As a pedestrian I've had more bad encounters with bicycles in San Francisco than cars.

I'll agree motorists are more careful than cyclists. Some cyclists will pass you at 20km/h and 5cm distance, motorists will keep much more distance than that.

But they have more speed and more weight too, and their greater distance doesn't compensate, so if you look at who kills you with their carelessness, the answer is plain: Motorists.

Cyclists are careless and give you a bruise or a fractured wrist.