Example of a simple gear with idler?

A simple gear with an idler can be seen in a bicycle. The chain from the pedal goes to a small gear wheel (sprocket) on the rear wheel. There is also a larger gear wheel (sprocket) on the rear wheel, which is connected to the wheel itself. An idler wheel is situated in between the two gear wheels to keep the chain from slipping off the sprocket. As the rider pedals, the small sprocket turns, causing the larger sprocket to turn, and the idler wheel ensures that the chain remains engaged with the sprockets.