Pedestrians on a sidewalk are expected to slow and look when they reach a cross street to see if there is any traffic coming and if not, then they are safe to cross. Cyclists on sidewalks tend to ride as if the sidewalk is an additional roadway lane and not slow and look for traffic at each corner. Cars expecting sidewalk users to slow and look and give way to them at a cross street may run over cyclists that don't slow at cross streets.

Secondly, when a car slows to make a right turn, it approaches pedestrians, walking in the same direction, from behind. Bikes are faster than pedestrians and as the car slows to make the turn, a bike may suddenly appear as it approaches and passes the car from behind. Cars making a left turn will look a bit ahead to watch for pedestrians at or near the cross street and may not look further down the sidewalk for an oncoming bike.

A cyclist that takes the lane or uses a bike lane on the road is expected to behave (and be treated) as a vehicle, not a pedestrian.

I say, if you must ride the sidewalks, use it as if you were a pedestrian, not a vehicle.

I may be wrong or it might be more of a local law, but I believe that cyclists crossing streets from sidewalk to sidewalk are required to walk their bike across. Maybe that's just for the safety of kids but it is something to consider.