An accelerating system for improving the running speed of a bicycle of which a drive wheel is installed on a hub shaft extending between parts of a bicycle frame, in which a chain gear is mounted to a one side of the drive wheel and it is operatively connected to a drive chain gear mounted on a pedal of the bicycle via a chain extending there between, the improvement comprising:
- a main hub housing having a central opening for receiving an engaging member, a first protrusion for guiding the engaging member into the central opening, in which the first protrusion is formed along a circumferential surface of the central opening on a one side surface of the main hub housing, and a second protrusion formed along a circumferential surface of the central opening on the other side surface of the main hub housing at a position opposite to the first protrusion;
- a hub bush having a sun gear integrally formed along an outer circumferential surface at a one side thereof, the hub bush being in meshing engagement with the second protrusion of the main hub housing, in which a plurality of ball bearings may be installed onto the outer circumferential surface of the hub bush;
- a ball guide bush being slideably mounted onto an outer surface of the hub bush;
- a gear cover for increasing the rotational speeds of the sun gear and the main hub housing to the n-fold speed, where n is a positive integer between 2 and 4, the gear cover being engaged with the ball guide bush, the gear cover having a plurality of latches for guiding the rotation in one direction which are formed at a one side of an outer circumferential surface thereof, and a latch spring for supporting the latches which may be mounted onto the outer circumferential surface of the gear cover, the gear cover including a plurality of fixed shafts for rotatably supporting a plurality of planetary gears to be in meshing engagement with the sun gear with the aid of a plurality of bearings, in which the fixed shafts are formed at a one side of the gear cover;
- a gear housing having a ring gear formed at an inner circumferential surface of a one side thereof, and a gear-type engaging portion formed at an inner circumferential surface of a central opening of the gear housing, in which the planetary gears of the gear cover may be in meshing engagement with the ring gear of the gear housing, and in which the gear housing may be supported on the main hub housing due to operation of the engaging portion;
- a locker having a female thread formed at an inner circumferential surface thereof, a plurality of engaging protrusions formed at an outer circumferential surface of a one side of the locker, and an insertion guiding portion formed at the other side of the locker, in which the female thread may be threadedly engaged with the engaging member provided onto the main hub housing, in which the engaging protrusions may be in meshing engagement with the engaging portions of the gear housing, and in which the insertion guiding portion may be inserted into the hub bush together with a bush ring;
- a hollow cylindrical auxiliary hub housing having an inner stage portion for receiving an outer periphery surface of the gear housing;
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- an auxiliary hub housing cover having a gear latch portion formed at an inner circumferential surface thereof, in which the latches of the gear cover may be in meshing engagement with the gear latch portion in a manner that they can rotate in a one direction along the gear latch portion.