12mph when you hit a pedestrian is not exactly a soft landing. Besides that, it's really, really tough on the pedestrians and can easily send them away in an ambulance. You're not expected to be on a sidewalk and so it is dangerous for you and for pedestrians. At least stay on a bike path or Multi use path instead of a sidewalk.

There are stats about pedestrian/bike accidents on sidewalks, go have a look. IIRC, it's more dangerous for both for a cyclist to be on a sidewalk. Besides that, it's common sense.

I'll grant you that it's probably safer for you when you hit a pedestrian than it is for the pedestrian and that there may be less risks to you getting hit by something bigger than you are (i.e. car) but it is far from safe and you just don't belong there. Go read the ordinances of the city whose sidewalks on which you intend to ride.

The worst crashes I've had are on multi use paths, by far. A sidewalk would have to be worse.

J.