I don't bike because of safety. I can't afford for my laptop to be damaged in a spill. I can't afford to hurt my right arm or hand, or be in a hospital. Especially as a person who works for myself, and moves through the world in a body that's closing in on 40 years old... Riding in Philly is quite risky. I do sometimes, but its not my primary mode of transportation. I use to love to ride everywhere on campus in college - on paths with no cars. Almost no one else biked, but I rode everywhere. Even when the brakes fell off my bike! But now? In city traffic? Forget it!