Four Myths About Helmets and Safety

Josh King in his commuter armor
Josh King lives in Seattle, where he commutes by bike every day, rain or shine. Earlier this year he switched to full-time single speed commuting; you can read his thoughts on going gearless at

If I was surprised about one reaction to my "10 Rules" post, it was the number of comments taking issue with my advice to wear a helmet when commuting in the city. Although all of the rules seemed commonsensical (to me), I thought that one in particular was non-controversial. Turns out I was wrong. But instead of paeans to free choice, much of the anti-helmet clamoring seems to try to justify not wearing a helmet as a safer (or safety-neutral) choice. Let's look at the primary anti-helmet rationalizations:

  1. "There's No Scientific Data Indicating Helmets Reduce Risk of Injury."This is your brain on myths (via TreeHugger) Actually, there is. But the data is fairly thin, and anti-helmet forces have seized on this, arguing that the paucity of scientific evidence indicates that helmets must not really do any good. But this argument suffers from the negative proof fallacy–the implication that because the efficacy of helmets has not been conclusively proven via scientific studies, helmets must be valueless. But consider how many propositions we accept as true in the absence of any scientific studies proving them so. For example, I don't know of any studies proving that ritualistically slamming my head into the door jamb on the way out every morning leads to a greater incidence of brain injury. But I needn't make such demands on empiricism. I know it's bad a idea, and I don't need a study to tell me that. It's hardly less intuitive that wrapping one's melon in a layer of foam padding will help reduce the severity of cycling head injuries. Why–particularly given the obvious difficulties of getting enough scientifically and statistically credible data to prove or disprove the real world benefit of helmets–should we demand absolute scientific proof before admitting that wearing a helmet is a risk-minimizing choice?
    Still not convinced? Try a simple thought experiment: You've just been doored. As you fly over the handlebars, would you rather be wearing a helmet or not?
  2. "A Helmet May Make Injuries Worse." Some have pointed out the possibility that helmets have the potential to increase the severity of certain "rotational" injuries–those where the head is jiggled about rather than suffering a direct impact. One glaring problem with this argument is that fact that the anti-helmet lobby runs with it–despite it being based on nothing more than conjecture–while demanding scientific levels of proof of helmet efficacy. But as pointed out above, we know that putting a layer of foam between our heads and an impact will mitigate the harm in most impacts. In effect, the "rotational ijury" argument is the logical twin of the anti-seatbelt argument that one could be stuck seatbelted in a submerged car. Yes, there is an edge case where the helmet could hurt. But are you going to plan for the edge case or the likely case?
  3. "Data Shows That Requiring Helmets Is a Net Negative for Society." Well, not a lot of data–certainly not a lot more than the helmet safety findings anti-helmet folks scoff at. But there are some fairly compelling findings, particularly from Australia and New Zealand. And it's at least somewhat intuitive that mandatory helmet laws would act as an impediment to bike use (particularly for newcomers to cycling) and a distraction from infrastructure investments aimed at making cycling safer. But we're not talking about society. We're not talking about whether helmet use should be mandatory. We're talking about YOU– you who have already decided to commute to work, and are trying to figure out if wearing a helmet is going to make you safer. At that point, all of the "net effects" data is completely meaningless.
  4. "Helmet Use Leads to an Increase in Risk Taking." Phrenology HelmetLike everything else in the world of scientific study of helmet use, the data is very thin. But there is some evidence that indicates a potential correlation between wearing protective gear and riskier behavior (and there is some evidence to the contrary). Would wearing a helmet cause a rider to pass closer, ride faster, etc., thus negating the safety benefits of the helmet? This doesn't feel intuitively right to me; I've had enough road rash and bruises that it would take full body protective gear to materially change the risk profile of my riding. However, this may not be the case for everyone. Ask yourself–would wearing a helmet change how you ride? Would it change it enough to overcome the safety benefits?

Ultimately, it comes down to being an adult and exercising adult judgment. Mandatory helmet laws (such as we have in Seattle) are a bad idea, for reasons too numerous to mention here, but we can't let animosity toward the law impact our judgment. If you're not wearing a helmet, you're missing something that helps reduce your risk of injury. Now, you may well decide that this risk is vanishingly small, because you're riding on a lakeside bike path, or suburban trail, or in Copenhagen. Or you may decide that you're the type of person who needs to not wear a helmet in order to keep your riskier riding habits in check. But whatever you do, your decision whether or not to wear a helmet should be driven by objectively weighing the issues, not by rationalization or blindly following one of these myths.

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