What is the best bike helmet?

Ontario is considering a mandatory helmet law, so I thought I’d write a post about bike helmets.

Most bike helmets are designed to protect your head in very specific conditions: when you fall off of your bike and land right on the top of your head. They are not particularly good at protecting you from twisting your head, getting hit on the side, nor, of course, hurting any other part of your body. They are not meant to protect you from getting hit by a car.

So, really, the first question is this: under what conditions should you wear a bike helmet?

To most people, the answer is obvious: whenever you’re riding a bike. Others say you should never wear a helmet when when biking. This is actually a very divisive issue for the cycling community. I’m going to give you my take on it. 

On one side is common sense, and sometimes the law. On the other side is science.

Guess which side I’m on?

Let’s look for the underlying logic of the pro-helmet faction. Why would you wear a helmet when riding a bike? Presumably the answer is because biking is dangerous to your head and it needs to be protected. Well, dangerous is a relative term, but let’s go with this. To be consistent, we would suggest that any activity (e.g., skateboarding, surfing) that is dangerous to your head should be done wearing a helmet. So if you believe that cycling is dangerous enough to warrant wearing a helmet, it follows is that engaging in any activity that is as dangerous as biking should be done wearing a helmet as well.  

Make sense?

What if I told you that driving was just as dangerous than biking? To be consistent with the above reasoning, you’d want to wear a helmet when driving. In fact, some companies have tried to market driving helmets.
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpHboUNuJv68IGld7q2oP3B6Anfa-a852RKDOOapsGESduDk4BoB1o6XDb13QQUxSkZEN2QM2J42l1RVMfqwkxe3QUYQUFI0FUGNnPq6gXHvJFa57_Hu5k5XcOaL3ex7mGrYY-VQ/s400/Motoring+Helmet+1.jpg
http://www.copenhagenize.com/2009/10/australian-helmet-science-for-motorists.html
Well, you’d feel pretty silly wearing a helmet while you drove your Ford Fiesta to the store, wouldn’t you? Why is this? It’s because helmet wearing is not a part of driving culture, and it is a part of biking culture. 

Well, it turns out that driving is as dangerous as biking. Not only is just as dangerous in the short term (the accidents are more likely and more lethal), but in the long term as well-- when you’re driving you’re not using some other form of transportation that involves exercise. And exercise is good for your health (Some studies show that cycling is safer. Other studies show that it’s just as safe. Others show that it’s more dangerous if you calculate it by the distance, rather than the trip or the hours spent. To play it safe I’m going to treat them as being equally dangerous.) See this web page for references (it’s a great read on its own):
http://webcache.googleusercontent.com/search?q=cache:http://www.kenkifer.com/bikepages/health/risks.htm

The cultural aspect of wearing a helmet is important to wrap your head around. If one tries to justify wearing a helmet because of cultural reasons, one is basically saying that it’s fashion. In this case, you have no business telling anyone else what to do, any more than you should go up to someone and tell them that they shouldn’t be wearing such and such a color because it’s not in this season.

It gets even sillier. Even walking is as dangerous as cycling (some studies show that it’s more dangerous.)  So perhaps we should continue to wear the helmet when we get out of the fiesta and walk to the store from our car. To be consistent, we’d wear helmets every time we left the house.

Cycling feels more dangerous than walking and driving. Why is this? It’s because we’re not used to it, and cycling accidents are so rare they make the news (if there is a particularly devastating car accident, it might make the news, but the newscasters will never mention that the drivers were not wearing helmets. Just seatbelts.) However, cultures are full of irrational fears, and the fear of cycling is one of them.

Cycling is actually really safe. Given all of the risks, and all of the health benefits of cycling, one study found that cycling’s benefits outweigh the risks twenty to one.
http://cyclehelmets.org/1015.html
This is incredible. If the benefits outweighed the risks just two to one, that would mean that cycling is twice as good as not cycling. But it’s twenty to one! Amazing. (Get a bicycle.)

You might be saying to yourself that wearing a helmet couldn’t hurt. That's common sense.

You’d be wrong.

How Wearing a Helmet Increases Your Chance of Head Injury

All of the studies cited in favor of helmet use involve findings that your head will be better protected in the case of an accident. When this ignores is the fact that helmets might affect your chances of getting into accidents at all. Part of this is because the helmet effectively increases the size of your head, making you more prone to banging it and twisting it (football helmets have the same problem). However, a larger problem is a fascinating effect called “risk compensation.”

Risk compensation is a psychological effect. Here is how it works: whenever you do anything, the risks you take depend on your perceived safety. For example, when you’re walking on a slick marble floor, you might walk more quickly in rubber-soled shoes than in dress shoes with leather soles. You drive faster when the streets are empty than when there are cars and people everywhere. On a bike it’s the same thing. Every decision you make on a bike--every time you turn left, ride off a curb, determine your speed, think you can make it before that car gets to you, decide you can squeeze between those people, etc., is affected by your perceived safety.

Risk compensation is a problem when the increased perceived safety exceeds the actual increased safety. It looks like bike helmets feel more safe than they actually are. Recall that helmets are made for protecting you from falling off of your bike. But most people wear helmets out of fear of car accidents. Basically, people ride more recklessly when wearing a helmet than when they are not.
http://www.vehicularcyclist.com/hfaq.html#A10

I’m sure you’re thinking “not me!” This is all subconscious. You might try to compensate for risk compensation. Maybe, if you are always concentrating on it, that will work. But likely you’re thinking of other things when you cycle. But in any case, you can’t control the behavior of cars.

Cars have a bit of risk compensation with respect to bike helmets too. In fact, one study found that wearing a bike helmet made cars drive frighteningly closer to you.
http://www.drianwalker.com/overtaking/
Given that cars are supposed to stay three feet from you when they pass, six inches closer is a lot. At some level, helmets make you look indestructible to cars, and, to some extent, to yourself.

[Note added in November, 2016: The study above was re-analyzed and concluded to be inaccurate in its conclusions: https://www.ncbi.nlm.nih.gov/pubmed/24086528 ]

The effect of risk compensation on biking is increased head injuries. That’s right, as nuts as it might sound, wearing a helmet increases the chance of getting a head injury.  The rate of head injuries per active cyclist has increased 51 percent just as bicycle helmets have become widespread.

http://cyclehelmets.org/1028.html
This is true even though the helmet offers protection should you get into an accident-- it’s just that the increase in the chance of getting into one outweighs the protection the helmet offers. If the helmet offered more protection, this might not be the case. But as long as bike helmets are little more than bowl-shaped coffee cups, I suspect the situation won’t change.

Do I think people should wear bike helmets? In general, no. However, risk compensation can be used to your advantage.

When It’s a Good Idea to Wear a Helmet

When I was in high school, I tried to do some skateboarding. This is a sport that requires incredible bravery. I never got good at it, and a part of that was because I was chicken. In a situation like this, where one might want to take more risks, and push oneself further, the helmet might help. If I were a BMX stunt biker, a bike racer, or a downhill mountain biker, I would probably wear one, precisely because it makes you take more risks, and if you're chicken like me, that's the only way to get good.

But if you’re cycling for exercise, fun, or transportation, I don’t recommend it. 
And I wholeheartedly recommend cycling for exercise, fun, and transportation.

I believe that wearing a helmet is bad for another reason that is based on a theory I’ve been developing about the human mind. Before I describe it to you, I should make clear that this theory is still being formed, and has no direct evidence for it yet.

The theory goes like this: when you want to be a certain way, you will do a few things until you feel satisfied that you are being that way. For example, if you want to be good to the environment, there will be some point at which you are doing enough things for the environment (e.g., cycling, recycling, taking shorter showers) so that you are satisfied with yourself. After that point, you feel no need to do anything further.

The consequence of this is that everything you’re doing for the environment takes up a valuable slot. So if one of the things you’re doing for the environment actually does very little good for the environment, there is an opportunity cost: because you’re doing X you’re not doing Y.

I think this is happening with safety. When you wear a helmet, you feel a bit safer, and this is drawing mental resources from other ways to be safer, such as obeying traffic laws. I should mention here that most bike accidents are the fault of the cyclist. Obeying traffic laws is the single best thing you can do to be safe on a bike. But when I mention that I bike, people don’t ask me if I’m obeying traffic laws. They ask me if I wear a helmet.

"Over the past several decades, society has come to equate safety with helmets," said Charles Komanoff, the co-founder of Right of Way, an organization that promotes the rights of cyclists and pedestrians. "But wearing a helmet does not prevent crashes." (from a New York Times Article  http://cyclehelmets.org/1028.html#1)


Why Helmet Laws Should Not Exist (I'm talking to you, Ottawa)

If bike helmets increase your chance of getting hurt, it seems obvious that helmet laws are a bad idea. Indeed they are. All 50 states in America have some kind of helmet law, and I believe that all of those laws are increasing head injury for the reasons listed above.

However, helmet laws are bad for another important reason: it decreases the amount of cycling that happens.

Cycling is very good for you. Some people will simply not cycle if they have to wear a helmet. Perhaps they don’t like how they look. In this article, 14% of people cited helmets messing up their hair as a reason they don’t bike:
http://www.goinggoingbike.com/blog/appearance-a-factor-in-stopping-the-irish-cycling-to-work/
Perhaps they don’t know what to do with the helmet when they lock their bike. Perhaps they don’t want to mess up their hair. Perhaps they don’t want to look like a dork. Perhaps they want to impress me. Perhaps they don’t feel like putting it on. They are inconvenient, expensive, and constitute a threshold that some people won’t want to cross. According to this TED talk by Mikael Colville-Andersen, car companies know that if there were a car helmet law, people would buy fewer cars, and car companies are in favor of bike helmet laws, because the lack of such laws would increase cycling, and reduce car sales.
http://video.tedxcopenhagen.dk/video/911034/mikael-colville-andersen

So reducing cycling is bad because it means the population is getting less exercise. And as I mentioned above, all things considered, cycling is great for you.

Another reason it’s bad is because the more people are cycling, the safer all cyclists are. Why? Because when there are a lot of bicycles on the road, car drivers are used to them, expect them, and take more care not to hit them. This is one of the reasons that when a bike helmet law comes into effect, cycling goes down and head injury goes up. It’s shameful.

Some of you might be thinking that, okay, maybe we can let adults ride without helmets-- they have more motor control, but kids should have to wear helmets, right? Many laws (including in the city I live in, Ottawa) require children to wear them. But it turns out that the risk compensation I mentioned above is stronger for kids than it is for adults! This is also coupled with the fact that kids have a lower center of gravity, and, as a result, falls hurt them less. When I see a parent riding without a helmet with their kid with a helmet, it takes all I have not to say something. But maybe they’re just afraid of getting a ticket. A few kids even get strangled by the helmets (http://cyclehelmets.org/1227.html)!

Finally, it’s a bad idea because it contributes to our cultural fear of cycling, which is, first of all, irrational (you would have to bike an expected 3000 years to get into a fatal head injury), and second of all, for the reason in the last paragraph, kind of self-fulfilling. I won’t link to websites that promote the idea that cycling is dangerous-- I don’t want google to credit the sites because of my linking to them. Cycling is so safe that if anybody, or any website, mentions danger when cycling comes up is being irresponsible.

Helmets: The Last Two Centimeters of Safety

If you were involved in an accident, or know someone who was involved in an accident, you might think that this is a good reason to wear a helmet. I would urge you to pay attention to studies, not your own personal experience. If you think a helmet saved your life, check out this link:
http://cyclehelmets.org/1209.html

I’ve talked to nurses who think they know something about helmets because they see cyclists in the ER with and without helmets. But keep in mind that the medical profession sees a biased sample-- they see only those who got into accidents, and only those accidents serious enough to warrant a hospital visit. They also don’t know who many of the head injuries they see would never have happened if the cyclist had not been wearing a helmet.  Ottawa’s coroner is in the same position, with respect to his or her personal experience. This is another example of how you should not use personal experience as a substitute for scientific studies. Scientific studies are rarely biased; your personal experience always is.

Still want a coffee cup on your head? 

If you insist on wearing a helmet, please wear it correctly. See this link.
http://www.howtoadvice.com/WearHelmets
When I see people wearing helmets way up on their forehead, or unstrapped, it’s very sad, because they are increasing their risk of an accident and at the same time not getting the minimal protection the helmet provides.

When I see people wearing helmets in the grocery store, it's very sad, because they look like idiots. But then again, they are probably at more risk to their head in a grocery store (you could slip on milk!) than on the road, so maybe they're being consistent.
Scientific Evidence
I have written this essay with relatively few references. This is because there are many, many studies out there, and each requires a careful eye to interpret correctly. I could cherry pick papers that support my points, but people who disagree with me could do the same. What I have written here is my impression based on the reading I’ve done on the subject over the course of the last five or six years. If you wish to read more,
http://cyclehelmets.org/
has a pretty exhaustive account of the research out there.
This link is also good, in the form of an essay:
http://webcache.googleusercontent.com/search?q=cache:http://www.kenkifer.com/bikepages/health/risks.htm

Conclusion

So what’s the best bike helmet?

It doesn’t really matter so much which bike helmet you get. The important thing is not wearing it.

References

Mok D, Gore G, Hagel B, Mok E, Magdalinos H, Pless IB, 2004. Risk compensation in children's activities: A pilot study. Paediatr Child Health 2004;9(5):327-330. (Children ride with more risk and suffer more crashes when wearing a helmet)

adults are more likely to ride on busier roads if helmeted (Gregory, Inwood and Sexton, 2003).
Gregory K, Inwood C, Sexton B, 2003. Cycle helmet wearing in 2002. Transport Research Laboratory Report 578.