🚴 Bike Speed Calculator
Calculate road speed based on cadence, wheel size, and drivetrain gearing to plan pacing, gear selection, or indoor trainer targets.
Typical endurance cadence 85–95 rpm; sprints exceed 110 rpm.
700c road ≈ 700 mm; 29er MTB ≈ 735 mm.
Optional: used to estimate climbing power demand.
Speed
34.9 km/h
21.7 mph
Wheel & cadence
Wheel rpm 264.7 • Cadence 90.0
Gear ratio 50:17
Gear metrics
Gear inches 81.1 • Development 6.47 m/rev
| Scenario | Result | Notes |
|---|---|---|
| Cadence change ±10 rpm | 38.8 km/h • 31.0 km/h | Shows effect of high vs low cadence with same gear |
| Swap to easier gear (+2 rear teeth) | 31.3 km/h | Speed drops but cadence stays constant on climbs |
| Swap to harder gear (-2 rear teeth) | 39.6 km/h | Higher speed at same cadence for descents or sprints |
How to Use This Calculator
Enter cadence and wheel size
Cadence from head unit or trainer; wheel size from tire specs.
Input current gear teeth
Front chainring and rear sprocket teeth determine drive ratio.
Review speed output
Use km/h or mph values to plan pacing and gear selection.
Adjust gradient
Optional: estimate power demands on climbs for the given cadence and gear.
Formula
Speed (km/h) = Cadence × (Front ÷ Rear) × Wheel Circumference × 60 ÷ 1000
Wheel Circumference = π × Wheel Diameter (in meters).
Estimated Power ≈ Total Mass × g × Speed (m/s) × Gradient + Rolling Resistance.
Handy conversions: 1 gear inch ≈ 0.08 km per crank revolution • Development (meters) × cadence (rpm) ÷ 1000 × 60 = speed in km/h.
Cycling Strategy Tips
Maintain a cadence that suits your physiology. Use this calculator to learn how gear changes impact speed so you can shift efficiently in races or group rides.
Pacing strategies
- On climbs, downshift to maintain cadence and reduce muscular fatigue.
- On descents, shift to harder gears to avoid spinning out above 110 rpm.
- For time trials, aim for a steady cadence (90–100 rpm) aligned with FTP power.
Indoor training
- Match trainer speed targets to outdoor gearing combos for race simulations.
- Monitor cadence to avoid grinding low rpm that can stress joints.
Frequently Asked Questions
Why does wheel diameter matter?
Larger wheels cover more ground per revolution, increasing speed at the same cadence.
How accurate is the power estimate?
It’s a rough calculation; actual power depends on wind, rolling resistance, drivetrain efficiency, and rider weight.
Can I simulate different cassettes?
Yes—change rear teeth values to compare cassette options for various terrain.
Does tire width affect results?
Wider tires slightly increase diameter; adjust the wheel input accordingly for precise results.
What about e-bikes with assist?
Use this calculator to monitor cadence and speed, then factor in motor assist separately for power/effort analysis.