Use our free Bike Gear Calculator to analyze your cycling drivetrain. Quickly determine your gear ratio, gear inches, rollout distance, and estimated speed based on chainring and sprocket teeth, wheel circumference, and cadence. Perfect for road cyclists, mountain bikers, and commuters looking to optimize performance and efficiency.
Formula:
The primary calculation is the Gear Ratio, which is simply:
Gear Ratio = (Chainring Teeth) ÷ (Sprocket Teeth)
Other key metrics derived from this:
- Gear Inches =
Gear Ratio × Effective Wheel Diameter (in inches) - Rollout (meters) =
Gear Ratio × Wheel Circumference (in meters) - Speed =
(Rollout (meters) × Cadence (RPM) × 60 minutes) ÷ 1000 (to convert meters to kilometers)
Where:
- Chainring Teeth: Number of teeth on the front chainring.
- Sprocket Teeth: Number of teeth on the rear cassette sprocket.
- Wheel Circumference: The outer circumference of your wheel including the tire (e.g., in millimeters).
- Cadence: Your typical pedaling revolutions per minute (RPM).