Shimano started the development of automatic shifting mechanisms based on a combination of an internal geared hub and a derailleur, and it released AUTOMATIC 5, which incorporated an automatic 2-speed internal geared hub with an automechanism inside a 5-speed free derailleur, in 1968 and AUTOMATIC II, featuring a further enhanced automatic shifting mechanism in 1969. At that time, automatic mechanism meant an automatic shifting system using centrifugal force, in which when the bicycle slowed down, it switched to a lower gear and when it picked up speed, it switched to a higher gear. Offering the advantage that the rider could start pedaling easily since the bicycle was in a low gear when stopped, which prevented the bicycle from tottering, the automatic gear systems were widely used for sports bikes and small-wheeled bicycles, as well as bicycles for women. However, since there was a major gap between the timing for shifting ideal for riders and the automatic shifting that used centrifugal force, they were not well received by the market.