Noah Brier | September 6, 2019

Why is this interesting? - The Helmet Edition

On bikes, safety in numbers, and the helmet debate

Noah here. Bike helmets are back in the news this week with the New York Post reporting that Bill de Blasio is considering requiring them for Citi Bikers. This comes on the heels of the 21st cyclist death in NYC this year, an astronomical and frightening number for anyone that likes to get around on two wheels (and more than twice the count from last year). The problem, as any pro-bike organization will tell you, is that requiring bike helmets can actually make cycling far less safe by keeping people off the streets. As a 2004 paper from the medical journal BMJ concluded, “A motorist is less likely to collide with a person walking and bicycling if more people walk or bicycle. Policies that increase the numbers of people walking and bicycling appear to be an effective route to improving the safety of people walking and bicycling.” The city’s own Department of Transportation agreed in a 2017 report, explaining that “The growing number of cyclists on our streets is a likely contributor to the positive changes in cycling safety.”

Everyone seems to agree that the most important thing you can do for cycling safety is to encourage people to ride. If you want to make the streets safer for those cyclists there are also a number of infrastructural changes that have been proven effective, most important of which is adding more protected bike lanes

But this isn’t actually what I want to talk about today. The Post article also mentions something I’ve seen (and heard) referenced a few times over the last few months: That there’s some debate over the merits of bike helmets. The argument includes a few core components. One is that bike helmets, when made compulsory, bring down ridership. That seems widely agreed upon. But the other two arguments are that many helmets are flimsy and that riders who wear helmets “are likely to take more risks on the road than if they just wore a baseball cap”. (The latter argument comes from a 2016 paper.) It’s these I want to dig on.

Why is this interesting?

When I first heard some version of this helmet argument I was having drinks with a friend a few months ago. He said he had heard that helmets can do more damage than good because they can constrict the movement of your head or something like that. He swore he had read about it and I quickly started Googling to find an answer. I started by seeing if Cochrane (WITI 6/27) had done any meta-studies on helmet usage and alas, they had. Here’s what they found in 1999:

We found no randomized controlled trials, but five well conducted case-control studies met our inclusion criteria. Helmets provide a 63 to 88% reduction in the risk of head, brain and severe brain injury for all ages of bicyclists. Helmets provide equal levels of protection for crashes involving motor vehicles (69%) and crashes from all other causes (68%). Injuries to the upper and mid facial areas are reduced 65%.

Unfortunately that study wasn’t without controversy, so I kept looking around. What I found was two more recent systematic reviews that both came to the same conclusions: Bike helmets are undoubtedly effective at protecting your head in a crash. “Bicycle helmet use was associated with reduced odds of head injury, serious head injury, facial injury and fatal head injury. The reduction was greater for serious or fatal head injury,” explained a 2016 meta-analysis published in the International Journal of Epidemiology. A 2018 study in Accident Analysis & Prevention found that “Bicycle helmets reduce head injury by 48% and serious head injury by 60%.” Not quite the numbers from the Cochrane analysis, but still worth it if you care about a not broken head.

While that answers the question about flimsy helmets (something is better than nothing), it doesn’t answer whether you’re more likely to get in a crash while you’re wearing a helmet. There does seem to be some evidence that people are willing to take more risks when wearing one and that drivers may pass more closely when they see a rider with one on their head. In the end it’s a set of personal safety questions (will a helmet protect you in a crash? probably, will it change the way you ride? maybe) combined with a more complicated set of social questions (will a helmet change the way other cars treat you? potentially, would mandating them cut down the number of riders and make you less safe? almost definitely). The conclusion to the 2019 paper on drivers passing more closely does a nice job tying these together:

Even if bicycle helmets offered 100% protection from the impacts of motor vehicles, this is, critically, a risk imposed upon bicyclists without their consent. To paraphrase Voeckler (2007), suggesting that bicyclists must buy and wear protective devices to remain safe is no different from suggesting non-smokers must buy and wear gas-masks as a solution to passive smoking. In both cases, these are solutions that technically ‘work’, but they place all the responsibility for action – and a financial burden – on the non-consenting injured party. In the case of bicycle helmets, it is, moreover, a ‘solution’ that serves to maintain a status quo in which people choosing a healthy, clean and socially responsible mode of travel are systematically marginalised (Aldred, 2014) in their competition for limited public space with those who have chosen to use motor vehicles. 

So should you wear a helmet? Probably. Should you be required to wear a helmet? No. Should we do more to protect cyclists from cars? Definitely.

Helmet of the Day:

I got one of these Morpher helmets a few months ago and I love it. I just leave it in my backpack and strap it on whenever I hop on a bike. (NRB)

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Thanks for reading,

Noah (NRB) & Colin (CJN)

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