A regional note for San Francisco: the bikers here aren't helping things. We seem to have a disproportionate number of asshole bikers who seem to think they are entitled to fly through stop-signs as 10/15 mph. As a person who both bikes and drives a lot in the city I see both sides of this coin. I understand that coming to a full stop is an expensive operation for cyclists... but approaching a 4 way stop with cars already at the intersection and then suddenly deciding that you're a magical cyclist that doesn't need to obey traffic laws is both dangerous and pisses of motorists which only increase tension for all people involved.