From Wiki
Motor Division
The SFPD was one of the founding departments in the field of utilizing Police motorcycles, (along with their counterparts across the bay in Berkeley). The unit was founded in 1909, and has grown ever since. They are officially under the command of the SFPD Traffic Division. They participate in many duties such as traffic-enforcement, patrol, riot control, and special events and escorts. The only full functional department that utilizes the entire traffic fleet for escorts in the nation. No other metropolitan city utilizes all its motor bikes for escorts but SFPD. The entire 85 man unit is based at the Hall of Justice at 850 Bryant Street. Unlike most cities (which are tentatively smaller), they patrol as solo officers (hence the name SOLOS). They can frequently be seen throughout the city.The bulk of the unit is composed of Harley-Davidson motorcycles, and a sub-division exists that is composed of Honda dirt bikes (which is under the command of the Tactical Unit and not the same as Traffic), for city patrol and patrol in and around the area of Golden Gate Park. Otherwise, every one of the 10 main police stations in the city have 2 motorcycles under their command, used for patrol around their districts exclusively.
Officers on the Hondas were used to clear out revelers from Market St after the Giants World Series victory parade.