Every day in San Francisco there are group bicycle rides or other events that peddle a healthy lifestyle, as this calendar shows. This week's highlights: TV Turnoff Week is April 23-29, and there's a much anticipated Critical Mass ride April 27. And stay tuned for www.bikesummer.org.

David Butcher rides a pedal-powered generator through Golden Gate Park on Earth Day, showing how human energy can be used to create usable electricity, as part of the Sustainable Living Roadshow during the Green Apple Festival on April 22.