| 摘要 |
An improved chain control unit for a bicycle of the type having a pair of crank arms rotatably mounted at their rear ends on a mount secured to the frame of the bicycle behind the rear wheel thereof. Thus, pedals on the front ends of the crank arms are driven up and down by upward and downward movements of the legs. The chain control unit includes a follower for each crank arm, respectively, each follower operating to change the angular relationship between a pair of adjacent stretches of the chain in a manner to progressively increase the angular travel of a sprocket at the hub of the rear wheel in response to uniform angular, downward travel of the corresponding crank arm to thereby provide for optimum torque applied to the rear wheel. Several embodiments of the chain control unit are disclosed including one having an overriding feature operated by a manually actuated control device carried on the handlebar or other suitable location.
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