As a pedestrian in a dense Californian urban core, I have mixed feelings about bikers.
Most bikers are reasonable, sensible bicycle commuters. They stay in the road, wear helmets, and follow laws. No skin off my nose. (ecologically friendly, fights obesity, blah blah blah blah blah)
But I've also had multiple encounters with bicyclists who feel they are entitled to switch back and forth between a wheeled vehicle moving significantly above normal walking speeds and a pedestrian who just happens to be on a bicycle. Usually with no notice and as is convenient for them. Not infrequently such enhanced-pedestrians can top 20 mph barreling down the sidewalk. Sometimes with cargo in tow. I have literally never even heard of there being any real consequences for such irresponsible and reckless behavior.
I understand why they do it. It's so convenient! Roads certainly aren't always designed for the safety of bicyclists. Yet, these are perhaps less than adequate reasons for irresponsible behavior.
More troubling to me is the role bicycles seem to play in the underground economy of the Bay. But that seems more an issue stemming from law enforcement's general disinclination to be interested in bikes and bikers at all.