Abstract: Disclosed is a crank variable-speed gear device (100) wherein the gear ratio can be increased to 1.6:1 to 1.8:1 through a gear assembly and a latch assembly, and the gear ratio can also be changed to 1:1, if necessary, thereby providing an excellent transmission efficiency, facilitating the manipulation thereof, and making it possible to provide a compact and lightweight bicycle.

Abstract: Disclosed is a crank variable-speed gear device (100) wherein the gear ratio can be increased to 1.6:1 to 1.8:1 through a gear assembly and a latch assembly, and the gear ratio can also be changed to 1:1, if necessary, thereby providing an excellent transmission efficiency, facilitating the manipulation thereof, and making it possible to provide a compact and lightweight bicycle.

Abstract: Disclosed is an adjustable speed gear apparatus that is installed on the hub shaft of the rear wheel of a bicycle to increase the driving speed and moving distance of the bicycle by two or more times on the average by improving the internal structure thereof in such a way so as to strengthen the support force of a transmission gear and to increase the coupling force between components, and can make the bicycle compact and light by constituting the wheels and crank of the bicycle to be small in size.

Abstract: An accelerating system for improving the running speed of a bicycle including: a main hub housing, a hub bush engaged with the main hub housing and having a sun gear, a gear cover having latches and having fixed shafts for rotatably supporting planetary gears in a meshing engagement with the sun gear, a gear housing having a ring gear with a gear-type engaging portion positioned on the hub shaft such that the planetary gears engage with the ring gear, a locker threadedly engaged with the gear-type engaging member, a hollow cylindrical auxiliary hub housing having an inner stage portion for receiving an outer periphery surface of the gear housing, and an auxiliary hub housing cover having a gear latch portion for engaging with the latches of the gear cover such that the auxiliary hub housing cover only rotates in one direction.

Abstract: An accelerating system for improving the running speed of a bicycle including: a main hub housing, a hub bush engaged with the main hub housing and having a sun gear, a gear cover having latches and having fixed shafts for rotatably supporting planetary gears in a meshing engagement with the sun gear, a gear housing having a ring gear with a gear-type engaging portion positioned on the hub shaft such that the planetary gears engage with the ring gear, a locker threadedly engaged with the gear-type engaging member, a hollow cylindrical auxiliary hub housing having an inner stage portion for receiving an outer periphery surface of the gear housing, and an auxiliary hub housing cover having a gear latch portion for engaging with the latches of the gear cover such that the auxiliary hub housing cover only rotates in one direction.