This Saturday from noon to 6 PM, Chicago Area Mountain Bikers (CAMBr) and the Chicago Park District will host a party to celebrate the opening of Chicago’s first legal bike park, the Garden (3400 N. Rockwell). Settin’ Down Roots: The Garden Dirt Jam will feature open riding, bike repairs, bike demos by Kona, races, and other competitions for registered participants. Onsite registration is $10. Admission is $25 for CAMBr members, $30 for nonmembers. You can earn free admission by raising $50 in donations.