Free calculator
Bike Gear Calculator
Map every gear on your bike — ratios, gear inches, meters of development, and speed at your cadence. Spot overlapping gears, measure total range, and check derailleur capacity before you buy a cassette.
Chainrings
Cassette
Wheel, crank & cadence
Rolling circumference ≈ 2111 mm (2.111 m).
Gear chart
Gear inches — darker cells are harder (faster) gears
| Ring \ Cog | 11 | 12 | 13 | 14 | 15 | 17 | 19 | 21 | 24 | 27 | 30 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 50 T | 120.3 | 110.2 | 101.8 | 94.5 | 88.2 | 77.8 | 69.6 | 63.0 | 55.1 | 49.0 | 44.1 |
| 34 T | 81.8 | 75.0 | 69.2 | 64.3 | 60.0 | 52.9 | 47.3 | 42.8 | 37.5 | 33.3 | 30.0 |
Gear progression
All combinations sorted easy → hard. Bars show relative gear inches.
Highlighted gears overlap within 3% — they feel nearly identical on the road.
Full gear table
| Gear | Ratio | Gear ″ | Dev. (m) | Gain | kph | Step |
|---|---|---|---|---|---|---|
| 34 × 30 | 1.13 | 30.0 | 2.39 | 2.21 | 12.9 | — |
| 34 × 27 | 1.26 | 33.3 | 2.66 | 2.46 | 14.4 | 11.1% |
| 34 × 24 | 1.42 | 37.5 | 2.99 | 2.77 | 16.2 | 12.5% |
| 34 × 21 | 1.62 | 42.8 | 3.42 | 3.16 | 18.5 | 14.3% |
| 50 × 30 | 1.67 | 44.1 | 3.52 | 3.26 | 19.0 | 2.9% |
| 34 × 19 | 1.79 | 47.3 | 3.78 | 3.50 | 20.4 | 7.4% |
| 50 × 27 | 1.85 | 49.0 | 3.91 | 3.62 | 21.1 | 3.5% |
| 34 × 17 | 2.00 | 52.9 | 4.22 | 3.91 | 22.8 | 8.0% |
| 50 × 24 | 2.08 | 55.1 | 4.40 | 4.07 | 23.8 | 4.2% |
| 34 × 15 | 2.27 | 60.0 | 4.79 | 4.43 | 25.8 | 8.8% |
| 50 × 21 | 2.38 | 63.0 | 5.03 | 4.65 | 27.1 | 5.0% |
| 34 × 14 | 2.43 | 64.3 | 5.13 | 4.74 | 27.7 | 2.0% |
| 34 × 13 | 2.62 | 69.2 | 5.52 | 5.11 | 29.8 | 7.7% |
| 50 × 19 | 2.63 | 69.6 | 5.56 | 5.14 | 30.0 | 0.6% |
| 34 × 12 | 2.83 | 75.0 | 5.98 | 5.53 | 32.3 | 7.7% |
| 50 × 17 | 2.94 | 77.8 | 6.21 | 5.75 | 33.5 | 3.8% |
| 34 × 11 | 3.09 | 81.8 | 6.53 | 6.04 | 35.2 | 5.1% |
| 50 × 15 | 3.33 | 88.2 | 7.04 | 6.51 | 38.0 | 7.8% |
| 50 × 14 | 3.57 | 94.5 | 7.54 | 6.98 | 40.7 | 7.1% |
| 50 × 13 | 3.85 | 101.8 | 8.12 | 7.51 | 43.8 | 7.7% |
| 50 × 12 | 4.17 | 110.2 | 8.80 | 8.14 | 47.5 | 8.3% |
| 50 × 11 | 4.55 | 120.3 | 9.60 | 8.88 | 51.8 | 9.1% |
Speeds at 90 RPM. Gain ratio accounts for crank length (172 mm).
Summary
301%
total gear range
More free tools
How it works
Gear ratio = chainring ÷ cog. Gear inches scale that by wheel diameter (penny-farthing heritage). Development is meters rolled per pedal turn. Gain ratio divides by crank length so different crank sizes stay comparable. Speed = development × cadence.
Inspired by classic tools like gear-calculator.com.
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