Bike Gear Calculator
Find your bike’s gear inches, development distance, and estimated speed for any chainring, cog, wheel size, and pedaling cadence.
What are gear inches?
Gear inches are a standard way to compare bicycle gearing across different bikes, wheel sizes, and drivetrains. A higher number means a harder gear that covers more ground per pedal stroke but requires more effort; a lower number means an easier gear for climbing.
How this calculator works
Gear Inches = (Chainring Teeth ÷ Cog Teeth) × Wheel Diameter (in inches, including the tire). This calculator also converts that into ‘development’ — the actual distance in meters your bike travels for one full pedal revolution — and estimates your speed at the cadence (pedal RPM) you enter, using Speed = Development × Cadence.
Wheel diameter varies slightly by tire width and brand, so the wheel size options here use commonly accepted approximate diameters for each format.
This tool is for general reference and gear-comparison purposes; actual rollout can vary slightly with tire pressure, load, and terrain.