When to use this calculator
Compare bicycle gearing through effective wheel-diameter gearing units. Uses rolling wheel diameter, which can differ from the nominal tyre designation.
Explore the pace, splits & race time calculators for other questions in this topic. For a related calculation, use the Cycling Cadence Speed Calculator: Estimate bicycle speed from cadence, gear ratio and wheel circumference.
PUTTING IT INTO PRACTICE
Bicycle Gear Inches: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Wheel rolling diameter (inches) | 27 |
| Front teeth (integer) | 50 |
| Rear teeth (integer) | 25 |
| Result | 54 gear inches |
- Check the input labels and enter the example values above.
- Apply the relationship: Gear inches = wheel diameter × front teeth/rear teeth.
- The result is 54 gear inches, rounded for display.
How to interpret your result
Uses rolling wheel diameter, which can differ from the nominal tyre designation.
Use matching distance units and decimal minutes. A constant-pace plan does not forecast how terrain, conditions or fatigue will affect a race. A split is a time over a chosen reference distance.
Frequently asked questions
How do I read a result of 5.5 minutes per kilometre?
It means 5 minutes 30 seconds per kilometre, because 0.5 of a minute is 30 seconds.
When is the bicycle gear inches calculator useful?
Compare bicycle gearing through effective wheel-diameter gearing units. Uses rolling wheel diameter, which can differ from the nominal tyre designation.
How do I use the bicycle gear inches calculator?
Enter wheel rolling diameter (inches), front teeth (integer), rear teeth (integer). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Gear inches = wheel diameter × front teeth/rear teeth.
What should I check before using the result?
Uses rolling wheel diameter, which can differ from the nominal tyre designation.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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