Some notes on helmets and bicycling and public health

Andy Thornley

Again, it is as if the protection of offender and victim is deserving of like consideration. This is unjustified: even on the questionable assumption that in collisions between a car and a pedestrian, both driver and pedestrian are equally to blame, vehicle drivers are far more often associated with the serious injury or death of pedestrians and cyclists than the reverse. Indeed, 97% of pedestrians and cyclists are killed or seriously injured as a result of a collision with a motor vehicle — mainly cars. From this perspective, far from it being not safe to walk or cycle, it is clearly highly dangerous to drive.

— Meyer Hillman, Destroying Travel Myths: "It's not safe to walk and cycle", Policy Studies Institute, June 20, 2000

Supervisor Bevan Dufty, whose district includes the intersection, said that at dusk on the same night, he witnessed another bicycle-car collision at Eddy and Fillmore streets.

A taxicab made an illegal U-turn at the intersection and hit a bicyclist who wasn't wearing a helmet, Dufty said. The bicyclist survived the collision and the cabdriver waited at the scene.

— Bicyclist clings to life after collision, San Francisco Examiner, March 11, 2008

I get into a lot of conversations with people about helmets and bicycling and safety and public health, by virtue of my position on the staff of the San Francisco Bicycle Coalition and my constant coming and going by bicycle in San Francisco. People are surprised, often almost offended, that I don't wear a helmet when I ride my bike — everyone knows how dangerous it is to ride a bike, and I'm not only imperiling myself but setting a bad example to other cyclists when I ride bareheaded.

Here's my own personal position: I choose not to wear a helmet while bicycling in San Francisco because I'm very mindful of how I look and don't want to give anyone the wrong impression about how safe it is to ride a bicycle in San Francisco. I'm too busy working to facilitate and encourage urban bicycling and the many benefits it brings to spend any of my limited time and energy constructing fear.

Three key points:

riding a bicycle in San Francisco (predictably, respectfully) is a lot safer than you think
a bike helmet, even properly fitted, doesn't protect you as much as you think
25 bareheaded bicyclists riding on a given street is a significantly healthier situation in the aggregate than 3 helmeted bicyclists riding on that same street (and the particular safety of an individual cyclist is likely to be higher in the big bareheaded group)

I want to be clear that the SFBC doesn't actively discourage helmet wearing for bicyclists — our official advice is that, all things considered, you're better off with a helmet than without (and of twelve full-time staff at the SFBC, I'm one of a handful who practice this renegade bare-headed policy). Basically, if wearing a helmet will help you feel comfortable bicycling in the city, please wear one (properly fitted); if wearing a helmet discourages you from bicycling in the city, then don't feel obliged (but for everyone's sake ride predictably and visibly and follow the rules of the road).

And if you bomb your bike down Repack Road or Conzelman Drive, or engage in risky riding behaviors like running red lights without looking or running alleycats with Lucas Brunelle, you probably should be wearing a helmet (of course, that's where Lucas mounts his camera). And I suppose people given to clumsiness or balance issues should think about armoring up the tops of their heads as well (whether cycling or walking).

For further reading check out this post by Alan Durning from Grist's blog that's got lots of great stuff to chew on. Durning asserts that bicycling is safer than most people think, pretty much the same level of safety overall as driving (depending on whose numbers you're using). Indeed, because cycling is mistakenly characterized as "dangerous", the cycling population in the U.S. probably includes an above-average number of risk-takers who bring risky bike behavior onto the streets and skew the stats (and further injure perceptions by presenting the general public with examples of crazy daredevil biker behavior and discourage more timid "responsible" people from riding).

English public health researcher and thinker Meyer Hillman blew minds in 1992 when he published Cycle Helmets: the Case For and Against, which drew some provocative conclusions, chiefly that for the small benefit to individual cyclists in wearing a helmet a significantly larger detriment of compound fear and discouragement is cultivated:

. . . people are discouraged from cycling if their perception is heightened that it is a 'dangerous' form of travel and that it is only safe to do so if a helmet is worn. The result of this is that the considerable latent demand for cycling – an ideal mode for the majority of the population for most of their journeys – continues to be suppressed. As cycling is also a convenient and routine way of maintaining fitness, a significant route to public health is prejudiced . . .

To the extent that multiplying bicyclists on the street is a very effective policy intervention for bicyclist safety and public health — more bike traffic = safer bicycle traffic (and generally safer pedestrian traffic and school kid traffic, etc.) — scaring people away from urban bicycling is unhelpful as a safety-building strategy. Sometime when you've got time and you're feeling particularly wonky, bend your mind around Dave Horton's essay on "Fear of Cycling", which really chews over the whole issue of objective safety vs. perceived safety and the "construction of fear" (orange-level terror alert, anyone?).

Of course, bicycling could be safer, and there are lots of ways to address that, and we are and will continue to. But here's the big idea that we should be pushing: Not bicycling is statistically more dangerous than bicycling, in aggregate health terms — not pedalling can kill you!

I love Michael Bluejay's How to Not Get Hit by Cars, be sure to jump to the page on What's Wrong with Bike Helmets. Mr. Bluejay doesn't argue the case on libertarian or messy-hair bases, but on larger safety and public health grounds. Obsessing on bike helmets as the entirety of bicycle safety practice means that more fundamental safe-cycling habits are omitted from public discourse, as if we limited our drivers' ed cirriculum to "buckle up your seatbelt" and skipped the rest of the safe-driving instruction. Celebrated bicycle educator John Ciccarelli, a habitual helmet-wearer while cycling, says that bike helmet use is important but perhaps the fourth layer of safe cycling practice, well down on the list of must-dos. Ride predictably, ride visibly, ride respectfully, then consider wearing a helmet.

Count on Wikipedia for a long, nerdy exposition on bike helmets, rich with excellent references.

In 2001 the Consumer Product Safety Commission released research that showed that the number of cyclist head injuries had increased 10 percent since 1991, even as bicycle helmet use had risen sharply. But with ridership declining over the same period, the rate of head injuries per active cyclist had actually jumped 51 percent just as bicycle helmet use had become widespread. Read this NY Times story about the CPSC study for more on the unintended complications and compensations related to bike helmet use.

You may also have heard about Dr. Ian Walker's research into motorist behavior and bike helmets — with precise measuring gear, alternating helmeted and bare-headed rides of the same roadway, he found that vehicles tend to pass helmeted bicyclists more closely than bare-headed (and seem to give women a wider berth as well) — 23% more vehicles came within 1 meter of the bicycle when a helmet was being worn. Dig this Scientific American article about the research.

Here's a passionate essay on bike helmets from one of the great San Francisco moderns, Chris Carlsson. Again, the basis of his argument isn't that he doesn't want to look dumb or be burdened with an uncomfortable helmet, but that focusing exclusively (but ineffectively) on cyclists' survival in an inevitable catastrophic crash in a landscape where they don't belong, rather than re-shaping the streets for humane mobility (and de-privileging motor vehicles in the public realm), blames the victim and actually suppresses the larger public health benefits that increased routine cycling would bring.

Apiece with that "design for doom" theme (and a variant of the "license for carelessness" dimension of what Dr. Walker saw in his research) is the influence of improved car-crash technology (protecting car occupants) on driver behavior and the phenomenon of "risk compensation". Recent studies show that in spite of technical improvements, statistics for auto-occupant crash injuries and fatalities have stopped going down, after years of decline the curve has flattened — if it weren't for ever-better airbags and passive-restraint devices and car bodies that crumple and protect their occupants, the safety trend would be getting even worse. It seems likely that Americans are probably driving more carelessly than ever, in part because the "survivability tech" (for cars, at least) keeps improving — who needs to drive carefully if your SUV's massive frame and state-of-the-art airbags will save you if you wipe out (or you take out a busload of orphans, who cares)? Instead of heightening motorists' sense of responsibility for their actions, more-survivable cars (and forgiving high-speed freeway streetscapes) let motorists check out from engagement even further.

I'm not interested in capitulating to public policy failures and conducting myself as if selfish careless violence was inevitable. I'm interested in helping you visualize what civilization looks like, and shaping our city to realize that vision, and I encourage you to join those of us working to establish a civilized society right here in our own neighborhoods.

Ride your bike as if you weren't wearing a helmet and you'll live a lot longer, even if you are wearing a helmet. And we'll bring out more and more "normal" people to try biking, and the streets will be filled with people riding bikes as if it was a totally routine, civilized thing to do, and of course it will be.

To recap: If wearing a helmet will help you feel comfortable bicycling in the city, please wear one (but make sure it's properly fitted); if wearing a helmet discourages you from bicycling in the city, than don't feel obliged (but be sure to ride predictably and visibly and follow the rules of the road).

[here are a few recent pieces that lay it out better than I do:]

Howie Chong's Why it makes sense to bike without a helmet

Joseph Stromberg's Stop forcing people to wear bike helmets

Bicycle helmets and the law, British Medical Journal editorial by Ben Goldacre, Wellcome research fellow in epidemiology at the London School of Hygiene and Tropical Medicine (and the author of Bad Science and Bad Pharma), and David Spiegelhalter, Winton Professor of the Public Understanding of Risk at the University of Cambridge

[also see Some notes on mandatory bike helmet laws]

[also see Always wear a bike helmet]

[I used to like C.I.C.L.E.'s page on the matter of helmets and biking, but they've fouled it up — you can catch it cached on Google]

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