NEXT YEAR, anyone with a credit card will be able to grab a bike in downtown Portland, pedal to their destination, and then return the bike to a high-tech locking station.

But here's the big question: Will they also be wearing a helmet?

Last Wednesday, December 12, city council approved a contract with Portland-based Alta Bicycle Share to roll out a program that will install 75 stations containing 750 rentable bikes throughout the central city. Bike-share systems already exist in 26 other American cities, and the aim in Portland is to replace short car trips with bike rides instead.

Commissioner Amanda Fritz, a retired nurse, is concerned about all those tourists, office-dwellers, and casual riders hitting the streets without helmets. She signed off on the contract only after spearheading an amendment: Alta must study a way to include helmet rentals.

The helmet study plan doesn't mean Portland's bike share will be required to include helmets. Instead, Alta must draft a list of options showing how bike-share customers could acquire helmets and how expensive such a plan would be.

The city is dipping its toe into dicey waters. Bike advocates have long battled over whether it's safer to require helmets—which, certainly, keep riders safe from certain types of head injuries, but often deter people from riding at all. Studies locally and internationally show that biking is safer when more cyclists are on the road.

"We wish them the best in being able to find a helmet-delivery system that is affordable," says Bicycle Transportation Alliance's Gerik Kransky. "But we believe bike share will be safe and should not really require a helmet."

Commissioner Fritz says she still does not support the bike share program (a point she made clear as council's sole "no" vote on the plan in 2011) but that helmets could make some new riders feel safe. "If one of the goals of the program is to encourage people to ride who are not comfortable doing so all the time, it seems to me that providing helmets might encourage some to try cycling," writes Fritz, via e-mail.

No American city requires bike-share riders to wear helmets. But bike share has stumbled in other countries with helmet laws. The low ridership of bike-share systems in Australia has been partially pinned on its helmet requirements. For helmet-requiring Vancouver, BC, Alta is pitching a plan to install helmet-rental stations at its upcoming bike-share stations.

Portland could potentially install helmet-rental stations, but it would likely drive up the cost of the project. The start-up costs for Portland's bike share is $4.6 million, covered entirely by federal funds and private sponsorship.

Portland could go the route of Washington, DC, and ask bike shops to discount helmet purchases for bike-share users. New York City, whose delayed Alta bike-share system is supposed to launch this May, is offering bike shop discounts and handing out 50,000 free helmets.