NEW YORK (CBSNewYork) — New York City is looking for ways to expand bike sharing, but the solution might not come from the Citi Bike program.

The Bronx Staten Island and the Rockaways are just some of the areas still without the program, so the DOT will look into jump-starting expansion with competitors. That might mean offering self locking bikes that don’t need docking stations.

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“This is something we’ve seen other cities do,” said Joe Cutrufo, with Transportation Alternatives.

He praised the Citi Bike system, which has been used more than 53 million times since launching four years ago.

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He thinks a rival would do well to learn from the system’s example.

“We’ve seen it work in other places, but people in New York are used to standards of quality, safety, and service that Citi Bike provides,” he said. “So if the city does move forward with a dockless system, they need to adhere to that same quality that Citi Bike has.”

The DOT would demand that self-locking bikes not block sidewalks in between rentals. The bikes would beed to spread out among neighborhoods, and they would have to be affordable.

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The mayor’s office said other places usually charge $1 for every half hour.