Cycling cadence and gear speed
Multiply cadence by gear ratio and wheel circumference.
How this works
Theoretical speed in km/h = cadence in pedal revolutions/minute × (front chainring teeth/rear sprocket teeth) × wheel circumference in millimeters × 60/1,000,000. The gear ratio converts pedal revolutions to wheel revolutions; the final factor converts millimeters per minute to kilometers per hour.
Example
The illustration may use different inputs from the reproducible default inputs listed below.
The default calculation is 80 × (50/20) × 2,100 × 60/1,000,000 = 25.2 km/h. With all reset-default inputs, theoretical speed: 25.2 km/h.
- Pedal cadence (rpm)
- 80
- Front chainring teeth
- 50
- Rear sprocket teeth
- 20
- Wheel circumference (mm)
- 2100
- Theoretical speed
- 25.2 km/h
Scope and assumptions
Assumes engaged gearing, constant cadence and the entered rolling circumference, with no wheel slip or freewheeling. It does not model aerodynamic drag, gradients, tire deflection or rider power and is not a performance prediction.
OpenStax — algebra and proportional relationships
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