Bike gear ratio calculator
Enter your chainrings and cassette and see every gear side by side: ratio, gear inches, development and the speed each one gives at your cadence. A typical 50/34 road setup with an 11-32 cassette spans roughly 7 to 32 mph at 90 rpm.
Lowest gear
34/32 · 7.6 mph
Highest gear
50/11 · 32.6 mph
Gear range: 428% at 90 rpm
| Gear | Ratio | Development | Gear inches | Speed at 90 rpm |
|---|---|---|---|---|
| 34/32 | 1.06 | 7.4 ft | 28 | 7.6 mph |
| 34/28 | 1.21 | 8.5 ft | 33 | 8.7 mph |
| 34/25 | 1.36 | 9.5 ft | 36 | 9.7 mph |
| 34/22 | 1.55 | 10.8 ft | 41 | 11.1 mph |
| 50/32 | 1.56 | 10.9 ft | 42 | 11.2 mph |
| 34/20 | 1.70 | 11.9 ft | 46 | 12.2 mph |
| 50/28 | 1.79 | 12.5 ft | 48 | 12.8 mph |
| 34/18 | 1.89 | 13.2 ft | 51 | 13.5 mph |
| 50/25 | 2.00 | 14.0 ft | 54 | 14.3 mph |
| 34/16 | 2.13 | 14.9 ft | 57 | 15.2 mph |
| 50/22 | 2.27 | 15.9 ft | 61 | 16.3 mph |
| 34/14 | 2.43 | 17.0 ft | 65 | 17.4 mph |
| 50/20 | 2.50 | 17.5 ft | 67 | 17.9 mph |
| 34/13 | 2.62 | 18.3 ft | 70 | 18.7 mph |
| 50/18 | 2.78 | 19.5 ft | 74 | 19.9 mph |
| 34/12 | 2.83 | 19.9 ft | 76 | 20.3 mph |
| 34/11 | 3.09 | 21.7 ft | 83 | 22.2 mph |
| 50/16 | 3.13 | 21.9 ft | 84 | 22.4 mph |
| 50/14 | 3.57 | 25.0 ft | 96 | 25.6 mph |
| 50/13 | 3.85 | 27.0 ft | 103 | 27.6 mph |
| 50/12 | 4.17 | 29.2 ft | 112 | 29.9 mph |
| 50/11 | 4.55 | 31.9 ft | 122 | 32.6 mph |
Development is calculated from the wheel circumference at typical pressure; your actual tire may differ by 1-2%. On 2x and 3x drivetrains, avoid the extreme combinations (big ring with big cog and the reverse): the chain runs at a steep angle and wears out faster.
How are gear ratios calculated?
The entire mathematics of a drivetrain fits into three formulas, all standard since Sheldon Brown's writing on gearing:
ratio = chainring teeth / cog teeth development = ratio x wheel circumference [m] gear inches = ratio x wheel diameter [inches] speed = development x cadence x 60/1000 [km/h]
All three conventions appear here because each has its constituency: development in metres dominates in Europe, gear inches in English-language literature, and the raw ratio is easiest for comparing drivetrains. Worked example: 50/14 on a 700x28C wheel (2,136 mm circumference) is a ratio of 3.57, 7.6 m of development and about 25 mph at 90 rpm. Wheel circumferences come from ETRTO tables for standard tire sizes, so expect a 1-2% difference from your specific tire and pressure.
Since pressure changes rolling circumference, set it in the tire pressure calculator before comparing drivetrains to a tenth of a mph. And if you want to know what it takes to actually hold those speeds, the cycling power calculator has the watts.
What is this calculator actually for?
The most common use is a cassette swap: you want an easier gear for climbing but need to know what it costs you at the top end. Enter both cassettes and compare the extremes. The second is choosing between 1x and 2x before buying a gravel bike, where the question is not range but the size of the jumps between gears. The third is checking your gearing before a mountain trip, which is the moment most riders discover their lowest gear is one or two cogs too hard.
Frequently asked questions
- What does gear ratio mean on a bike?
- It is the number of chainring teeth divided by the number of cog teeth. A 50 tooth chainring with a 25 tooth cog gives a ratio of 2.0, meaning the wheel turns twice for every turn of the cranks. Higher ratios mean more speed at the same cadence and more force at the pedals.
- What is the difference between gear inches and development?
- They are two units for the same thing. Development (metres) is how far the bike travels per crank revolution: ratio times wheel circumference. Gear inches is the older Anglo-American convention: ratio times wheel diameter in inches. A 50/25 gear on 700x28C is about 4.3 m of development, or about 53 gear inches.
- What is cross-chaining and why avoid it?
- Cross-chaining is riding the extreme combinations: biggest chainring with biggest cog, or smallest with smallest. The chain runs at a visible angle, which adds friction, wears the drivetrain faster and often rattles. On a 2x drivetrain you can usually find the same ratio on the other chainring with a straight chainline.
- What gear range do you need for climbing?
- For steep climbs you want a lowest gear near or below a 1.0 ratio: a 34 tooth chainring with a 34 tooth cog is exactly 1.0. Above 200 lb (90 kg) of rider weight, or on gradients above 10%, go lower still, for example 34/36 or a 1x setup with a 50 or 52 tooth cog. The calculator shows what speed that gear gives at a comfortable cadence.
- Is 1x enough for road riding?
- It depends on the terrain. A single chainring with a wide cassette (say 42 with 10-44) covers a similar range to a classic 2x, but the jumps between gears are larger, which makes holding an exact cadence harder on flat roads. For steady flat riding 2x is usually nicer; for mixed terrain and gravel the simplicity of 1x often wins.