| 摘要 |
The bicycle comprises a chain set that includes the crank assembly, the rear derailleur and the chain, the crank comprising chain rings (1,2,3) of differing sizes. A sensor (17) monitors the position of the gear selection lever (13) and is linked to a command unit (18) that shifts the chain across the chain rings and the rear sprockets to affect gear selection. The selected gear is displayed on a display unit (19). The control and sensor units also monitor the position of the chain in relation to the chain rings and sprockets against the selected gear to ensure that no extremes of chain movement either across the chain rings of sprockets is affected. It also ensures that extreme chain positions are not utilized resulting in the chain being stretched and what is commonly known as a crossed chain, an example of which being a large chain ring and large sprocket combination. The controller will select an equivalent combination that results in the same gear.
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