Do Bike-Helmet Laws Discourage Bicycling?

In a new working paper called “The Intended and Unintended Effects of Youth Bicycle Helmet Laws” (abstract here; pdf here), Christopher S. Carpenter and Mark Stehr offer a surprising conclusion: while mandatory helmet laws have led to increased helmet use, and while helmet use has been shown to reduce bicycle fatalities, such laws also seem to lead to a decrease in actual bike riding.


Carpenter and Stehr lay out their case compellingly. They exploit a convenient variable: the fact that helmet laws exist in only 21 states, pictured here:


While conceding that these are primarily “coastal” states, the authors note that they cover more than 50 percent of the U.S. youth population.

Their research first confirms earlier research that “helmet laws significantly reduced bicycling fatalities among youths age 0-15 (i.e., youths who were directly treated by most states’ age-16 helmet laws) by about 19 percent.”

Their research further suggests “that helmet laws significantly increased youth helmet use by 29-35 percent.”

But: “There is also robust evidence for an unintended and previously undocumented mechanism: helmet laws produced modest but statistically significant reductions in youth bicycling participation of 4-5 percent.”

The authors offer three explanations for why this may be true:

1. The cost of helmets, both monetary and social — i.e., Helmets are uncool, so if I’ve got to wear a helmet to ride my bike, I’ll find something else to do.

2. “There is evidence that youths have suboptimally high discount rates (Gruber 2001), such that some youths might place too little weight on the expected gain in future utility from the prevention of injury or death relative to the costs of wearing helmets today.”

3. Bike-helmet laws lower the price of activities similar to biking — skateboarding, rollerblading, etc. — that do not require a helmet.

These seem perfectly sensible to me, but I might add a couple other possible explanations:

1. Helmets are a hassle.

2. Helmet laws make cycling seem more dangerous than we used to think it was. Therefore, a certain kind of parent develops a bias against it, and no longer encourages his or her kids to ride a bike — or, perhaps, never even bothers to buy the kid a bike.

Whatever the case, a downturn in bike ridership may strike some people as a grievous strike against the American character. On the other hand, it’s great news for the likes of Nintendo, Sony, and Microsoft.


So let's see....states enact helmet laws and over a period of time kids are riding less. That's a general coincidence, but would also suggest that kids are perhaps strapped into SUVs and driven everywhere by paranoid parents, playing more video games, riding an expanding number of other wheeled toys or maybe just not keeping track of their time very well.

It's a shame that neither economists nor nutritionists can ever understand the difference between causation and correlation -- couching it in jargon about "costs", "future utility" and the like doesn't fool much of anyone other than their colleagues.


#2 i have to agree. Bicycling is perceived as more dangerous by parents of young children.



Helmet laws are ineffective and wasteful. Police must now spend time busting kids for riding without a helmet? What's next for our nanny state, helmets for walking?


It's not just helmets. A bike mean freedom to a kid. She can go where she wants to anytime. Alot of parents today are uncomfortable with allowing their kids that kind of freedom, irrespective of its safety.

Having your child sit at home with videos, or Xbox, or Wii, getting obese is more secure for some parents, than allowing these kids to go outside, have fun, and travel a mile or two - or more - from home with friends.


I agree that the cost of helmets may be a factor, we have 3 kids who grow quickly and the cost of getting each kid a new helmet each year adds up. The boy doesn't want to wear the girls helmet of course and people frown upon sharing old helmets with neighbors and even if you use them, some old helmets are not very comfortable for kids if the pads fell out, etc.

Krt186 may be on to something sort of. I agree that an association does not mean that the laws CAUSE a decrease in riding, we need to find factors which would lead to a decrease that are more or less frequent in state's with helmet laws. One other possible explanation for this association is that perhaps most state's with helmet laws have also enacted state and local programs to encourage safe biking, built more bike paths, etc. This may have lead more kids in those states to ride more and other states, without helmet laws, have roads and paths that are growing less safe and bike friendly. My city, Madison, WI has built many great bike paths in recently years and as a result, we feel safer and use them with our kids. Without such things, I don't think my kids would bike as much.



Helmets are a hassle? Really? There's literally TWO motions required. Put it on your head, clip the strap. If that's a hassle . . .

Mike Stead

In NZ (my home) helmets have been compulsory for nearly 20 years, with nearly 100% compliance. Have cyclist deaths/serious head injuries decreased, per hour ridden / million KM ridden / pick your metric?

Answer: NO. NO. NO. A hundred times NO.

All that has happened is that fewer people cycle (about 20-30% fewer), so more people drive, we got fatter / lazier / more car-bound / less community-spirited, etc. etc.

The standards helmets are tested to is pathetic. 5kg dropped from 2m. Most cyclists I know weigh more than 5kg, and move faster than a drop from 2m. Only a motorbike helmet will actually do any good in a serious head-object impact, but cyclists won't wear them.

Western Europe knows all this intuitively, hence no helmet laws. They value individual freedom of choice above well-meaning but misguided legislation. they point to NZ as how NOT to encourage cycling and safety in numbers (the only true way to make a very safe activity a bit safer.)

The cost argument is bunk as well. Studies of the health benefits of regular cycling show they outweigh the costs of accidents by 20:1. An unhelmeted cyclist is doing your country and its budget a favour by staying fit, not polluting our towns, and not costing foreign exchange in petroleum purchases.

Cycling is safer than walking, and far, far safer than driving per hour spent doing it. Yet no-one (except a few Japanese trials) have suggested pedestrian or car helmets.

The "I smashed my helmet, therefore it saved my life" argument is also anecdotal, unscientific nonsense. All that proves is that your weight and velocity greatly exceeded the design parameters of the helmet. Big surprise! Pediatricians are not physicists or statisticians or accident experts. They should not make claims or be trusted to speak about matters they know nothing about. Would you take a lesson in road safety from a mechanic?

At best a helmet might save you a few stitches, but there is serious science that suggests that as it greatly increases your head's impact area, you are more likely to suffer a rotational brain or neck injury, which is far more likely to kill or cripple you than a straight-on impact injury.

The use case that would definitely, 100% guaranteed benefit massively from helmet wearing passengers. They don't have the aerobic heat generated to dissipate, so could wear a much more protective helmet as well.

Make car users wear helmets. Then I'll wear one on my bike. Not before.

Bikes used to be and should be again for the masses, not lycra freaks on Sundays only. In Denmark bikes are like vacuum cleaners or toasters - everyone has one and uses it often. They are no big deal.

You don't need a helmet to ride one. Period.



Iljitsch van Beijnum

Anyone suggesting that adults should wear a helmet to ride a bike would be laughed out of the country in the Netherlands.

I used a bike nearly every day for 20 years, never got hit in the head once.

East Coast Phil

The kid in the photo is actually not safer with that helmet. The chin strap is hanging loose, and the helmet looks like it's too big. Maybe this is his way of being cool: I'll wear the helmet if I have to, but I'll make sure it doesn't protect me.


i've always found it strange that a large portion of austin cyclists do not wear helmets while cruising the congested city streets. considering that the weight class between a car and a cyclist is so vast, it would be like a lightweight sparring with a heavyweight, sans head gear. no contest. the same goes for motorcyclists. why they are so resistant to helmet laws is beyond me.

regardless of perceived risks, it just seems like good sense, for the most part, to wear a helmet when cycling.

Chris Wilby

We need the law to have helmet laws in place, who cares if there are a few not cycling, they're safer off the bike then.

When I was bringing my kids up and instilling helmet use it was ok till a certain age when it was uncool to wear a helmet but I didn't even have the law to help me make the case for it.

Its probably uncool on a motorbike too, so how about repealing that law so we can encourage more guys on motorbikes.

James Prideaux

Yes, the chin strap is not properly fitted --

However, take another careful look -- I think that the child in the photo is on a bicycle with training wheels.

Does anyone think that makes sense?



I live in one of the helmet law states, and rarely see kids in my neighborhood wearing helmets. I bet their parents have no idea about the helmet law.

For kids who really get into cycling....all the pros wear helmets now (wasn't so even 10 years ago) and helmets are required for pretty much every kind of organized bike event you can imagine (races, charity rides, trail days, etc...).

How can it be uncool when Lance wears one?

A cheap helmet costs $10 and I bet most kids have a helmet of some kind in the garage already.


If we look beyond the US, we find that countries with lowest rate of helmet use have lowest rate of bicycle fatalities and serious injury.

Until the helmet-lobby can explain this inverse correlation, we should treat bike helmets as no better than snake oil.


The sports equipment industry is not helping to promote adoption. I recently tried to buy a helmet for my big head and all they had at the store was size U (for "universal fit"). I wouldn't have lasted five minutes with that sizing toggle sticking into my skull.


A few things:

- While Washington state does not have a state-wide helmet law, most of its major cities do and the law applies to everyone, not just kids.

- Living in an apartment is not a block to biking. People who live in an apartment store their bikes in the parking garage or on their balcony. In the Pacific Northwest, having a bike on your balcony adds to your social cred -- it's like waving a flag that says "I care about the environment AND I'm in shape."

- Living in an urban environment is not a block to biking. My parents taught me the rules of the road when I was a kid, biked with me to make sure I understood them, then let me bike on my own. I biked to elementary & middle school along busy streets, using the sidewalk when one was available, and never had a car try to run me over. The traffic wariness I developed as a kid bicyclist really helped me when I learned how to drive a car, since I'd already had years of practice anticipating how people drive.

I live in Seattle, a city full of steep hills, and have not observed this downtrend in bike riding to be worrisome. Kids still bike around my neighborhood. Hipsters in Portland and Seattle (usually between ages 19-35) bike everywhere, we even have traffic and political problems with some of the bike groups like Critical Mass. Our bus system has bike racks so that people can use the transit system to circumvent large hills. Adult bike commuters are a frequent sight and our city has many tax breaks that encourage employers to push bike/bus commuting.

Based on all that, I call red-flag-waving fail on this post.



I want a rule that says if you don't wear a helmet, then you must carry disability insurance.

I don't mind people volunteering to take the risks, but I want them to *take* those risks, not to shuffle them off on unrelated taxpayers in the form of taxpayer-funded health care, housing, food, etc. for the few that are permanently disabled as a result of their choice.


I'll add to the chorus of "correlation vs. causation." Until we control for many other conditions with kids, i.e. why they ride a bike (going to school, friends, fun), the costs of bicycles, parental attitudes, etc. etc., we may not know with any certainty why use has decreased. Since some of this is speculation, I, too, would speculate that the presence of other recreational or transportation alternatives may depress bicycle usage. Many of us grew up seeing a bicycle as an essential element of our lives as kids and the only means for getting around. Now, there are plenty of competitors for what amounts to essential and the ubiquity of kids being driven everywhere for everything can be factors, too. Also, did I miss something, or did the authors also report bicycle usage increases or decreases in those states without mandatory laws?


Only a generation ago, I rode my bike around the neighborhood at 8+ years of age - helmetless. Now, I won't let my kid do it even with a helmet. Its not paranoia people - its fact - predators are out there and they are looking for the kid riding his bike alone. As a parent, I can't accompany my kid on every bike ride, so he rides less - I wish it were different, but predators are getting bolder and laws are only enforceable AFTER you find your kid dead in some trunk at the bottom of a lake. Sorry, you can take all the chances you want with your kids, I will pass.


Cost? About 50-cents per week for 1 year. I don't think that's a valid issue.

Enforcement: I don't care who wears a helmet as long as non-helmet wearers sign a release saying that neither they or any one representing their interests will ever file a lawsuit related to head/neck/brain or general-mobility injuries they might incur while riding.

The point is not bike rider safety - that's up to the rider. The reason for the helmet regulation is to help protect municipalities in this litigious age.