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RC gearing calculator

Calculate FDR, compare gearing and find a pinion for your next change.

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The initial values are an example, not a recommendation. Enter your car’s values.

Current setup
Proposed setup

The internal ratio is the reduction between the spur and the wheels. Check your manual; use 1 only if there is no further reduction.

Comparison

Find a pinion

Enter a target FDR. The proposed spur and internal ratio are used.

Compensate for a tyre change

Approximately preserve current rollout using the proposed spur, internal ratio and tyres.