In one episode, Spoiled Kid, Andy and Barney seriously enforced NOT riding a bicycle on the sidewalks.
However, in another, Loaded Goat, Opie comes around the corner on his bike, runs into Andy and Barney on a sidewalk, and not a word was said. Yet another writing inconsistency. And as I have remarked before, there was someone on the show's staff in charge specifically of continuity. Too many different writers did "spoil the broth."