| 摘要 |
An improved chain guide pulley or derailleur pulley for use with a bicycle rear derailleur system. The chain guide pulley has a guide sprocket portion and a bearing portion. The sprocket portion has, on a circular outer periphery, a plurality of teeth cut thereon. The teeth have dimensions so as to engage an endless drive chain and a cylindrical shaped inner peripheral surface defining thereby a bearing aperture. The bearing is dimensioned to be in an interfitting relationship with the guide sprocket and be attachable to the bicycle rear derailleur system. The teeth thickness dimension is not more than about three-fourths of a minimum distance between opposed pairs of roller link plates of the drive chain such that a less accurate alignment of the chain guide pulley with any one of the rear sprockets is required to effectively cause the drive chain to shift from any one of the sprockets to any other sprocket of the rear sprocket cluster. The chain guide pulley further has a number of circumferentially spaced-apart debris-clearing apertures. The apertures are located on a concentric between the bearing section and the circularly configured outer periphery. The debris-clearing apertures preferably have circular cross-sections. Materials selected from the group consisting of brass, bronze, aluminum and alloys thereof, titanium, iron and alloys thereof, nylon, teflon, plastic and fiberglass may be used in fabrication.
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