Gear Inch Calculator
RC Drivetrain Calculator By Warren Beauchamp     
Inches     Version 0.9
   Development in progress
  • To use this calculator, you'll need to measure the height (diameter) of your (loaded) rear tire,
  • Motor KV * Battery voltage = max motor RPM unloaded.
  • Loaded speed (actual use!) is generally around 70% of the max motor speed, but that will vary due to air resistance caused by by the rider size and riding position, and tire rolling resistance.
  • Each gear reduction stage adds friction to your design.
  • This calculator allows for three reduction stages. If your drivetrain has one or two stages, set the primary and secondary gears to 1 for the unneeded reduction stages in the calculator.
  • Higher overall reduction ratios give more torque at the wheel, but add complexity and can reduce reliability.


Drive tire diameter: Inches
Motor KV:
Battery Voltage: Volts
Percentage of speed when loaded: %
Motor Speed: RPM
Reduction1 - primary: Teeth
Reduction1 - secondary: Teeth
Reduction2 - primary: Teeth 
Reduction2 - secondary: Teeth
Reduction3 - primary: Teeth 
Reduction3 - secondary: Teeth
Speed at specified motor RPM =   29.438 MPH

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