I don't care what your excuse is or how short the ride, there's no place for bicycles on a sidewalk unless the rest of civilization has been raptured into heaven and you're the only one left on Earth. It's dangerous for pedestrians, and it's dangerous for the cyclist. Ok for younger kids, but as an adult, you look like a total, ignorant nincompoop goofball when you ride on the sidewalk. If you can't ride on the road for whatever reason, then don't ride there. Find some other place to ride or take a bus. If you have to use a sidewalk to get from the road to wherever you're going, walk the bike! I say this as both a frequent pedestrian and a frequent cyclist.

One problem is that in many places including where I live, it turns out that there's no law against it, contrary to popular belief. I guess this is why every time I walk on my downtown street, I take my chances running the gauntlet of bicycles who seem to think of pedestrians as bumpers in a pinball machine.