Discover a fun, under-the-radar bike sport this weekend at Philly Pumptrack opening

While competing for prizes, participants learn about Philly history during the Fairmount Park scavenger hunt.

Hundreds of volunteers throughout the region cleared trash, delivered food and rallied for peace and justice as part of the nation’s largest and oldest MLK Day of Service.

The 14th Philly Naked Bike Ride takes place Saturday at 2 p.m. There’s no need to sign up and it’s free to ride.