The bike is just another mechanical element of the show, it has nothing to do with actors knowing how to ride it. sometimes it works sometimes it doesn't. I've been there when the targets that come down from the celing don't go back up, and get stuck there for the whole show. The bike runs on a track on stage. When the bike doesn't work, the show goes on as normal, except that the actors dont exit through the time portal, it kinda throws you off cuz it goes from stage to a bike scene in the movie.