Sidewalks: Individual cities and counties control whether bicyclists may ride on sidewalks. CVC 21206
In the city I used to live in, you were not allowed to bike on any sidewalks.
In the city I live in now, you are not allowed to bike on the sidewalks of main streets but can on residential streets.
There are no state laws prohibiting it. Some cities have local ordinances banning it on some of their streets.
not legally, but people do it all the time