If you go slow and pause at every driveway or cross street, the sidewalk can be a safe place to ride. Sometimes it is the best option. Usually you are better off in the road. The two biggest issues with sidewalk riding are driveways and intersections. Most motorists will pull out across the sidewalk first, and then look left. They figure if there were any pedestrians on the sidewalk, they would have seen them directly in front of the driveway. Along comes a cyclist on the sidewalk at 15 mph and he's on the hood before anyone knows what's going on.

The second problem with sidewalks is they dump you out in the street at intersections. If you want to cross with the pedestrian light at slow speed, it can work. Don't enter an intersection at 15 mph from the sidewalk.