| 摘要 |
This invention concerns a sprocket gear for facilitating the derailing of the chain of a bicycle transmission and other prime movers. The sprocket gear includes at least two sprockets axially and concentrically positioned relative to one another. Each sprocket includes a perimeter, a front face, and a back face. Gear teeth project axially from at least a first perimeter segment of the front face and at least a second perimeter segment of the front face is free of gear teeth. Gear teeth project axially from the back face perimeter at the at least second segment of the front face. No gear teeth project from the back face perimeter at the at least first perimeter segment of the front face.
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