How gear ratios work
Every time you push the pedals through one complete revolution, your chain pulls the rear sprocket around a number of times determined by the ratio between the front chainring and rear sprocket teeth. A 50-tooth chainring turning a 17-tooth sprocket rotates the rear wheel 2.94 times per pedal stroke.
Gear ratio alone doesn't tell the full story — wheel size matters. That's where development comes in. Development converts the ratio into actual distance travelled per pedal stroke, accounting for wheel circumference and tyre width.
Gear ratio = chainring teeth ÷ sprocket teeth
Development = gear ratio × wheel circumference (π × diameter)
Speed = development × cadence × 60 ÷ 1,000
Gain ratio = development ÷ (2π × crank length)
Common gear ratios at a glance
| Combo | Ratio | Use case | Speed @ 90rpm* |
|---|---|---|---|
| 34 / 32 | 1.06 | Steep climbing | ~15 km/h |
| 34 / 25 | 1.36 | Moderate climbing | ~19 km/h |
| 50 / 25 | 2.00 | Easy road riding | ~28 km/h |
| 50 / 17 | 2.94 | Moderate road / tempo | ~42 km/h |
| 50 / 11 | 4.55 | Fast flat / downhill | ~65 km/h |
| 48 / 17 | 2.82 | Fixed gear classic | ~40 km/h |
*700c wheel with 25mm tyre
Choosing gears for your riding style
Road bikes typically use compact (50/34) or standard (52/36) double chainrings with an 11-speed cassette. Compact gives more climbing range; standard gives closer steps for flat racing. Gravel bikes have shifted heavily to 1× with a 38–42t ring and wide-range 10–44t or 10–51t cassette. Mountain bikes use 1× with 28–36t rings and 10–51t cassettes to handle both steep climbs and fast descents.