| 摘要 |
PURPOSE: A power transmission device for chainless bicycles is provided to make efficient drive by maximizing the numbers of transmission shifts. CONSTITUTION: A power transmission device for chainless bicycles comprises a power transmission axis(300) and a speed change part. The power transmission axis transfers the driving force of a pedal axis(100) to the rear wheel by using a first bevel gear. The speed change part comprises a stationary gear group(210), a hollow axis of changing speed(220), an idle gear group(230), a shift lock member(240), and a second bevel gear(280). The stationary gear group comprises more than two stationary gears having different diameters. The stationary gears are integrally formed on a pedal axis or an output shaft rotating the rear wheel. The axis of changing speed is contiguous to the pedal axis or the output shaft. The shift lock member is installed in the axis of changing speed and selectively clinches one from idle gears. The second bevel gear is meshed with the first bevel gear of the power transmission axis.
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