Bike Gear Ratio Calculator 2026
Instantly calculate your bicycle’s gear ratio, gear inches, development, and estimated speed. Perfect for tuning road, gravel, MTB, and commuting setups.
Drivetrain & Wheel Setup
Enter your chainring, cog, and wheel details to calculate gearing
The number of teeth on your front chainring. For 1x setups, enter the single chainring size.
The number of teeth on the selected rear cog or sprocket.
Your pedaling speed in Revolutions Per Minute. Leave at 0 or blank to skip speed calculation.
Gearing Results
Ratio, gear inches, development, and speed
Enter your drivetrain and wheel details above, then click Calculate Gear Ratio to see your results.
Typical Gear Inches by Discipline
General guidelines for gear inches across different cycling disciplines. Lower numbers are easier for climbing, while higher numbers are better for speed on flats.
| Discipline | Low Gear (Climbing) | Mid Gear (Flat) | High Gear (Descending) |
|---|---|---|---|
| Road Racing | 50″ β 55″ | 70″ β 85″ | 95″ β 120″+ |
| Gravel / Adventure | 20″ β 30″ | 45″ β 65″ | 75″ β 90″ |
| Mountain Bike (XC) | 20″ β 28″ | 35″ β 50″ | 60″ β 75″ |
| City / Commuter | 35″ β 45″ | 50″ β 70″ | 75″ β 85″ |
| Track / Fixie | 65″ β 75″ | 80″ β 90″ | 95″ β 110″ |
Bike Gearing FAQ
Everything you need to know about bicycle gear ratios, gear inches, development, and how to optimize your drivetrain for your riding style.
A bike gear ratio is the relationship between the number of teeth on the front chainring and the rear cog. It is calculated by dividing the number of chainring teeth by the number of cog teeth. For example, a 50-tooth chainring paired with a 25-tooth cog gives a gear ratio of 2:1, meaning the rear wheel turns twice for every single pedal revolution.
Gear inches is a traditional imperial measurement used to describe how ‘hard’ or ‘easy’ a gear is to pedal. It represents the equivalent diameter of a penny-farthing’s drive wheel. A higher gear inch number means a harder gear (more distance per pedal stroke), while a lower number means an easier gear (less distance, better for climbing).
Development is the metric equivalent of gear inches. It measures the exact distance the bicycle travels forward in meters for one complete revolution of the pedals. It is calculated by multiplying the gear ratio by the wheel’s circumference in meters. For example, a development of 5 meters means the bike moves 5 meters forward with every pedal stroke.
Wheel size significantly impacts your effective gearing. A larger wheel (like a 29″ MTB or 700c road wheel) covers more distance per revolution than a smaller wheel (like a 26″ or 20″ wheel). If you swap to a larger wheel without changing your chainring or cog, your gears will effectively become ‘harder’ (higher gear inches and development).
For steep road climbs, a gear ratio between 1.5 and 2.0 (e.g., 34T chainring / 28T cog) resulting in 25 to 40 gear inches is ideal. For mountain biking on technical, steep trails, riders often use ratios as low as 0.8 (e.g., 30T chainring / 36T cog) or even lower with a 1x drivetrain and a large 50T+ cassette cog, dropping below 20 gear inches.
To calculate speed, first find your development (meters per revolution) by multiplying your gear ratio by your wheel circumference in meters. Then, multiply the development by your cadence (RPM) and by 60 to get meters per hour. Finally, divide by 1,000 to convert to km/h. For mph, multiply the km/h result by 0.621371.