WASHINGTON, DC, is treading on Portland's sacred turf as America's most innovative bike city. The nation's capital followed the lead of cities like Paris and Barcelona last summer when it launched a fleet of 120 shared bikes. Now Portland is considering kicking its own bike-sharing system into gear with 660 bikes that would be rentable like Zipcars—the Portland Bureau of Transportation (PBOT) just needs to figure out how to pay the $2.64 million startup cost.

Portland has long experimented with the idea of bike sharing. Back in 1995, grassroots bike activists and the Community Cycling Center launched the Yellow Bikes Project, which aimed to place 1,000 free bikes on Portland's streets. Anyone could ride the bikes around town for free and many infamously wound up at the bottom of the Willamette.

This time around, only subscribers with credit card information safely on file could check out bikes. While the idea is still in the initial planning stages at PBOT, transit planners are looking covetously to Paris, where racks of rentable bikes reside every 300 meters in the city, says PBOT Manager Steve Hoyt-McBeth.

"Bike sharing does not have a real robust constituency here at this point," says Hoyt-McBeth, "But this could replace some car drivers long-term since people can try out bike riding."

Hoyt-McBeth's exploratory plans recommend placing shared bikes every few blocks downtown. With all public entities slashing budgets, bike sharing might have to look elsewhere for its $2.64 million start-up costs. Last year, the city cancelled its search for a big corporate vendor who could run the program, but the idea is spinning around again.

Subscriptions cover 80 percent of other cities' bike-sharing programs, says Hoyt-McBeth, but Paris and DC also sold ads on the new bike racks to cover their steep start-up costs. That approach would be illegal in Portland thanks to a policy that bans advertisements on city-owned bike racks downtown. The Rose City's program might look more like Barcelona's, which funds its 6,000 bikes with parking and car fees.

Two other unsolved hurdles are theft and reassuring inexperienced tourists. Roughly a third of Paris's 20,000 shared bikes have been demolished or disappeared, while bike advocates say unleashing helmet-less tourists onto Portland's busiest streets could be a recipe for disaster without more bike infrastructure.

"It would certainly put significant pressure on the city to invest in bike infrastructure. You're not going to have newbies feeling comfortable biking downtown on streets with all those cars," says Jonathan Maus, editor of BikePortland.org.

The city will host bike-sharing demonstrations through August, the first being downtown at the waterfront on August 14 from 10:30 am-3 pm.