I ride the street, but there is one area in town where the bike lane is directed onto the sidewalk. The walk in this area is extra wide and seldom used. I can think of a few other areas where you are forced on the sidewalk by rode design and you may have to ride to a point where there is a driveway to get back to the road. Some may jump down off the curb, but I don't on my commuter.
Sidewalks are for riding if you fit the following criteria children, parents riding with children, and a few others I can't think of now.
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"I've been dropped a lot of times, but it's never been because of my bike." DXchulo