Every sport has its own built-in factions: If you’re a runner do you wear minimal shoes or full-support ones? If you do yoga, do you like traditional yoga or hot yoga? When I started cycling I was pretty surprised to find that the point of division was whether or not your wore a helmet.
“Who doesn’t wear a helmet?” was my initial thought when I saw fellow cyclists pedaling without any protection on their heads. Hadn’t they seen the stats showing that helmet save lives? I’m squarely in the helmet-wearing camp, using science (and common sense) to back-up my position. Because of that, I continue to be surprised that people on the no-helmet side of the argument also use science to support their claims. But it shouldn’t be too unexpected: The interesting thing with numbers is that you can spin them to support just about anything you want. (For a good example, see this tongue-in-cheek article on why seat belts and child restraints are hazardous.)
But back to bicycling. Yesterday, via Facebook, I was directed to yet another anti-helmet argument, this one written by a student at Yale. He had all sorts of supporting documents, pie charts, etc., that claimed to show: A.) that cycling is less dangerous than walking down the street, among other things; and B.) that helmets may actually be harmful.
I read the piece. Then I checked his math. And he was spinning the statistics to make his case. Here’s the beginning, and cornerstone, of his argument:
“In 1978 a team of scientists undertook an epidemiological study of head injuries in the San Diego area. As part of that study they looked at the overall causes of head injury by transportation type.
Here’s what they found:
Over half of all head injuries occur in motor vehicles and more people were hospitalized after walking down the street than riding on a bicycle. Or consider another statistic: According to a 2006 French study, pedestrians are 1.4 times more likely to receive a traumatic brain injury than unhelmeted cyclists.”
Here’s the problem, and the reason I read the rest of the piece with skepticism: This only takes into account people who were hospitalized after an accident. His equation only works if every single person who walks, bikes, drives, etc., is taken the to hospital. Once you adjust for the total number of people engaged in each activity—including the ones who never have an accident—the argument falls apart and biking doesn’t appear nearly as safe. It’s true that a fewer cyclists suffer from head trauma than some other forms of transport. But that’s only because there are so many fewer cyclists than pedestrians or drivers. If you take into account the percentage of the population that bikes versus those who walk or drive it becomes apparent that cyclists are actually far more likely to suffer some sort of traumatic injury.
I know this because I looked around and found some stats of my own. They don’t completely jibe—the numbers are from different years, they only account for recreational activity, etc.,—but I just want to paint a broad picture. So here it goes:
According to the Pedestrian and Bicycle Information Center, which is funded by the U.S. Department of Transportation, in 2011 approximately 677 cyclists and 4,432 pedestrians were killed in crashes with motor vehicles. (Sorry for the grim numbers—I couldn’t find any related to just injuries.) That’s a lot of pedestrian deaths, but how many more people get around on foot than by bike? There are no actual stats that show how many people walk outside of their homes, which is basically all it takes to be a “pedestrian”. There are 313.9 million people in the U.S., and I would assume that a large number of them qualify as pedestrians. But I can win this argument even with a less liberal use of the facts.
The Sporting Goods Manufacturing Association keeps stats on the number of people who participate in various sport and recreational activities. Per their most recent report, from 2012, around 112,715,000 people walked for fitness that year. (Again, these numbers don’t account for all pedestrians.) The same data set says that 39,834,000 rode bicycles on paved surfaces at least a few times in 2012. So 1/3 fewer people biked than walked for fitness, and only 1/9 of the population even touched a bike in the last year. Of course, there’s no telling how many hours were spent on bikes versus on feet throughout the year, which should also be factored in if you want to make this a truly fair analysis. (I’m an avid cyclist, but I still spend more time walking than riding and I suspect I’m not alone.)
What does all of this mean? That the world is scary and dangerous and you should protect yourself as well as you can during the more dangerous things. To me, these stats paint a very clear picture that biking is one of the more dangerous modes of transport, but it’s worth the risk so I always wear a helmet. Not everyone reads these stats the same way, and that’s fine—it still confounds me that people can reach different conclusions while using the same science but these different interpretations sparked some interesting debate and helped me better understand (a little) why helmet-less riders feel supported in their position. The bottom line: However you bike—with a helmet or without one—be safe!
May 7th, 2014