Bike Gear Calculator
Calculate gear ratios, gear inches, development, and speed at various cadences for cycling. Perfect for choosing the right gearing for different terrain and optimizing your bike setup.
What is gear ratio in cycling?
Gear ratio is the number of chainring teeth divided by cassette cog teeth. Higher ratios (like 4.0) are "harder" gears for speed on flats, while lower ratios (like 2.0) are "easier" gears for climbing. A 50/12 combination gives 4.17 ratio, while 34/28 gives 1.21 ratio.
What are gear inches?
Gear inches represent the equivalent wheel diameter of a direct-drive bicycle with that gear ratio. Higher gear inches mean harder gears. Calculated as gear ratio × wheel diameter. Road bikes typically use 70-120 gear inches, while mountain bikes use 20-80 gear inches for climbing.
What is development in cycling?
Development is the distance traveled per pedal revolution in meters. Higher development means you travel farther with each pedal stroke but requires more effort. A road bike might have 8-9m development in high gear, while a climbing gear might be 3-4m.
What cadence should I aim for?
Most cyclists aim for 80-100 RPM on flats for efficiency. Climbing cadence drops to 60-80 RPM. Professional cyclists often maintain 90-100 RPM. Lower cadence (60-70) uses more leg strength, while higher cadence (100+) requires better cardiovascular fitness. Find what feels sustainable for you.
How do I choose the right gear ratio?
Choose based on terrain and fitness. For flat roads: 3.5-4.5 ratio. For rolling hills: 2.5-3.5 ratio. For steep climbing: 1.5-2.5 ratio. Compact road cranks (50/34) with 11-28 cassette provide 1.2-4.5 ratio range, suitable for most riding.