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.

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  1. Camilo says:

    Hidden due to low comment rating. Click here to see.

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    • JoeG says:

      I agree. Helmets should be worn by all children and adults, not just when riding bikes, but during all waking hours. Kids out playing often fall, riding a bike or not. Adults have a high risk of slipping getting in and out of the bath tub, making helmet wearing while bathing a no brainer. Adults are also prone to tripping. I’m sure you would agree that safety goggles should also be worn by all adults and children. With kids throwing toys, bugs flying around, dust and debris blowing up during wind gusts, only an idiot would chance going blind by not wearing goggles. Prudent people would wear motorcycle helmets during all waking hours. They combine the best of both worlds, the safety of a helmet combined with great eye protection.

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  2. Thom says:

    Helmets are so much more accepted thanks to pro freestyle athletes. In freestyle, kids are more likely to wear helmets and pads because they know crashing is part of the process.

    I broke a helmet in a wicked crash eight years ago, and only got a sore neck and scratched forehead. Since then helmets are like seat belts to me, it’s uncomfortable to go without.

    And to the over-protective parents who think bikes are too dangerous: Let your kids fall down and get hurt sometimes. It’s part of a healthy childhood.

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  3. Tyler says:

    The nerd factor really…I had to wear a helmet before they were mandatory, so while I have survived to be a nerdy adult…it was the result of being a nerdy child.

    I hated wearing a helmet so I switched to rollerblading everywhere. Not cost, just no need to wear the safety equipment.

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  4. misterb says:

    Or because the states surveyed are coastal, the kids there are more wired than the kids in the middle of the country, and would be playing on their Wii, PlayStation and Xbox without the law. I know here in CA, fewer kids ride their bikes to school than did when I was a kid (2 generations ago) and also less than when my kids were young (1 generation ago)

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  5. Diggiti says:

    The Kid in the picture is Safer on a Bike with the Helmet.
    But CATNIP to a Bully !

    I would never EVER wear that.

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  6. zbicyclist says:

    In addition, with fewer cyclists, cycling is more dangerous (people are less likely to expect cyclists to be there).

    That’s sometimes cited as the reason there is so little improvement in safety with mandatory helmet laws.

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  7. MRB says:

    The potential problems I see with this analysis:

    * Bike helmet enforcement is near zero
    * Knowledge of bike-helmet laws is limited
    * Bicycle helmets do not prevent collisions.

    I suspect these are just as big a factor in mode choice as the cost of bicycle helmets.

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  8. Rob Rippengale says:

    I rode a bike with great enjoyment in Victoria BC, before the helmet law came into effect some years ago, and especially enjoyed the feeling of the wind in my hair. As the helmet law approached, I often noticed cars in my lane giving me much more clearance than they did the bicyclist in front of me who wore a helmet. Although wearing a helmet during an accident may prevent certain injuries, I wonder if wearing a helmet actually increases the chance of a serious accident.

    I would also add a reason many people don’t ride bikes specifically because of the helmet law – helmet hair.

    ps, I have not been on a bike since the helmet law began.

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