Blue Cross Blue Shield of Massachusetts is sponsoring free Bluebikes every Sunday in May as part of its second annual “Miles for Mental Health” initiative – itself in recognition of Mental Health Awareness Month and National Bike Month. Blue Cross is the sponsor of Bluebikes, which is owned by the communities and operated by the car share company Lyft.

The so-called Adventure Passes are available across the Bluebikes system’s 13 communities, including Cambridge, Somerville, Arlington, Watertown, Boston, Brookline, Chelsea, Everett, Malden, Medford, Newton, Revere and Salem.

Riders can take advantage of free unlimited, two-hour Adventure Passes each Sunday in May by downloading and opening the Bluebikes App on a mobile device and selecting “Adventure Pass.”

The code for a free two-hour Bluebikes rides this weekend is BLUECROSS21.