Optimize your cycling performance by understanding how your gears translate to road speed. This professional bicycle gear ratio speed calculator helps you plan your cadence and gear selection for any terrain.
Bicycle Gear Ratio Speed Calculator
Bicycle Gear Ratio Speed Calculator Formula:
Where Ratio = Chainring / Cassette. Constant is 1,000,000 for km/h and 1,609,344 for mph.
Formula Reference: Sheldon Brown Gear Theory →Variables:
- Chainring Teeth: The number of teeth on the front gear attached to the pedals.
- Cassette Teeth: The number of teeth on the rear cog attached to the wheel.
- Cadence: The revolutions per minute (RPM) at which you turn the pedals.
- Tire Circumference: The distance traveled by the tire in one full revolution (in mm).
Related Calculators:
- Bicycle Gear Inches Calculator
- Cycling Calorie Burn Estimator
- Optimal Cadence Power Calculator
- Bike Frame Size Chart Tool
What is a Bicycle Gear Ratio Speed Calculator?
A bicycle gear ratio speed calculator is a tool used by cyclists to determine the speed of a bike based on specific gear combinations and pedaling frequency. By knowing the size of your front chainring and rear cog, the calculator determines the “gear ratio,” which dictates how many times the rear wheel turns for every single pedal stroke.
This information is vital for competitive racing, touring, and bike commuting. It allows riders to select the most efficient gears for maintaining a target speed or climbing specific gradients without exhausting their muscles prematurely.
How to Calculate Bicycle Gear Ratio Speed (Example):
- Identify your Chainring (e.g., 50T) and Cog (e.g., 18T).
- Calculate Ratio: 50 / 18 = 2.78.
- Measure Circumference (e.g., 700x25c tire is approx. 2105mm).
- Set Cadence (e.g., 90 RPM).
- Apply formula: (90 × 2.78 × 2105 × 60) / 1,000,000 = 31.6 km/h.
Frequently Asked Questions (FAQ):
Is a higher gear ratio better for speed? A higher ratio (large front, small rear) allows for higher speeds but requires significantly more leg force to turn the pedals.
What is a good cadence for beginners? Most beginners feel comfortable between 70-80 RPM, while experienced cyclists often aim for 85-95 RPM for efficiency.
How do I find my tire circumference? You can check the sidewall of your tire for the size (e.g., 700x28c) and look up a standard table, or perform a “roll-out” test for precision.
Does wheel weight affect this calculation? No. This formula calculates theoretical speed based on mechanical geometry; weight affects acceleration and effort, not the ratio itself.