Bicycle Gear Ratio & Speed Calculator
Calculate bicycle gear ratio, gear inches, and speed at a given cadence.
Enter chainring size, rear cog, and wheel diameter.
Gear Ratio & Speed
Bicycle gear ratio determines how far you travel per pedal revolution.
Gear Ratio = Front Chainring Teeth / Rear Cog Teeth
Gear Inches = Gear Ratio × Wheel Diameter (inches)
Distance per Revolution = Gear Inches × π (inches)
Speed (mph) = (Gear Inches × π × Cadence × 60) / 63,360
When using metric (mm wheel diameter):
Speed (km/h) = Speed (mph) × 1.609
Common wheel diameters:
- 700c road (23mm tire): 26.3 inches (668 mm)
- 700c road (28mm tire): 26.7 inches (678 mm)
- 29er MTB: 29.0 inches (737 mm)
- 27.5" MTB: 27.5 inches (699 mm)
- 26" MTB: 26.0 inches (660 mm)
Typical cadence ranges:
- Recreational: 60–70 RPM
- Fitness: 75–85 RPM
- Road cycling: 85–95 RPM
- Racing: 95–110 RPM