| 摘要 |
A bicycle chainwheel plate is formed to reduce the weight of a chainwheel crank and to keep its stiffness at a high level. The chainwheel plate is coupled between a crank arm and at least one sprocket. In one embodiment, the crank arm is detachable from the chainwheel plate, while in the second embodiment, the crank arm is integrally formed with the chainwheel plate as a one-piece, unitary member. The crank arm is designed to accommodate a pedal at its free end and is centrally attached to the chainwheel plate at the other end. In the first embodiment, the chainwheel plate comprises a crank attachment portion having a centrally located crank attachment hole in which a crank arm can be fixed in a non-rotatable fashion, four connecting arm portions radially extending in four directions from the crank attachment portion, and chainwheel fixing portions bifurcating and extending outward from the tips of the arm portions. The outer sprocket is shaped as a ring and is fixedly coupled to the chainwheel fixing portions.
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