PHOTO BY MIKE KOOZMIN/SF NEWSPAPER CO.

Check out this week's cover story on the 20th anniversary of Critical Mass, then proceed directly to the festivities below

WEDNESDAY 26

East Bay Ride, meet at West Oakland BART station, 11:45am. Ride along the east shore of the bay to the Rosie the Riveter monument in Richmond.

NOIZ Ride, McKinley statue on the Panhandle at Baker Street, noon. Bring food, drink, and layers for a several hour, non-strenuous ride featuring three live bands.

Shift Happens book release party and discussion, Main SF Library, Latino-Hispanic Room, 100 Larkin St, 5:45 p.m. Discuss Critical Mass and this new book with its writers.

Book release concert, Great American Music Hall, 859 O'Farrell, SF, $15, 8pm. Featuring Seaweed Sway, Aaron Glass and Friends, and Kelly McFarling

THURSDAY 27

Mosquito Abatement Ride, Meeting place TBA near 16th & Valencia, SF. One-hour rides with a cycling city contractor.

NYC Critical Mass discussion and video, 518 Valencia, SF, 2pm. Hosted by Times Up New York City.

Bike Polo, Jose Coronado Playground, 21st and Shotwell, SF, 7-9pm. Play with locals and visitors, share a beer.

Bikes, Bands, and Brew: CM's 20th Bday party, CELLspace, 2050 Bryant, 7pm, $10-20. Bike cultural offerings and music by Grass Widow, Apogee Sound Club, The Rabbles, and Future Twin.

FRIDAY 28

20th Anniversary Critical Mass Ride, Justin "Pee Wee" Herman Plaza, Market and Embarcadero, SF, 6pm

Vintage Bicycle Film Festival, Oddball Films, 275 Capp, SF, $10.

SATURDAY 29

International Critical Mass Symposium, California Institute of Integral Studies, 1453 Mission, Rooms 303/304, 5-8pm. Event will include an open mic and CM20 Anniversary Week photo contest at 7pm

SUNDAY 30

Farewell Bike Ride and Party, 1pm departure from 518 Valencia, 2pm at Ocean Beach. Bring food and drink to share with your new friends and listen to bands on Rock the Bike's pedal-powered stage.

For more events and details, visit www.sfcriticalmass.org