Abstract: A mechanical mechanism is incorporated with two slotted discs -27- and -25- with two levers -14- and -16- which are inserted in the slots separating discs -27- and -25- to the length of the tips of levers -14- and -16-. Shifting the levers through the movement of activating shaft -2- which in turn moves impeller -7- creating, under the power of the coaster sprocket drive, a variation of speeds, though applied pressure. Stationary disc -27- being integrated with the bicycle retaining cylinder and floating disc -25- being free of the retaining cylinder will now be compelled only by the revolution of speed transmitted by the coaster sprocket drive. the structure and components of this invention are totally enclosed, minimizing difficulties in operation as one may shift into different speeds without flaws.