The Hubway bicycle rental system gets rolling in Harvard Square, across from Harvard University. (Photo: Madeleine Ball)

The Hubway bike rental program launched officially in Cambridge on Wednesday with a “rolling” launch party that started in Brookline, had officials ride to Somerville and end in Cambridge.

Cambridge has eight stations but is promised rapid expansion by the Boston-based system; the city should end the month with 24 stations and 240 bicycles, helping reach the Hubway goal of 100 stations and 1,000 bikes in the region. In future years, the system could expand to Newton, Arlington, Watertown, Winthrop and Quincy, said Marc Draisen,  executive director of the Metropolitan Area Planning Council.

So far Cambridge bicyclists can find their rides in Central Square (at the post office across from City Hall; at Essex Street; and in Lafayette Square), in Harvard Square (at Harvard’s Kennedy School; on Brattle Street; and Dunster Street) and on the Massachusetts Institute of Technology campus (at Amherst Street; and at the Stata Center). The universities were major funders of the Cambridge stations.

“I’m thrilled to have Hubway here,” Mayor Henrietta Davis said in a press release. “It’s another option for green transportation in our city, and it’s great to have this bike-sharing system up and running in the metro Boston area — ahead of New York City.”

Even city councillors less identified with green initiatives (and bicycling in general) than Davis, Leland Cheung and Craig Kelley were eager to take part in the launch.

Tim Toomey, who is also a state representative serving Cambridge and Somerville, lauded Hubway as giving people in his cities “a new, healthy option to help them get around and stay active.”

The Somerville stations are at Beacon, Washington and Kirkland streets; in Union Square; and at Somerville City Hall.

Citizens were excited as well, taking and sharing pictures from the Stata Center and across from City Hall and literally cheering the system’s arrival. “Yay for Hubway stations in Cambridge!” said a Twitter user going by the name Donnal. “Now I need a pack mule service to help me carry large heavy items home.”

But, of course, not everything was perfect.

“And then in Harvard Square, there’s a Hubway cyclist on the sidewalk,” said a Twitter user named Erin at 3:32 p.m., only four and a half hours after the post office launch ceremony. “Come on, people.”

Harvard’s Commuter Choice Program created a video on how to use the Hubway system: