Cycling Gear Ratio Calculator
Gear Ratio
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Gear Inches
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Development (meters per revolution)
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Speed at 90 RPM (km/h)
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Understanding Cycling Gear Ratios
Gear ratio is the number of chainring teeth divided by the number of rear cog teeth. A 50/17 combination gives a ratio of 2.94:1, meaning the rear wheel rotates 2.94 times per pedal revolution. Higher ratios are harder to pedal but go faster.
Gear inches convert the ratio to an equivalent wheel size: GI = ratio × wheel diameter (inches). This standardizes comparison across different wheel sizes. Development is the distance traveled per pedal revolution in meters.
Typical cadence ranges from 80-100 RPM for road cycling. This calculator shows your speed at 90 RPM to help compare gearing. Climbing gears have ratios below 1.0 (small chainring, large cog), while top-end gears may exceed 4.0.
Frequently Asked Questions
What is a good gear ratio for cycling?
It depends on terrain. Flat roads: 2.5-3.5 ratios. Climbing: 1.0-2.0. Time trials: 3.5-4.5. Most road bikes offer a range.
What are gear inches?
Gear inches = gear ratio × wheel diameter. It represents the equivalent diameter of a single-speed wheel giving the same mechanical advantage.
What cadence should I aim for?
80-100 RPM is efficient for road cycling. 60-80 RPM for climbing. Higher cadence is easier on joints; lower cadence requires more leg strength.
What is development in cycling?
Development is the distance traveled per pedal revolution. Calculated as gear ratio × wheel circumference. Useful for comparing gearing across setups.