If a City-installed bicycle rack causes damage to the sidewalk, the City is responsible for repairing the sidewalk. (Sidewalk racks should be installed in crack-free cement only to prevent sidewalk damage and maximize the security of parked bicycles.)
If a private party causes damage to a bicycle rack and a police report is made (such as after a car crash), the City will hold the party responsible for the repair. If no responsible party is identified, the City will repair the sidewalk. If a property owner receives a notice from the City requiring sidewalk repair (per the State of California Streets and Highways Code), the property owner is responsible for reinstalling the bicycle rack as part of the overall repair, just like other street furniture and signage. The cost for removing and replacing a City-furnished bicycle rack is small compared with the overall cost of sidewalk repair.
The State of California Streets and Highways Code, 1911 Act (Division 7, Part 3, Chapter 22, Articles 1-3, Sections 5600-5630), stipulates that the owner of the fronting property is responsible for maintaining the sidewalk in good and non-hazardous condition. There is an exception for when sidewalk damage is caused by City action (like root damage from a City-planted tree). In these cases, the City is responsible for repairing sidewalk damage.