In bicycles, the shifting system is the key to speed and comfort as well as stability and safety. Today, secure gear shifting is possible with a simple operation. The starting point of this was the development of POSITRON, a rear derailleur equipped with an index system called POSITRON SYSTEM. POSITRON, which was adopted in bicycles around the world, lowered the inhibitions of general users about using rear derailleurs and its concept was later rolled out to racing components. In this way, it played a leading part in Shimano bringing about a revolution in shifting systems.