Try Bike Shop free in your browser, with nothing to install and no account. Run a bike repair shop. Each ticket is a bike a customer brought in: a gear that is wrong for a hill, or a derailleur that will not shift. Count the teeth, see how far the bike rolls on one turn of the pedals, and find the gear that climbs the hill. Turn the barrel adjuster and the limit screws a quarter turn at a time, then pass the test ride.