| 摘要 |
A rotatable handgrip twistshifter (10) mountable coaxially about a bicycle handlebar (20) that abruptly or discontinuously increases the mechanical advantage when shifting a front derailleur from a smaller to a larger chainring. A control cable (86) is slidably connected to the handgrip (12) such that during rotation of the handgrip (12) to effect gear shifts from the middle to larger chainrings of a triple chainring crankshaft (40, 41, 42), the cable (86) is abruptly dropped toward the handgrip axis of rotation thereby increasing the mechanical advantage or leverage of the shifter (10). Alternatively, the control cable (86) is slidably connected to the pivot arm (114) of a front derailleur such that during rotation of the handgrip (12) the cable (86) is deflected away from the derailleur pivot axis (207), likewise, increasing the mechanical advantage of the derailleur. |
