in the city of los angeles it is legal to ride on sidewalks. many people do, especially on busy streets without bike lanes. some adjacent cities dont permit riding on sidewalks ie santa monica.

i avoid biking on sidewalks as i know the dangers. some streets are dangerous too however so the best thing to do is try to bike on the safer streets. ive taken some falls on sidewalks earlier ie tree roots uplifting sidewalks, large cracks, debris, weird changes in sidewalk heights or unexpected curbs or barriers, projections from storefronts ie a concrete block holding a door open, or landscaping retaining walls of a few inches high, skateboards from people waiting for a bus, cars darting out from driveways, etc. street is more predictable. i find the biggest challenge is when im tired ie on way home from long ride or tired from work or not feeling well. then i might think i cant or dont want to ride in street, too taxing but in that situation ive learned sidewalk is worse.