1. RD TZ50 Derailleur with Hanger Mount Give your sports bicycle a twist with this derailleur 2. The derailleur is made from metal and is black in colour. It comes with a wall mount which can help it to be placed on a vertical surface. 3. What is a Derailleur? Derailleur gears are a variable-ratio transmission system commonly used on bicycles, consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another. 4. derailleur to give an extra gear boost to your sports bicycle. 5. The RD-TZ50-6-GSD Derailleur with Bracket Mount is another outstanding addition products. cycling parts, especially shifters, derailleurs, sprockets, and brakes.