| 摘要 |
<p>An arm propulsion system for bicycles, that may be combined with the conventional foot propulsion, includes a sprocket wheel (5), that is coaxial with the pin (6) that connects the cranks (12), rotates in idle gear around said pin (6) and has on one side a radially toothed surface that gets engaged with one of two identical toothed surfaces present on the sides of a connection element (7) that is linked to the same rotation of the pin (6), making the sprocket wheel (5) linked or unlinked to the cranks' pin (6) according to the motion of said pin or of the sole said connection element (7).</p> |
