There are compelling cases for and against mandatory helmet laws like the one we have in King County (for: studies show that helmets are very effective at reducing head and brain injuries; against: other studies show that helmet use prompts cyclists to take more risks, and discourages new riders from riding bikes).[pullquote]I'm not going to put on a helmet that's been used by dozens or hundreds of other sweaty people of unknown sanitary standards, any more than I'm going to wear clothes I found on the ground.[/pullquote]

However, one clear down side to helmet laws is that they discourage bike-sharing systems like the popular programs in Portland and Washington, D.C., where helmets are not required. Bike sharing programs are designed for short, spur-of-the-moment trips: You grab a bike from the rack, go where you need to go, and lock it into another rack.

I don't know about you, but I'm pretty unlikely to carry a helmet with me everywhere on the off chance that I'll decide to take a quick, unplanned trip down the street (people make fun of Josh for carrying his helmet around after he locks up and runs errands). And I'm not going to put on a helmet that's been used by dozens or hundreds of other sweaty people of unknown sanitary standards, any more than I'm going to wear clothes I found on the ground. Thus, the conundrum: How do you promote bike-sharing in a city with a mandatory helmet law?

So far, the Atlantic reports, you don't. Not one city with a mandatory helmet law has a bike-sharing program. But that could change, as cities like Vancouver and Seattle explore bike-sharing options. Although helmet vending machines are the most frequently cited option for making helmets accessible to bike-sharing cyclists, they aren't really practical; once you've bought the helmet, you have the problem of toting it around with you every time you may want to use a bike. Given that you can't try a helmet dispensed from a machine on for size and comfort, you'd be better off just going to a bike shop.

But there are alternatives.

One is to attack the helmet problem head-on by providing helmets that, in effect, clean themselves. A prototype vending machine called the HelmetStation dispenses "removable helmet canisters" (as the Atlantic puts it) that would be cleaned and sanitized every time they're returned. Treehugger notes that the helmets can either be returned or purchased and kept for later use.

Another is to make failure to wear a helmet a secondary offense, like some states do with seat belt laws, in which an officer can't stop or ticket a cyclist for failing to wear a helmet unless the cyclist is violating some other traffic law.

A third option is to make helmets optional for bike-sharing customers. This doesn't strike me as particularly A) fair (why should bike owners be penalized for owning bikes?), B) safe (mixing infrequent or inexperienced cyclists with no helmets with more experienced helmeted cyclists could be a recipe for disaster), or C) even legal (exempting bike-sharers from helmet laws would be like exempting rental-car drivers from seatbelt laws).

The most radical option, implemented in cities like Tel Aviv and Mexico City, is to simply repeal the helmet law for everyone. Opponents of helmet laws (and I'm one of them) argue that  they encourage a false sense of safety (or, conversely, a mentality of fear) among cyclists. More importantly, helmet laws often serve as a barrier to entry: In New York , where there is no helmet law, cycling has more than tripled since 2000 while the number of deaths and serious injuries has remained steady.

Interestingly, the New York Times reports, helmet use is widespread even without a law. That may be because the city provides free helmets to any cyclist who wants one---a policy that might go further toward promoting safety than draconian laws to punish those who fail to wear a helmet.