From the SF Bicycle Coalition:
Bike to Work Day is the premier city-wide bike event of the year! Tens of thousands of people will hop on a bike and pedal to the office on Thursday, May 8, 2014. The San Francisco Bicycle Coalition hosts the most robust Bike to Work Day event in the Bay Area with over 25 Energizer Stations, urban bike safety classes and workshops, parties, raffles and giveaways leading up to the event to celebrate biking in San Francisco.