Sidewalks are not for bike riding. Not now, not ever.
Please, we know you love your bike, but pleeeeeeease, don't do it on the sidewalk.
The sidewalk is the only safe place to walk. Everyone wants to keep it that way.
We know you "can" ride your bike on the sidewalk. You might have learned to ride a bike on the sidewalk. But that was when you were a child. Now you, me, everyone has grown up. We have to behave like grownups, not like a 6-year old. It's a challenge, we know. But riding your bike on the sidewalk is an antisocial activity, and dangerous too. And, we repeat, it really scares the crap out of the pedestrians.
Thanks. When we see someone who stops at the corner and walks their bike on the sidewalk we actually go over and thank them. And that makes everyone feel good.