Gear Derailleurs (Tourney-24 speed Rear)

Derailleur gears are a variable-ratio transmission system usually used on bicycles, comprising of a chain, numerous sprockets of various sizes, and a means to change the chain from one sprocket to another. These bicycle gears are also called sprockets because they drive or are driven by a chain and are not driven by one another. Modern rear derailleurs usually comprised of a moveable chain-guide that is functioned remotely by a Bowden cable joined to a shifter mounted on the down tube, handlebar.