Bicycle Gear Ratio Calculator

Calculate the gear ratio, gear inches, and potential speed for your bicycle based on your chainring, cassette, wheel size, and pedaling cadence. This calculator helps cyclists optimize their gearing setup for different riding conditions.

Why Use This Calculator?

• Understand how different gear combinations affect your cycling performance
• Plan gear changes for different terrain types
• Compare different gearing setups before making changes
• Calculate theoretical speeds at various cadences
• Optimize your bike’s gearing for your riding style

How to Use

1. Enter your bike’s specifications:

   • Front chainring teeth count
   • Rear cassette sprocket teeth count
   • Wheel size (diameter in inches)
   • Pedaling cadence (rpm)

2. The calculator will show you:

   • Gear ratio
   • Gear inches
   • Speed at your specified cadence
   • Development meters (distance traveled per pedal revolution)

Understanding Results

Gear Ratio

The gear ratio is the number of teeth on the front chainring divided by the number of teeth on the rear sprocket. A higher ratio means harder pedaling but potentially higher speed.

Gear Inches

Gear inches represent the equivalent diameter of a direct-drive wheel that would give the same mechanical advantage. Higher gear inches mean harder pedaling but more distance covered per revolution.

Speed Calculation

The calculator uses your cadence (pedaling speed) to estimate how fast you’ll go in each gear combination. This helps you choose appropriate gearing for your target speeds.

Common Use Cases

• Road Cycling: Optimize gearing for flat terrain and high speeds
• Mountain Biking: Find appropriate gear ratios for climbing and technical terrain
• Track Cycling: Calculate optimal fixed gear ratios
• Touring: Plan gearing for loaded touring and varied terrain

Tips for Choosing Gear Ratios

• For general riding, aim for a gear ratio range of 2:1 to 4:1
• Climbing typically requires ratios below 2:1
• High-speed riding may use ratios above 4:1
• Consider your fitness level and typical terrain
• Factor in your preferred cadence range

Technical Notes

• Calculations assume no tire deformation
• Actual speeds may vary due to factors like tire pressure and road conditions
• Gear inches calculation: (Chainring teeth × Wheel diameter) ÷ Sprocket teeth
• Speed calculation: (Gear inches × π × Cadence × 60) ÷ (12 × 5280) for mph

References

• Sheldon Brown’s Gear Calculator
• Park Tool’s Guide to Bicycle Gearing
• UCI Regulations for Racing Gear Ratios