Derailleur gears Derailleur gears 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. Although referred to as "gears" in the bike world, these bicycle "gears" are technically "sprockets" since they drive or are driven by a chain, and are not driven by one another. Modern front and rear derailleurs typically consist of a moveable chain-guide that is operated remotely by a Bowden cable attached to a shifter mounted on the down tube, handlebar stem, or handlebar. When a rider
International Federation for the Promotion of Mechanism and Machine Science are: International Federation for the Promotion of Mechanism and Machine Science International Federation for the Promotion of Mechanism and Machine Science (IFToMM) is an organization that supports international exchange of researchers and engineers from the wide range of discipline related to Mechanical Engineering. To promote research and development in the field of Machines and Mechanisms by theoretical and experimental methods, along with their practical application. It was on September 29, 1969m at the Second World Congress on Theory of Mechanisms and Machines which took place in Zakopane (Poland), that two scientists, Ivan Artobolevski (USSR) and Erskine Crossley (USA), proposed to