| 摘要 |
Embodiments of a bicycle riding training system are disclosed. The system includes a crank assembly that is removable from the bicycle without disruption of the sprocket and chain. The invented system comprises coaxial shafts that rotate preferably together in a hub bearing assembly. The coaxial shafts preferably include an external shaft within the bearing retainer cups of a bicycle frame bottom hub assembly and an internal shaft that connects to the crank arms. The internal shaft preferably is made of two parts that connect at a midpoint within the external shaft using a bolt, screw or other connector. Removing the connector permits withdrawal of the internal shaft while leaving the external shaft and sprocket assembly intact. An additional feature of the connector in the internal shaft is that it may serve to expand or otherwise tighten the internal shaft inside the external shaft, and thereby fix the internal shaft to the external shaft. With the invented removable shaft system, the external shaft, sprocket and chain remain in place when the crank arms and pedals on the internal shaft, for training purposes.
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