalent of bungy-jumping with home-made bungy cords.  I’ve read lots of stats “prevent 85% of head injuries” etc. but there are major problems with all the statistics cited by both sides of the issue.  This tells me that, as usual, you can do a survey or interpret statistics to prove or disprove almost anything you want.  It’s easy to imagine accidents where a bike helmet might prevent injury, if you focus on it.  What is more difficult is to assess the unintended consequences and 2nd order effects.  It’s also easy to be lulled into false security when the truth is, most bike helmets have little or no protective value in the types of accidents that people fear (and die from) most – automobile impact – regardless of who is at fault. It’s pretty clear to me that if we put half the effort into promoting safe riding (with traffic, in the road, off the sidewalk, sober, in the daylight or, if at night with lights, at reasonable speeds, obeying (or at least “respecting” traffic signals), the “traumatic head injury” monster that everyone so fears would be put into perspective.

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