Get out of the gallery and onto a bike this afternoon to witness firsthand how location is often the only difference between an art exhibit and vandalism. TIME’S UP!—the 20-year-old grassroots environmental group—has organized the Graffiti Ride to promote non-polluting transportation and reveal some often overlooked masterpieces at the same time. Jake Dobkin, who has scouted street art for 10 years, will lead the 10- to 15-mile tour past well-known murals and to more hidden locations throughout Bushwick, Williamsburg, DUMBO, and downtown Brooklyn, as well as spots in Queens and East Harlem. Along the way, learn about the history, social implications, and shifting trends of New York graffiti culture. At 2, meet at 99 South 6th Street, off Bedford Avenue under the Williamsburg Bridge, Brooklyn.

Sat., May 29, 2 p.m., 2010