The Helmet Debate

So what do you need to get started riding in the city? A bike! Is that all? Well, it depends on who you ask. Bike helmets, and whether or not they should be worn by every cyclist, have been debated long and hard on cycling message boards and on city sidewalks. In most jurisdictions, it's ultimately the choice of the individual cyclist, though many US states have laws legislating helmet use for youth, and some cities and counties have laws about adult helmet use as well. Lots of people, cyclists and non-cyclists alike, have very strong opinions on the matter.

The helmet debate is less a debate about helmets (which are generally acknowledged to protect against head injuries to some extent) than it is a debate about helmet laws--and, to a lesser extent, whether or not you should be a jerk to cyclists who aren't wearing them (some folks even imply that those who choose to go helmetless don't deserve prompt and adequate medical treatment for injuries they might sustain while cycling).

The most basic of arguments in favor of helmets is easy to make: they protect against head injuries and, thus, against fatalities.

I looked at the actual standards to which cycling helmets sold in the United States are held (you can too) and ascertained that, basically, helmets are dropped, with a headform fitted with sensing equipment, onto a hard surface (an anvil that can be various shapes) from a height of about two meters. If the sensing equipment registers force above a certain acceptable threshold, the helmet fails and is not certified. In other words, helmets are certified to reduce the force to your head to acceptable levels if you fall or are knocked off your bike and your head hits the ground.

For those of you whose physics skills, like mine, are rusty, the speed at which you're traveling doesn't have all that much to do with the force at which you hit the ground, since the only thing that affects that force is gravity. If you've got a lot of momentum, you might slide once you hit, for sure, and if your slide is interrupted by an object, you might be in trouble, but your head's initial impact with the ground will be much the same whether you fall over at a standstill or while barreling down a mountain road at 30mph. It is that impact your helmet is designed to protect against.

Which means it won't protect against other kinds of crashes--or at least, not as well, say those who think the blind advocacy of helmet usage is, at best, problematic. If a car hits your head at 30mph, or even 20mph, or if your head hits the ground, slides, and hits something else, you're going to have serious problems whether or not you're wearing a helmet. I can't find any studies on types of impacts that usually occur in car-bike collisions, though, and if a car hits your bike or your shoulder before it hits your head, a lot of the force might have already been absorbed and your helmet might make a difference after all (to your head, anyway--your bike and your bones might be toast, but they're more easily repairable). I admit I'm just going on gut feeling here, though.

Anyway, various studies collectively suggest that anywhere between 40-88% percent of cyclists' brain injuries can be prevented by the use of a helmet, and anywhere between 1-90% of fatalities (sources: here, here, and here). The numbers are so wide-ranging that it's hard to identify any study as conclusive. There are many factors that complicate the issue, including changes in helmet design and efficacy over the years, and demographic and social questions--like, do people wearing helmets ride differently than people not wearing helmets? How about in Denmark? But all the studies seem to agree that helmets do offer protection.

So why would a cyclist choose not to wear one? For the same reasons that drivers and pedestrians don't wear helmets. They're inconvenient and sometimes uncomfortable, they interfere with hats and hairdos, and the perpetuate the idea of cycling as a dangerous activity requiring specialized equipment. Helmets also, some say, put the burden of collision-mitigation on cyclists rather than on the people who are causing most of the collisions: drivers (one source for this claim is here). Instead of passing helmet laws, jurisdictions should be creating infrastructure to make cycling safer and passing laws that call for harsher penalties for drivers who hit cyclists.

Others argue that wearing a helmet may in fact be less safe than going bare-headed. They bring up the topic of rotational brain injury, which is caused by the brain rotating within the skull. Some suggest that not only do helmets not prevent this type of brain injury (since it's not exactly caused by blunt force), they may in fact exacerbate it or make it more likely by increasing the diameter of the head. The result is diffuse axonal injury, which can cause coma and persistant vegetative state, or death. (See summaries of this argument here and here.)

These folks also bring up one British traffic psychologist's study suggesting that drivers pass much closer to cyclists wearing helmets than those who are not. If safety should be first and foremost about preventing collisions (and it should), and there is some evidence that wearing a helmet makes collisions more likely, should you go bare-headed for safety?

Of course, this relies on the driver actually seeing you (in order to give you more space if you're not wearing a helmet), and how many of us have heard drivers cry, "I didn't see you!" after a close call or a collision? If a driver doesn't see you, whether or not you're wearing a helmet will have absolutely no impact on whether or not the driver hits you. Besides, the study is not without its problems-- the author's sample size is one, and there's no way of knowing if he was riding differently when he was wearing his helmet.

Another common refrain, from the pro-helmet contingent, is "my helmet saved my life" (or my sister's life, my kid's life, my cousin's wife's uncle's life). Anecdotal evidence for helmets' efficacy abounds. But those who are unfriendly to helmet legislation or promotion are quick to point out that such stories are merely anecdotal. There's no evidence that the impacts that helmet defenders describe would have resulted in head injury if the rider hadn't been wearing a helmet. Indeed, perhaps the only reason the helmet hit the ground (or the car, or whatever), thus fueling the rider's "my helmet saved my life" feeling, is that the helmet itself increased the head's weight and size, however slightly, making the impact more likely. Helmet promoters might respond to this suggestion by asking for any evidence, anecdotal or not, of a death that has occurred because a rider was wearing a helmet. I haven't (yet) found any such evidence or documentation in my online research on the issue.

Obviously, helmets do not prevent injuries to other parts of the body, which can certainly be life-threatening and life-changing. However, some statistics suggest that head injuries account for over 60% of bicycle-related fatalities (source). Even if helmets can only prevent some of those head injuries, those are pretty convincing numbers. Almost everyone seems to agree that helmets are a good idea for children and those new to biking, who are more likely to experience low-speed falls resulting in injuries that helmets are really designed to protect against. And even experienced, careful cyclists crash every 4,500 miles on average--at least, that's what Google tells me, though I can't find a definitive source for that number. Based on my experience as a careful cyclist, I'd say it sounds about right, if I include leafpile wipe-outs and minor falls.

By far my worst crash so far came from getting hit by a car. The driver of a pick-up truck failed to yield while turning left across an intersection I was going straight through. My collarbone was broken and my knee injured; it was a miserable experience. I must admit that, in addition to my other injuries, I have my own "my helmet saved my life" story of the experience--when I got my broken bone pain under control, I discovered a bruise on my head, underneath where my helmet had been. I concluded that my helmet had absorbed some of the impact. Really, I don't know exactly what happened--I don't remember the impact itself--but I do know that I wear a helmet without fail whenever I'm on my bike.

More bikes = less problems.

I understand and respect others' decisions not to wear one, though, and I don't think helmet use should be legislated. Can't we all just get along? We are all, by our presence as cyclists on the road, making the streets safer for all of us. This is one thing that everyone agrees on: more cyclists equals more safety (sources: here and here, for example). And in several jurisdictions that have passed mandatory helmet use laws, the number of cyclists has dropped as a result (source).

When less people bike, more people get hit, which begins to explain the astonishing statistics quoted in a 2001 New York Times article, reproduced here. According to the article, between 1991 and 2001, helmet usage increased, ridership declined, and the rate of head injuries actually increased by 51%. The article also suggests that perhaps riders wearing helmets have an inflated sense of personal security--they're wearing helmets, so they're safe, right?

This NYC street is not exactly bike-friendly.

Let's put helmets aside for a moment and ask: overall, how safe is it to bicycle? Well, based on per-hour fatalities, it's actually safer than driving or riding in a passenger car (source). In addition, several studies show that the health benefits of cycling far outweigh the risk. You can find one study here. Another, summarized here, here, concludes that "even in the current cycle hostile environment, the benefits in terms of life years gained, outweigh life years lost in cycling fatalities by a factor of around 20 to 1." And, of course, that's not even considering the social and environmental benefits of cycling.

What about the environmental impact of helmets? Helmets are made of some pretty unfriendly materials. The outside shells are usually made of polycarbonate, fiberglass, or carbon fiber, while the foam lining is expanded polystyrene (EPS). EPS does not biodegrade and is usually produced using chlorofluorocarbons--those compounds that have been poking holes in the ozone layer. Plus, helmets should be replaced after an accident or every three years, according to one manufacturer. But, obviously, riding a bike whether with or without a helmet has a lot less negative impact than driving a car.

Here in the United States, helmets treat a symptom, not the disease: roads that are only safe for people enclosed in giant steel boxes. They provide a measure of comfort, for sure, but that comfort allows us to lose sight of fighting the disease itself. Passing helmet laws allows lawmakers to feel as though they're doing something about bicycle safety without actually addressing the issues that are causing collisions to begin with. Let's work together, helmeted and helmetless alike, to make the roads safer for all human beings. You can help by riding your bike.

The management of strongly recommends that you wear a helmet when riding your bike, as the evidence for helmets increasing personal safety far outweighs any evidence to the contrary. The old adage "better safe than sorry" certainly applies!


A bike helmet with a dial adjuster for good fit.

If you decide to wear a helmet, here's some things to keep in mind. When you're buying a helmet, you'll notice that they range in price from ten bucks or so to several hundred dollars. So what's the difference between the cheap ones and the pricery ones? Protectively speaking, nothing. The more expensive ones are offering the following:

Low weight. Even cheap helmets are pretty lightweight these days, but really expensive ones practically float. They're designed for racers who are counting every ounce.

Ventilation. Expensive ones have tons of air holes without sacrificing protection, so your head doesn't get sweaty.

Comfort and adjustability. If you're lucky, a cheap helmet will fit your noggin just fine. But more expensive helmets often have more versatile adjustments, so you can really fine-tune your helmet to fit your head perfectly. As a result, they tend to be a little comfier. The lower weight and increased ventilation help with comfort, too.

If your helmet doesn't fit correctly, it may as well just be a funny-looking hat. Remember:

Your helmet should be level! Don't tip it back like you might tip back a hat. It needs to protect your forehead, not just the back of your head.

Your helmet should be secure on your head even before you buckle the strap under your chin. If it moves when you shake your head no or nod your head yes, adjust it so it doesn't (usually by moving pads or using thicker or thinner ones, or adjusting the size of the fit ring using a dial or adjuster at the back of the head) or try a different helmet.

Adjust the straps so that the Y on each side meets just below your ears. When buckled, the chin strap should be snug enough that when you open your mouth, you can feel the helmet pull down slightly. When you've adjusted everything correctly, you should be able to vigorously shake your head without your helmet moving at all. There's a detailed guide to fitting your helmet here.

A wide variety of helmets are available for sale at

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Comments from our Readers

Your family wants you to wear a helmet

Frreewheelin Rog(Rochester NY near Erie Canal), submitted 12/10/2009

Please buy a helmet from a veteran bike seller, not a web site. You may not wish to wear one, and we bike sellers shouldn't press you on it because then you will not want to shop at our store! But if you live with a non-cyclist, like your parents or spouse or kids, they will want you to wear one. Case closed.

Yes, I have lost customers who died riding, have seen people who changed their mind and bought a helmet after falling, etc. But I also have a friend who knows more about cycling than I do European guy who does not wear one. All the arguments are good, but the one I read said that 97% of bikecar fatalities were non-helmet wearing folks.

In 41 years of commuting, I have never crashed on my head. So be slow and don't annoy the bullies. Drive paranoid, I always say. You may have the right to ride fast and annoy people by law, but it is not good karma to do so.

Stop driving.

Stop driving.(Portland), submitted 12/24/2009

Question: if while hunting you accidentally shoot and kill a hiker, should you get mad at her for not having worn a kevlar vest? It's you, motorist, whose choice has put others in harm's way. While I'm getting from point A to point B on my bike, I'm also passively resisting a broken system. If you buy a car and start it up and kill me with it... it's on you. We are fragile creatures. Yes, I do choose to wear a helmet, but you can't require others to clad themselves in armor to better facilitate your irresponsibility.

UrbanCyclist response:

We agree completely that the motorists need to pay more attention to cyclists and it shouldn't have to be the responsibility of cyclists to protect themselves against motorists. And we would like to see tougher penalties for motorists that cause injury to bicyclists.

However, many cycling-related accidents are not the result of car-vs-bike situations, or are the result of recklessness or error on the part of the cyclist. Regardless of the cause of an accident, a serious head injury places a huge burden on family and friends, and in many cases, society at large by paying for long term care. It's not just ourselves as cyclists that suffer the consequences. Please ride safe and wear a helmet.

Helmets are good idea but ultimately it's up to the rider to wear or not

Elvis(New Jersey the armpit of the east), submitted 7/19/2010

Helmets are good idea but ultimately it's up to the rider to wear or not.

I see the sense in the argument that a driver knocking a cyclist off a bike is the problem, not whether or not the cyclist had a "skid lid". However, there are more hazards than bad drivers, including weather, potholes, curvy roads, and just plain dumb luck. Most of the hazards on the roads debris, potholes, shards of glass, etc come from cars, so again, it is the drivers fault if a crash happens. However, just because the crash is someone else's fault, that's no reason to not consider protecting yourself extra, if you can. That said, there are two issues here, at least the issue of the driver, not the experienced cyclist, being at fault for an accident, and the issue of would a helmet have made a difference? Helemts are not designed to protect you from being hit by a car or bus. They are designed to cushion the impact of your head in low-speed falls with the ground. This is why, by the way, so many advocates for helmets are those arguing that children should wear them. That's as may be and yes for children they surely will provide better protection, but this isn't because of the helmets, it's the situation of the children, who are smaller, going slower, have less distance to fall, and are usually not riding in the same type of traffic or conditions as an experienced adult rider, who, if riding for sport or transport, may find himself negotiating everything from city streets to open country lanes to suburbs and crowded overpasses jammed with slowly but erratically moving cars since no one who gets a drivers license apparently knows how to hold a straight lien in lane anymore. Thus you look at accidents with kids and helmets seem super. They help, but no one knows exactly how much, because most of the speeds reached by adult cyclists exceed the helmets tested impact speeds. I've got up over 40 mph going down hills and normally cruise between 15-20 mph or so. I know guys who can cruise at 25. And sprinting to dodge somethign in traffic the cyclist will often find himself passing a car, jaywalker, or other hazard with a burst of excelleration, the difference between which, and his previous constant speed, might itself exceed the speed at which the helmet is tested.

So let's be clear If a driver hits a cyclist yes, the injury is the driver's fault because he caused the accident. But there are other types of accidents a cyclist going down a curvy road can hit a hazard or slip on a slick spot. If I blow a tire or wipe out at 40 mph, I could be hurt just as if i was knocked over by a car, except for the risk of being crushed. That said, both situations exceed the helmets limits. it is not designed to protect a cyclist from getting hit by a car -- but will protect