This bike speed calculator estimates cycling speed from wheel diameter, tire size, gear ratio, and cadence.
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Bike Speed Calculator
Calculate bike speed from gear ratio and cadence.
Calculator
About this calculator
Formula notes
Speed = π × (wheel diameter + 2 × tire size) × gear ratio × cadence, where gear ratio = chainring teeth / cog teeth.
Worked examples
- Example: a 622 mm wheel with 25 mm tire, 50/15 gearing, at 90 rpm is about 38.05 km/h.
- At 80 rpm with a 50/12 gear ratio on a standard 700c wheel, theoretical speed is above 40 km/h.
How to use it
- Enter wheel diameter and tire size.
- Enter chainring teeth, cog teeth, and cadence.
- Read the gear ratio, pedal distance, and estimated speed.
Frequently asked questions
What is cadence?
Cadence is the number of pedal revolutions per minute (rpm).
Does this account for rolling resistance or wind?
No. It calculates theoretical speed from gearing and cadence; real speed is lower because of wind, rolling resistance, and terrain.
Limits and interpretation
- The result is theoretical speed without wind, rolling resistance, gradient, or drivetrain losses.
- Tire diameter and cadence must be entered accurately for a useful estimate.