Helmet laws and bicycle riding

Seems that helmet laws reduce bicycle riding, according to Carpenter & Stehr, Intended and Unintended Effects of Youth Bicycle Helmet Laws. Here's the abstract:

Over 20 states have adopted laws requiring youths to wear a helmet when riding a bicycle. We confirm previous research indicating that these laws reduced fatalities and increased helmet use, but we also show that the laws significantly reduced youth bicycling. We find this result in standard two-way fixed effects models of parental reports of youth bicycling, as well as in triple difference models of self-reported bicycling among high school youths that explicitly account for bicycling by youths just above the helmet law age threshold. Our results highlight important intended and unintended consequences of a well-intentioned public policy.

From the article:

Given that the foregone utility of riding a bicycle would seem relatively substantial, why do helmet laws lead to reduced cycling? There are several possibilities. First, the costs of helmet use are likely nontrivial for some youths. In addition to the direct monetary costs of bicycle helmets (usually between $10 and $40), there are likely to be substantial social costs (recall that survey evidence shows that youths do not like wearing helmets primarily because they are "uncool"). These costs are likely to be magnified if there are significant peer effects. Second, 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. Finally, note that there are several reasonably close alternatives to bicycling (such as skateboarding and in-line skating) that are not regulated in the same way with respect to mandated helmet use. Helmet laws change the relative prices among these activities, such that the robust reduction in bicycling we observe may be at least partially offset by increases in other related activities.

Not surprising that raising the cost of doing something reduces the demand.

There's evidence that bicycle helmet laws reduce fatalities. But what if they cause kids to switch to more dangerous activities that don't require helmets?

Comments

[Tom Grey]

Great note. If the helmet laws DO lead to more dangerous alternatives, that should be visible in total mortality rates.

But there are probably too few total deaths of high schoolers to show this, even if true.

[John Rohan]

Looks like helmet laws likely DO lead to more deaths - from obesity.