Sprocket Bike Gears

Calculate gear ratios, speed, and gain ratio for any bike setup — offline, instantly.

Sprocket is the precise bicycle gear calculator built for cyclists who want to know exactly what their drivetrain is doing — before they ride.

Enter your front chainring teeth, rear cog teeth, cadence in RPM, and wheel size. Sprocket instantly computes gear ratio, gain ratio, gear inches, and speed in km/h or mph. Change any value and the results update live — no button to press.

Ten built-in cassette presets cover every riding style: 11-speed road, gravel, and endurance cassettes; 10-speed touring and racing; 12-speed MTB wide-range cassettes with cog counts from 9 to 12 speed. Add your own custom cassettes by entering the full cog sequence.

Save bike setups with a name, chainring, cassette, wheel size, and target cadence. Each saved setup shows the hardest and easiest gear at a glance — gear ratio, gear inches, and top speed for both extremes — so you can compare setups before swapping components.

Everything runs offline. No account, no ads, no network calls.

Features:

• Live gear ratio, gain ratio, gear inches, and speed (km/h or mph)
• Cadence stepper from 40 to 200 rpm in 5-rpm steps
• Six wheel size options: 700c, 650b/27.5", 26", 29", 24", 20"
• 10 seeded cassette presets with full cog-by-cog listings
• Custom cassette entry with comma-separated cog sizes
• 5 seeded bike setups: Road Racer, Gravel Adventure, Trail MTB, Sprint Track, Loaded Tourer
• Full offline — works anywhere, no connection required