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Bicycle Gear Ratio Calculator
Gear ratio, gear inches and development for a chainring and sprocket combination.
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Gear ratio
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Gear ratio, gear inches and development for a chainring and sprocket combination.
Bicycle Gear Ratio Estimator
Enter your numbers below for an instant estimate.
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💡 Tip: Ratio = chainring teeth / cog teeth; gear inches = ratio x wheel diameter.
How It Works
Key concepts behind this calculator
1
Enter Values
Fill in each field with your own numbers.
2
Calculate
Results update as you change the inputs.
3
Review
Read the breakdown and the explanation.
4
Adjust
Change values to compare scenarios.
Quick Reference Guide
Bicycle Quick Guide
Typical values for reference.
| Chainring | Cog | Wheel in | Gear ratio |
|---|---|---|---|
| 34 | 28 | 27 | 1.21 : 1 |
| 50 | 16 | 27 | 3.13 : 1 |
| 50 | 11 | 27 | 4.55 : 1 |
| 53 | 11 | 27 | 4.82 : 1 |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Common Questions
Bicycle Gear Ratio Calculator FAQ
Answers to common questions about this calculator.
Chainring teeth divided by cog teeth.
Ratio times wheel diameter in inches.
Ratio = chainring teeth / cog teeth; gear inches = ratio x wheel diameter.
It is an estimate based on the inputs you enter. Check real quotes, labels or official guidance for important decisions.