Cyberbrick Gearbox G21 – 1:21 Reduction Gearbox

The CyberBrick Official Truck is a fantastic model, but I found the default 1:48 gear ratio a bit too slow. To improve speed and responsiveness, I modified the original reduction gearbox assembly and designed a custom 1:21 version: Gearbox G21.

This model is great for those who already own the CyberBrick 1:48 gear set but want something faster.

This gearbox uses only the standard 030 Micro DC Motor, the Motor Pinion, and the two 2 mm thick, 18 mm long metal rods from the original gearbox assembly. All other parts are 100% 3D-printed, with the housing retaining the same external dimensions as the original; ensuring perfect compatibility.

Precision?
Not quite as accurate or durable as the official nylon gears; but it gets the job done under light-load conditions.

Performance?
Absolutely suitable! Especially when printed in PETG and lubricated with some grease for smoother operation.

Update History

2025-08-31
The crown gear teeth were slightly short, so the model has been adjusted. In addition, all gears were refined to reduce elephant foot during printing, ensuring the 2 mm shaft fits smoothly through the gears.