Calculadora de Relacao de Marchas
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
relação = prato / catraca | desenv = relação × diam × π
About this calculator
This calculator determines bicycle gear ratios by dividing the number of teeth on the chainring by the number of teeth on the cassette. The result shows how many times the rear wheel turns per full pedal stroke. For example, a 50-tooth chainring with a 12-tooth cassette gives a ratio of 4.17, meaning the wheel spins 4.17 times per pedal revolution.
In addition to the ratio, the tool calculates the development in meters, which is the distance traveled per pedal stroke. Development is obtained by multiplying the ratio by the wheel circumference (wheel diameter × π). This helps cyclists compare gears practically, as it shows actual ground advance.
Use this calculator when adjusting your bike's drivetrain, whether for road, mountain, or urban riding. Road cyclists seek high ratios for speed; in MTB, low ratios make steep climbs easier. With the values, you can plan chainring or cassette changes to optimize performance.
Caution: theoretical development does not consider factors like rider weight, terrain slope, or tire resistance. The calculator assumes a perfectly round wheel with no slippage. Use results as a reference, but adjust based on your riding experience.
Frequently asked questions
What does a high or low gear ratio mean?
A high ratio (e.g., 4.17) means the bike travels further per pedal stroke, ideal for speed on descents or flat terrain. A low ratio (e.g., 1.5) requires less force, great for climbs.
How do I measure the wheel diameter correctly?
Measure the total diameter of the mounted tire, including rim and tire. Use a tape measure from the ground to the top of the wheel. Enter the value in inches or millimeters.
Can I use this calculator for fixed-gear bikes?
Yes, it works the same way. The ratio is fixed, so development is constant. It helps choose the ideal chainring and cog combination for your style.
What is the difference between ratio and development?
The ratio is a dimensionless number (chainring/cog). Development converts that ratio into distance traveled (meters per pedal stroke), considering wheel size.
Why is my actual development different from the calculated one?
Differences occur due to rider weight, tire pressure, terrain slope, and drivetrain efficiency. The calculation is theoretical; actual may vary.