Bicycle gearing and speed

Compare gear ratios, development and speed using wheel rollout and pedalling cadence.

Your inputs

The editable example is illustrative. Enter your own dimensions, operating data, prices, and fees. Results update as you edit.

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Complete the inputs to see your result.

Gear ratio = Chainring teeth/Rear cog teeth; Distance per crank revolution = Measured rollout×Gear ratio; Speed (km/h) = Distance per crank revolution (m) × Cadence (rpm) × 60/1000
Worked example: 50/25 = 2; 2.1 m × 2 = 4.2 m; 4.2 × 90 × 60/1000 = 22.68 km/h
Supported input limits: Chainring teeth: 1 ≤ x ≤ 500; Rear cog teeth: 1 ≤ x ≤ 500; Measured rollout: 1e-12 ≤ x ≤ 1000000000000; Measured wheel diameter: 1e-12 ≤ x ≤ 1000000000000; Cadence: 0 ≤ x ≤ 1000000000000; Optional gear combinations: 0–50

Bicycle speed follows measured rollout, gearing and cadence, without power or aerodynamic modeling.