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Bike Gear Calculator.

Calculate gear ratio, gear inches, and development from tooth counts and wheel diameter.

On-device calculationNo signup
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Set your values

Results update as you type.

Gear ratio: 2

Gear ratio

0.000000
Gear inches: 54

Gear inches

0.000000
Development (m): 4.309008

Development (m)

0.000000

Results update automatically as you type.

Use Cases

Compare gear setups

Use the calculator to compare different chainring and sprocket combinations to find the ideal gear for your riding style, terrain, and fitness level.

Example: Compare a 50/11 vs 50/12 to see the difference in gear inches.

Plan for climbs or sprints

Determine the gear ratio needed for steep climbs or fast descents by adjusting the teeth counts and wheel diameter to match your bike.

Example: Find a low gear for a mountain climb with a 34/32 combination.

Frequently Asked Questions

What is gear ratio in cycling?
Gear ratio is the number of teeth on the front chainring divided by the number of teeth on the rear sprocket. It indicates how many times the rear wheel turns for each pedal revolution. A higher ratio means harder pedaling but more speed.
What are gear inches?
Gear inches represent the effective diameter of the wheel in inches, calculated by multiplying the gear ratio by the wheel diameter. It's a standard way to compare gear setups across different wheel sizes.
What is development in cycling?
Development is the distance traveled per pedal revolution, usually in meters. It's calculated by multiplying gear inches by π (3.14159) and converting to meters. It helps you understand how far you move with each crank turn.

Tips & Common Mistakes

Tips

  • Ensure you enter the correct number of teeth on your chainring and sprocket; a miscount can lead to inaccurate results.
  • Measure your wheel diameter accurately, including the tire, for precise gear inches and development.
  • Use the gear ratio to understand the mechanical advantage; higher ratios require more force but yield more speed.
  • Compare multiple setups to find the sweet spot between cadence and speed for your riding conditions.

Common Mistakes to Avoid

  • Entering the wheel diameter in centimeters instead of inches, which will skew the gear inches and development results.
  • Using the number of teeth from the wrong component, such as the crank arm instead of the chainring.
  • Forgetting to include the tire size when measuring wheel diameter, leading to underestimating gear inches.

Last updated: August 13, 2026