When I'm riding on a sidewalk (a rarity) I go down to pedestrian speeds. Any bike rider with a modicum of experience can easily gear down to pace pedestrians in a split-second.
Unless your bike is motorized, that is.
![Wink ;)](./images/smilies/icon_wink.gif)
Maybe half the car drivers in this city are willing to hit the brakes when confronted with the choice of slowing down and waiting to pass a bike safely and just trying to slide by, hoping the bike doesn't hit a bump and careen into your right side-view mirror, or under your bumper.
I generally just don't take the chance. If I deem there isn't room to safely pass me, I position myself so that the car doesn't have the option. Either he hits his brakes or he runs me down. When given that option, so far 100% of drivers hit their brakes. Though this tends to piss people off, it generally just means they are inconvenienced 2 or 3 seconds, which they easily make up after they safely pass, and are back to tail-gating the car that was in front of them in no time.