| 摘要 |
This invention refers to a bicycle double-traction system; which has a central gear toothed by both of its faces, the upper and the lower; and which rotates independently in a ball-mould mounted in the central axle of the bicycle handlebars; each gear actuate the other at the same time rotating in the axle, a chain gear actuates by means of a chain, a gear with pawl of the bicycle front wheel, its movement is transmitted by the chain, which is mounted in both gears.
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