Riding in California, you have to have your wits about you. Look out for the sign "No Right on Red".
If you want to go straight ahead, you get in the second lane and let the right turners go between you and the curb.
If you are waiting to go ahead on a red, and there is the blast of a horn, it'll probably be a giant pick up truck.
Wave at him and get out of the way,,, into the middle of the second lane.
I rode round San Francisco. There are much less cars than in London. Left on red in London would be a nightmare. Even if it were cyclists only, I'll lay a pound to a penny there would be a cyclist down on the first day.
New York is NO right on red. Much safer for cyclists.
More wits to keep about you in sunny Calif. The lights change from red straight to green. So watch the transverse direction for their amber lamp before their red.
Their are NO traffic islands. Its lamps after lamps after lamps.