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Bicycle hub dynamo driver / generator test bench

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aquila

@aquila_141816

This is a device to test bicycle hub dynamos/generators and its respective electrical loads.

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Updated at source: Jun 17, 2026

Model information

Source: Printables
Category: Mechanical Parts
License: Creative Commons — Attribution — Share Alike

Details Files (15)Makes & comments (Makes: 0) (Comments: 0)Remixes (0)Collections (5)

This is a device to test bicycle hub dynamos/generators and its respective electrical loads. This way you can test bicycle lights and phone chargers while respecting the real-life characteristics of the dynamo.

Update:

Fixed a bug
Added a version with a larger generator pulley

Hardware required:

DC motor (when using a smaller one, use one with attached gearbox, something like 5:1 to 10:1)
Bicycle hub dynamo
GT2 closed loop belt with 2mm pitch, 400 mm total length, 6 mm width
M5x10mm bolt + nut for the motor sled
2x M2x10mm bolt + nuts to attach the pulley to the hub
2x M3x10mm bolt + nuts to attach the small pulley to the motor.
Lead weights to increase the moment of inertia of the dynamo
Rubber band to attach the motor to the holder

Customizing the Freecad file:

Change VarSet -> motor_diameter to fit your motor
Set VarSet -> hub_number_spokes to 32 or 36 according to your hub
Change VarSet -> pulley_generator_spokehole_dist to the distance of the spokeholes to the center of the hub
Change VarSet -> pulley_generator_inner_big_diameter and pulley_generator_inner_small_diameter according to your hub dynamo
change VarSet -> motor_transmission_offset to change the distance motor face - side clamp, or:
- measure the "distance motor face - pulley inside face" and add 23 mm to get the motor_transmission_offset