How to choose a bike helmet

Any activity with a large number of participants has its religious wars, pitting one group of true believers against another. Biking has plenty of these pointless, internecine battles, including, but certainly not limited to, roadies vs. mountain bikers, lovers of Lycra vs. wearers of wool, and posteriors on plastic seats vs. tooshes on tanned-leather saddles. Perhaps the loudest battle among bikers is the helmet wearers (“My helmet saved my life/How could you be stupid enough not to wear one?”) vs. the helmet free (“Helmets discourage biking/make me sweat/mess up my hair/look silly/are for wimps”).

I wear a helmet, but I’m not going to presume to say that everyone should wear one. (I bought my first helmet when I started biking in Manhattan and mixing it up with cab drivers in Midtown.) Physics and neurology seem, to me, anyway, to be on the side of wearing helmets, but the anti-helmet crowd can cite research to bolster their case. On the website of the Bicycle Helmet Research Foundation (BHRF), whose agenda you can spot at 20 paces while blindfolded, you can find a graph plotting the percentage of trips by bike in eight countries against fatalities per billion kilometers biked, along with the percentage of riders in each country who wear helmets. The results?

  • The countries with the smallest percentage of trips by bike and the largest percentage of helmet wearers have, in general, the highest fatality rate.

    Supposedly this means that wearing a helmet makes you more likely to die in an accident.

  • The countries with the largest percentage of trips by bike and the smallest percentage of helmet wearers have, in general, the lowest fatality rate.

    Then again, they also have superb biking infrastructure and have drivers who are much more accustomed to sharing the road with bikers, neither of which appears in the graph. It also probably doesn’t hurt that, in some European countries, a driver is automatically considered liable in an accident with a biker.

What does it all mean? Admittedly, my quick analysis skews toward wearing helmets, but it’s not mine to say; do what you’re most comfortable with. Note, however, that if you live somewhere that helmets are mandated by law (as I do) and you choose not to wear one, you may face the occasional ticket.

Now on to the subject of today’s symposium: if you decide to wear a bike helmet, how do you choose one? In the U.S, the answer to this question got a lot easier in 1999 when the Consumer Product Safety Commission (CPSC) started requiring that all helmets sold in the U.S. meet the same standard. The website of the Bicycle Helmet Safety Institute, the pro-helmet equivalent of the lobbying group mentioned above, is awash in useful information for folks who want to wear a helmet (plus oodles of clutter—they desperately need an editor and a graphic designer):

If you live in the Seattle area, the Cascade Bicycle Club offers free or inexpensive helmets.

Here are a few thoughts based on my last trip to the bike shop to buy a bike helmet, a couple of years ago, to replace a 10-year-old helmet that had seen a lot of use:

  • One brand of helmet fit me quite well while another brand didn’t fit worth a tinker’s damn, and even within the brand that fit well, some models were more comfortable than others. I don’t think one brand was of higher quality than the other, I just think they were made for heads of different shapes. Based on that experience, I’d recommend that you not buy a helmet online if you can help it, and that you try on every helmet of your size in the shop.
  • If you live someplace where the weather gets cold enough to want a stocking cap under your helmet, you may find it useful to get a helmet on which you can adjust the fit. (Stocking caps now come in very thin, warm materials, not just in bulky wool for folks who live in places where shallow lakes freeze solid in the winter.) Mine has a little dial in the back that I can rotate one direction or the other to loosen or tighten the fit for when I’m especially full of myself or when I want to wear a light cap under my helmet to take the chill off. With the size and number of vents in current bike helmets, temperatures in the 40s are plenty cool enough to make me want another layer.
  • If you ride after dark, you may be interested in a helmet that has a clip in the back for a rear bike light (sometimes known as a blinky butt light). Unfortunately, last I looked, there were no helmets that had both a size adjustment and a light clip. Ask anyway, just in case things have improved.

2 comments to How to choose a bike helmet

  • Greg

    What does it all mean?

    I think there are at least two questions here –
    1) What makes sense for me as an individual bike rider?
    2) What can we do as a society to make bike riding safer?

    On (1) I think the evidence suggests that helmets give you a small but probably measurable safety gain *if you don’t ride more aggressively* to compensate. In other words you may want to wear a helmet but try to ride as if it doesn’t work 🙂

    On (2) it seems pretty clear that encouraging/requiring people to wear helmets doesn’t do much if anything to increase general safety. And more importantly, the vastly safer state of cycling in places where no one wears helmets (like the Netherlands) means that there are *much much* more effective ways to make cycling safer than promoting helmets. So focusing on adapting those things to the US seems like the way to go for serious safety advocacy.

    It’s also somewhat disturbing that no one has ever gotten substantial cycling in a country that does helmet promotion. Doesn’t mean it’s impossible, but certainly daunting that no one has ever done it. Given the massive health benefits of general cycling relative to the risk of injury, helmet promotion thus looks pretty dangerous from a public health standpoint. Perhaps the key here is to get motorists to wear them first (which is seriously a place where they would save far more lives than on bike riders) – and only after they are established for drivers move to suggesting them for other uses (eventually I can imagine people wearing them everywhere all the time.)

    Here’s an early attempt at looking at them for motorists (note the projections of hundreds of millions of dollars in risk reductions in just Aust. due to decreased head injuries):

    Disclosure – I wear a helmet when I ride in the US, but focus my safety advocacy elsewhere. If friends ask about them I say wearing one is probably good but that how you ride is at least as critical – likely much more so….

    • Good points, Greg. Thanks for pointing out the research on helmets for car drivers. If legislators truly want to make the world a safer place for transportation, they should start where the bigger payback is, both in terms of saved lives and in terms of profits for the helmet manufacturers who are lobbying for bike helmets.

      Over at, Dave Horton, a British sociologist, wrote a piece on the effects of helmet promotion campaigns:

      Do helmet promotion campaigns make cycling more or less safe, overall? There is evidence that cycling levels decline when helmets are promoted and collapse when they become compulsory (Liggett et al 2004, 12). Australia, the first country to make cycle helmets compulsory, witnessed a post-compulsion fall in levels of cycling of between 15 and 40 per cent (Adams 1995, 146). According to ‘the Mole’ (2004, 5), in Melbourne ‘compulsion reduced the number of child cyclists by 42% and adults by 29%’. Because cycling tends to be safest where there are many cyclists (Jacobsen 2003), and most dangerous in places with few cyclists, and because helmet promotion campaigns reduce the overall numbers of cyclists, helmet promotion increases the risk of cycling. The relationship between increased cycling and increased safety appears to be confirmed by the experiences of the Netherlands and Denmark, which have high levels of cycling, very low rates of helmet wearing, and low rates of death and serious injury among cyclists….

      I’ve also seen a discussion about the effect of a mandatory helmet law on a large-scale bike-rental program in Tel Aviv, akin to Velib in Paris. No one wants to wear a helmet that is damp from someone’s sweat or infested with someone’s lice, and no one carries a bike helmet around just in case they want to hop on a bike, so a helmet law would be the death of a rental program.

      Not to pile on or anything, but Environmental Health Perspectives, published by the U.S. National Institute of Environmental Health Sciences, recently published an article titled Do The Health Benefits Of Cycling Outweigh The Risks?, for which the answer is yes:

      For the individuals who shift from car to bicycle, we estimated that beneficial effects of increased physical activity are substantially larger (3 – 14 months gained) than the potential mortality effect of increased inhaled air pollution doses (0.8 – 40 days lost) and the increase in traffic accidents (5 – 9 days lost). Societal benefits are even larger due to a modest reduction in air pollution and greenhouse gas emissions and traffic accidents.

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