Derailleur gears a detent or ratchet mechanism which stops the gear lever, and hence the cable and the derailleur, after moving a specific distance with each press or pull. Indexed shifters require re-calibration when cables stretch and parts get damaged or swapped. On racing bicycles, 10-gear rear cassettes appeared in 2000, and 11-gear cassettes appeared in 2009. Most current mountain bicycles have either. Many modern, high-end mountain bikes have begun using entirely one chain ring drivetrains, with the industry constantly pushing the number of rear cogs up and up, as shown by SRAM's Eagle groupsets (1 by 12) and Rotor's recent 1
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