Boston’s Blue Bikes are pedaling south.

The city’s public bike-rental system will expand into Roslindale, Mattapan, and southern Dorchester over the next few weeks, Boston transportation officials announced Thursday.

Overall, the city will open 19 new stations. Riders rent bikes with a $99 yearly membership, or at rates that start at $2.50 for a 30-minute trip.

The city had previously announced the expansion plan but had not said where the stations would be located. While there are already more than 100 Blue Bikes stations in Boston, none were in Roslindale, Mattapan, or some parts of Dorchester, according to the current station map.


Later this year, another 30 stations will be put in place across Boston so riders will have additional dropoff locations. An additional 30 stations will be added in 2019, officials said.

Formerly known as Hubway, the bike-share system is owned by Boston, and the neighboring communities of Cambridge, Somerville, and Brookline, which each have their own stations. It is operated under a contract by the private company Motivate, which was recently acquired by ride-hailing firm Lyft.

The station expansion comes as traditional fixed-station bike-share systems like Blue Bikes are challenged by companies offering so-called dockless rental bikes that can be rented anywhere using a smartphone app to track down their location.

Dockless bike systems have quickly grown in several Boston suburbs but are banned from the Blue Bikes communities because of an exclusivity deal with Motivate. That hasn’t stopped some users from riding the bikes into those cities, however.

Adam Vaccaro can be reached at adam.vaccaro@globe.com. Follow him on Twitter at @adamtvaccaro.