| 摘要 |
A free cog wheel with a left handed thread (2) is screwed on the thread of a double threaded hub (I) having a left handed and a right handed thread.A free cog wheel with right handed thread (3) is screwed on the hub right handed thread. These wheels are connected by two chains (7,8) to two plates fixed on a pedal by double fixing (4). One of the two plates (5,6) may be replaced by multiple plates provided with Derailleur gears. One of the two free wheels may be replaced by free cog wheels having a Derailleur gear. USE - Enables rapid gear changing on pedal cycles.
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