Well D-O-G, Lemme tell ya that while riding in the city is at first scary and unsafe, once you get your bearings and learn the rules of the road, it becomes some of the best city riding you'll do in your life simply because SF has such varied terrain and is small enough to get around on your bike efficiently but large enough and crowded enough so it takes a little more time than an empty 7x7 square would. I've got to tell you, SF cyclists are savvy because if they aren't, they're dead. That being said, there is a high occurance of cyclist vs. vehicle accidents, mostly getting doored and being hit by careless motorists. The de facto statistic is that if you ride in the city for three years you are gauranteed to be hit by a car and doored at least twice but this is only true if both parties aren't paying attention.