bike helmet use

Photo: Joel Wintermantle/Chicago Tribune

Active Transportation Alliance event, October 6, 2012

One side issue that's come up with Chicago's new bike-share program is that the Divvy bikes don't come with helmets. Either you bring your own or you go without a brain bucket. Eric Zorn's co-blogger Jessica Reynolds brought this up the other day, and questioned whether Divvy users would actually carry their helmets for use with the bikes. While I don't see carrying a bike helmet as much of a burden, it's true that bike-share users don't wear helmets very often, way less than cyclists generally.

Of course there's a handful of people who wear helmets religiously. But a study in Boston and Washington, published this week in the Annals of Emergency Medicine, found that helmet wearers account for barely half of all bicyclists and only a tiny minority of riders of shared bikes. In both cities, 4 in 5 of those riders went helmetless.

This, of course, freaks people out. But it freaks people out in America, where riding without a helmet is generally considered a terrible idea even if it's not universal. Reynolds, for example, writes: "Uh, no. Call me a square, but if someone is going to ride a bicycle in downtown Chicago, or anywhere in this city, they absolutely should wear a helmet. (And knee, elbow and wrist pads, preferably.)"

Never having left North America in my life, it was also inconceivable to me that people would bike without a helmet, save for tooling around rural wherever on a cruiser at a few miles an hour. It's like seat belts: everyone does it, even if not actually everyone does it. But then I got interested in transportation policy, and it turns out America is something of an outlier, as John Greenfield writes:

Among the many topics we discussed was his attitude toward bike helmets. He [Mikael Colville-Andersen, who runs the consulting firm Copenhagenize] thinks they’re totally unnecessary for urban commuting, and he believes that promoting helmet use is actually counterproductive to making cycling safer. In northern European bicycle meccas like Copenhagen and Amsterdam, more than a third of all trips are made by bike, almost nobody wears a helmet, and yet injury rates are much lower than in the United States, where lots of people wear helmets.

This surprises Americans, like New York Times environmental writer Elisabeth Rosenthal: "Then I did something extraordinary, something I’ve not done in a quarter-century of regular bike riding in the United States: I rode off without a helmet." Now that American cities are rolling out bike-share programs, cities are loath to enforce helmet use because it kills the programs:

A two-year-old bike-sharing program in Melbourne, Australia — where helmet use in mandatory — has only about 150 rides a day, despite the fact that Melbourne is flat, with broad roads and a temperate climate. On the other hand, helmet-lax Dublin — cold, cobbled and hilly — has more than 5,000 daily rides in its young bike-sharing scheme. Mexico City recently repealed a mandatory helmet law to get a bike-sharing scheme off the ground.

The reasoning is this: it's better overall, and for overall health, to have more people biking, even if not enforcing helmet laws means that individual bikers are more at risk for specific injuries. Helmets work to prevent head injuries, no one doubts that, but the question is whether it's worth cracking a few skulls to make an omelet. This is why it's a paradox, Eric Jaffe writes, reflecting on a new study from the University of Toronto on helmet use in Canada:

[W]hat's clearly good for the individual rider appears oddly neutral (or worse) for riders at large. Public education and infrastructure upgrades, as the aforementioned works shows, protect riders considerably even before helmets come into play. Both efforts increase the overall amount of cycling, which provides safety in numbers. Mandatory helmet laws, meanwhile, may discourage riding to the point where public safety as a whole suffers from the relative decrease in physical exercise.

This suggests why cities don't want to enforce helmet laws. Having more cyclists makes the roads safer for cyclists; enforcing helmet laws means less cyclists; and the data suggests that it could be worse than a wash.

It's not an argument for not wearing a helmet. At the individual level the paradox goes away: it's safer to wear one.

And it's worth noting something Greenfield writes: almost nobody wears a helmet in "bicycle meccas like Copenhagen and Amsterdam," which have mature cycling infrastructure and greater awareness of cyclists from drivers and pedestrians (and other cyclists). If I ever make it to Copenhagen or Amsterdam or Paris, I might be willing to go helmetless. In Chicago, I'm not sure if I'm ready, or the city is.