Gear Calculator Bike

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Reviewed by David Chen, CFA & Cycling Mechanics Specialist Fact-checked for accuracy on Gear Ratios and Physics.

Optimize your cycling performance by calculating the perfect gear ratios. This professional gear calculator bike tool helps you determine speed, cadence, and development with precision.

Gear Calculator Bike

Leave one field empty to solve for it (requires 3 values).

Calculated Result
0.00

gear calculator bike Formula

Speed (km/h) = [Cadence × (Chainring / Cog) × Circumference × 60] / 1,000,000

Source: Sheldon Brown Gear Theory | Shimano Technical Documentation

Variables:

  • Chainring: The number of teeth on the front gear attached to the pedals.
  • Rear Cog: The number of teeth on the rear cassette gear.
  • Cadence: How fast you pedal in Revolutions Per Minute (RPM).
  • Wheel Circumference: The distance the wheel travels in one full rotation (mm).
  • Speed: The resulting ground speed in kilometers per hour.

What is gear calculator bike?

A gear calculator bike is an essential tool for cyclists, commuters, and professional racers to understand the relationship between their pedaling speed (cadence) and the actual velocity of the bicycle. By inputting the mechanical specifications of your drivetrain, you can optimize your effort for climbing, sprinting, or time-trialing.

Understanding gear ratios allows you to maintain an efficient “power band,” preventing muscle fatigue and ensuring that every watt of energy you produce is translated into effective motion.

How to Calculate gear calculator bike (Example)

  1. Identify your chainring size (e.g., 50T).
  2. Identify your rear cog size (e.g., 15T).
  3. Measure your wheel circumference (e.g., 700c tire is roughly 2100mm).
  4. Choose a target cadence (e.g., 90 RPM).
  5. Divide 50 by 15 to get the Gear Ratio (3.33).
  6. Multiply: 90 RPM × 3.33 × 2100mm × 60 / 1,000,000 = 37.76 km/h.

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Frequently Asked Questions (FAQ)

What is a good cadence for beginners?

Most beginners feel comfortable between 70-80 RPM, while experienced road cyclists aim for 85-95 RPM.

Does wheel size affect speed?

Yes. For a fixed gear ratio and cadence, a larger wheel covers more ground per revolution, resulting in higher speed.

Why calculate gear inches?

Gear inches provide a standardized way to compare gears across bikes with different wheel sizes.

What is cross-chaining?

Cross-chaining occurs when using extreme gear combinations (e.g., big chainring to biggest rear cog), which increases drivetrain wear.