Calculate Your Bike Gearing
Enter your drivetrain and wheel values to calculate gear ratio, gear inches, rollout, and estimated speed at your preferred cadence.
What is a bicycle gear ratio?
A bicycle gear ratio tells you how many times the rear wheel turns for one full revolution of your pedals. The formula is simple: gear ratio = front chainring teeth ÷ rear cog teeth. If you ride a 50T chainring and a 14T cog, your ratio is 3.57:1, which means each pedal turn rotates the rear wheel about 3.57 times.
Higher ratios feel harder but go farther per pedal stroke. Lower ratios feel easier and are better for steep climbs, technical terrain, and long endurance riding.
How to use this bike gear calculator
- Front chainring teeth: Number of teeth on your front ring (or selected ring on a double/triple setup).
- Rear cog teeth: Number of teeth on the cassette sprocket you are currently using.
- Wheel diameter: Effective outside wheel diameter in inches (often near 27" for 700c road tires).
- Cadence: Your pedal rate in revolutions per minute (RPM), commonly 70–100 RPM.
Click Calculate and you’ll get:
- Gear ratio
- Gear inches
- Rollout (distance traveled per crank revolution)
- Estimated speed at your chosen cadence (km/h and mph)
Understanding the output
1) Gear Ratio
This is your mechanical leverage. A value like 4.00:1 is a high-speed gear. A value near 1.00:1 is much easier for climbing.
2) Gear Inches
Gear inches combine wheel size and drivetrain ratio: gear inches = gear ratio × wheel diameter. Higher numbers mean more distance per pedal turn. Road riders often use high gear inches on flats, while mountain riders prioritize lower numbers for steep ascents.
3) Rollout (Development)
Rollout is how far your bike travels with one full crank revolution. It is a practical metric when comparing setups between wheel sizes, disciplines, or bikes.
4) Estimated Speed
Speed depends on both gear and cadence. Two riders in the same gear can have very different speeds if one pedals at 75 RPM and the other at 95 RPM. This is useful when planning race pacing, training intervals, or commuting cadence targets.
Common gearing examples
Road bike
Typical setup: 50/34 crankset with 11–30 cassette. Riders use high ratios on descents and tailwinds, then shift to smaller chainrings or bigger cassette cogs for climbs.
Gravel bike
Gravel gearing often prioritizes versatility, such as 40T front with 10–44 cassette. This provides lower climbing gears while still preserving enough top-end for fast sectors.
Mountain bike
MTB riders usually run 1x drivetrains like 32T front and 10–51 rear. This creates excellent climbing ratios for steep trails and technical features.
Tips for selecting the right gearing
- Choose lower gearing for long climbs, loaded touring, and off-road traction control.
- Choose higher gearing if your routes are fast and mostly flat.
- Keep your preferred cadence in mind—many riders perform best around 80–95 RPM.
- If in doubt, pick gearing that makes climbing easier; fatigue compounds quickly on under-geared bikes.
FAQ
What wheel diameter should I use?
Use your effective outside diameter. A practical estimate is 27 inches for many 700c road tires and around 29 inches for many 29er MTB tires. For more precision, measure your actual wheel rollout on the ground.
Is gear ratio the same as cadence?
No. Gear ratio describes mechanical advantage. Cadence is how fast you pedal. Together, they determine speed.
Why compare gear inches and rollout?
They help you compare different bikes and wheel sizes more clearly than chainring/cog tooth counts alone. This is especially helpful when moving between road, gravel, and mountain platforms.
Whether you are tuning race gearing, planning a bikepacking setup, or simply trying to spin more efficiently, this bicycle gear ratio calculator is a quick way to make smarter drivetrain choices.