Plenty of cities have bike share programs: pay-as-you-go bikes that riders check out from a docking station, ride wherever, and then return to any open station. Now, dockless bike-share systems are rolling out in the U.S.

While these bikes have the same goal as their predecessor—to offer a quick, cheap means of traveling between transit hubs and riders’ final destinations—they feature one major difference: no docking station needed.

California-based LimeBike is one of the companies bringing unfettered bikes to U.S. cities and campuses. Strategic development director Maggie Gendron demonstrated how to unlock the eponymous lime green bike at last week's mobility showcase at the University of Pittsburgh. First, she used the company’s smartphone app to find a bike. Because she was standing next to it, that part was easy.

“In an ideal world, you would just walk outside and see a bike and you wouldn’t need the app,” she said. “But in some cities a bike might not be right in front of you, so you use the app to find a bike.”

Then Gendron tapped “unlock bike,” in the app and scanned a QR code on a small tag attached to the seat. Accompanied by a short, triumphant run of musical notes, the rear wheel unlocked. Gendron seemed delighted as she put her phone away.

“I think most of us who love bikes just get a certain sense of satisfaction during the day, of freedom, of being on a bike,” she said. “And every time I hear that sound [of the bike unlocking], I don’t know, it just puts a smile on my face.”

LimeBike is funded by venture capitalists, and covers all the costs of bringing bikes to a city. That’s really the power of dockless bikes, said Gendron.

“We really want this bike to be available to all people,” she said. “They really can go into any part of any city, you’re not waiting on funding to be able to build out the [docking] infrastructure.”

The idea of taking a bike anywhere without having to find a dock is exciting, said Scott Bricker, executive director of local nonprofit Bike Pittsburgh. But there are pluses and minuses.

“You could ride it anywhere ... and park it anywhere,” he said. “The issue is from what we’ve seen, the GPS isn’t really dialed yet. So when you try to look for a bike on your smartphone, often it’s way off the mark.”

There’s also the matter of theft or vandalism. When dockless bike-share systems debuted in Asia, companies flooded major markets with millions of bikes. Thousands were stolen; bikes were found buried in construction sites or hanging from trees. Riders often discarded them wherever, jamming sidewalks, annoying residents and flummoxing local officials.

There’s an easy way to avoid that city angst, said Ben Bear of stationless bike-share company Spin.

“I think it’s all about working with [cities] rather than taking a sort of rogue, devil-may-care approach,” he said. “I think that hasn’t worked very well in the ride sharing market.”

Dockless bike-share has a lot of potential, though exactly how it will roll out within cities is still a work in progress, said Bear.

“It’s a long game. But I think we all see sort of where it’s going, towards this multi-modal network that’s not just cars,” he said. “What are the exact steps to getting there and how do you create a sustainable environment for companies to operate? I think that’s what cities need to think about.”

Dockless systems have rolled out in Washington, D.C. and in Seattle, Washington, which shut down its docked bike-share system in March.

Bricker and others believe it doesn't have to be a binary choice. One company, called Zagster, has launched a hybrid system that allows users to leave bikes at a docking station, or lock to a stationary object.

In order to operate in Pittsburgh, any dockless bike-share company would need a city permit. Like most U.S. cities, Pittsburgh does not yet have regulations to govern those systems.