Gear Ratio Calculator
Compare drivetrains, visualize cadence and speed across gears.
- Current328%
2× 50/34 · 11–32 11sp
- Range
- 328%
- Easiest
- 34×32 (1.06)
- Hardest
- 50×11 (4.55)
- Top @ 90 rpm
- 51.7 km/h
- Avg jump
- 11.3%
- Biggest jump
- 14.3% 14→16
Bike setup
How this works
Five values are computed for every chainring × cog combination. All math is pure and lives in src/lib/calculations/gear-ratio.ts; the full methodology with citations is on GitHub.
- Ratio
front_teeth / rear_teeth— unitless, the pure mechanical ratio.- Gain ratio
(wheel_radius / crank_length) × ratio— Sheldon Brown's metric. Comparable across crank lengths and wheel sizes.- Development
wheel_circumference × ratio— meters per pedal revolution.- Gear inches
(wheel_diameter_in) × ratio— historical metric; equivalent direct-drive wheel diameter.- Speed at cadence
development × cadence × 60 / 1000— km/h at your reference cadence.
Wheel circumferences come from a measured rollout table cross-referenced with Sheldon Brown, Continental, and Schwalbe technical data. Cassette cog progressions come from a curated database of manufacturer specs (Shimano, SRAM, Linkglide) with log-spaced interpolation as a fallback for unknown combinations.
Cross-chain combinations (big ring + 2 largest cogs, small ring + 2 smallest cogs on a 2x; outer rings only on 3x) are marked in the table and faded in the chart. The middle ring on a 3x is always considered usable.
View full methodology on GitHub →
Sources: Sheldon Brown, ISO 5775, Continental and Schwalbe technical references, Shimano and SRAM product specs.