From personal experience I can attest that it is almost impossible, in the US at least, to have an intelligent conversation about bicycle helmets. The universal view is that you have to be crazy not to wear a helmet. Since I almost never wear a helmet this is not a good way to begin a productive conversation.

I think the issue is far more complex than most people believe. It's a great example of unintended consequences, and that what seems obvious may not always be so.

Now let me be the first to admit that I am not against bike helmets. If you want to wear a helmet then you have every right to do so. I'm not going to argue with the proposition that if you fall on your head while cycling you are almost certainly better off if you are wearing a helmet. (But -- and this is not my main point, just a point worth noting -- it's been suggested that wearing a helmet creates a comfort level that leads some people to take more risks. So it's at least possible that for some people wearing a helmet may actually increase their risk.) Let me also acknowledge that you would have to be crazy not to wear a helmet in a bike race, or while mountain biking, or while taking part in any other sort of inherently dangerous type of cycling. My argument against helmets only concerns routine commuter or casual cycling.

Here's my main point: I am opposed to public health campaigns that focus on helmets, thereby implanting in people's minds the dangers of cycling. Instead, in my view, the public health agenda regarding cycling should be to promote the far greater health benefits of cycling. The overarching goal of any public health campaign should be to dramatically increase cycling in the US, thereby increasing physical activity and helping to reduce obesity and diabetes. In tiny Denmark, by way of example, one expert, Lars Bo Andersen, PhD, of Western Copenhagen University of Applied Sciences, reports that "26 persons were killed in the whole country in cycle accidents last year, but more than 6000 deaths were avoided due to the huge amount of physical activity this behavior is a result of."

As I wrote last week, despite the increase in accidents linked to cycling, the overall public health benefits of cycling are enormous. If the goal is to begin to increase cycling in the US to levels seen in the Netherlands and Denmark, where cycling is a routine part of everyday life, then people will need to think about cycling the way they think about walking or taking the train. Cycling needs to be completely routine. Imagine if you thought you had to put to put on a helmet before walking or driving. You'd probably do it less often. (For a variety of reasons I won't go into here I don't think the seat belt analogy is relevant here.)

It is true that, given the less advanced infrastructure in the US and the absence of a cycling culture, cycling is more dangerous in the US than in countries like the Netherlands and Denmark. However, the public health benefits of cycling will likely be even greater in the US. Cycling in the US will never achieve optimal levels of popularity if helmets are viewed as necessary. Therefore, everyone should be encouraged to cycle; campaigns to increase the use of helmets in casual cycling are therefore counterproductive on the large scale of public health.

Western Australia perfectly illustrates the issue. Following enforcement of a law mandating bicycle helmets, cycling became less popular. Paradoxically, the roads became more dangerous for cyclists and motorists alike. The law had the overall effect of damaging the public health, the law's critics contend.

I'm a baby boomer who grew up in the suburbs riding a bike. No one had a helmet in those days. Now I ride all over New York City on my hybrid bike and never wear a helmet. A major reason why I ride is to recapture a tiny bit of the feeling of joy and freedom that I experienced when I was younger. If I felt compelled to wear a helmet I suspect I would ride much less. In my opinion, despite the increased risk for a rare head injury, I am better off because of the decreased risk for all sorts of chronic diseases, not to mention the substantial and immediate increase in my overall happiness.

One argument in favor of helmets is that in Denmark, which rivals the Netherlands when it comes to cycling popularity, helmets are growing in popularity. But I don't think this is a reason for a public health emphasis on helmets in the US. A public health emphasis on helmets in a nation that's already achieved extremely high cycling levels may have a very different effect than a similar message in a nation with far lower levels of cycling. The first goal in the US should be to increase cycling. If this is successful and results in a big increase in head injuries then a helmet campaign might be warranted. For now, it seems to me, we should devote our messaging resources to getting people on bikes.

In response to arguments about helmets, Andersen makes an important distinction between promoting helmet use and legislation requiring its use. "I can support promotion but not legislation. The problem is you would get a fine every time you were caught without a helmet if you have legislation. In Denmark, the bike is used as daily transportation and sometimes it is not convenient to bring a helmet, because there is nowhere you can put it if you take your bike to the city. If you hang it on the bike it will be stolen and it is inconvenient to carry it around. This fact would decrease cycling substantially in Denmark if we got legislation. We know that 26 persons were killed in the whole country in cycle accidents last year, but more than 6000 deaths were avoided due to the huge amount of physical activity this behavior is a result of. Any reduction in cycling will cause more morbidity and mortality than all cycle accidents taken together. Therefore, helmet use should be promoted but not my legislation."