Are bike helmets really a no-brainer for cyclists?
When I was a high school senior, I ended up in hospital after the front wheel of my bicycle fell off when I caught some air on a kerb. I was not wearing a helmet. Mandatory helmet laws might seem like a no-brainer. Yet when the medical journal BMJ polled its readers in 2011, 68 per cent of the respondents opposed mandatory helmet laws. Proponents of helmet laws say they reduce injuries. But evidence for this claim remains mixed. Two studies published last month came to opposing conclusions. The first, published in BMJ, compared rates of cyclingrelated head injuries in six Canadian provinces before and after they passed helmet legislation. Researchers analysed data from 1994 to 2008 and, after accounting for baseline trends, concluded that ‘‘the overall rates of head injuries were not appreciably altered by helmet legislation’’. The second study, published in the Journal of Pediatrics, analysed statistics on United States bicyclists who were severely injured or killed between January 1999 and December 2009. The authors compared the injury and death rates among cyclists aged 16 and younger in states with mandatory helmet laws for youngsters to rates in states without such laws. They found injury rates were about 20 per cent lower in states with helmet laws. How could the two studies come to opposing conclusions? Because it’s inherently difficult to measure whether differences in injury rates are due to helmet legislation or other factors, says Jessica Dennis, an epidemiologist at the University of Toronto and lead author of the BMJ study. Helmets don’t prevent the things that cause a crash, but they do offer a last line of defence when things go wrong. Even most opponents of mandatory helmet laws advocate helmet use, but they say that the negative consequences of helmet laws outweigh the benefits. One of the first things that mandatory helmet laws do is decrease ridership, says Washington Area Bicyclist Association board member Jim Titus. Opponents also worry that mandatory helmet laws send a false message – that cycling is an inherently dangerous activity – when, in fact, it’s an activity with well-known health benefits. Meanwhile, it seems that bicyclists wearing helmets may encourage riskier driving by motorists. Traffic psychologist Ian Walker from the University of Bath equipped a bike with a sensor to record the distance between him and passing vehicles. He took more than 2300 measurements and found that motorists passed him more closely when he wore a helmet. The ability of bike helmets to reduce injury has been overstated, Titus says. Helmets are sometimes said to reduce the risk of head injury by 85 per cent, but that statistic comes from a 1989 study that has not been replicated. ‘‘Studies in the last 20 years have calculated that helmets prevent 10 to 40 percent of head injuries,’’ says Titus. His arguments apparently convinced the US Centers for Disease Control and Prevention and the National Highway Traffic Safety Administration. Last month, both agencies removed the 85 percent claim from the information they disseminate to the public. ‘‘We should be talking about other strategies to reduce cycling injuries’ beyond helmets,’’ Dennis says. Her study did show that injury rates dropped after helmet laws were implemented, but the effect disappeared when she took into account the rate at which injury rates had been falling before the laws took effect. This suggests that reductions were probably due to other measures, such as traffic calming, designated bike lanes and safety campaigns. These days, I almost always wear a helmet when I ride, but I recognise that it’s my last line of defence. Not long after my crash, a friend of mine experienced a nearly identical wreck. He was wearing a helmet, yet his injuries were similar to mine. Our wheels flew off because the quickrelease mechanism for the front wheel had come undone. A few years after my wreck, bike manufacturers began employing a safety apparatus to prevent this.A helmet may have lessened my impact, but to prevent the crash in the first place, I needed a safety strategy that looked beyond the helmet.
Bicycle maintenance: You’re never too young to learn how your bike works.