CalculatorsBicycle Gear Ratio Calculator
SRAM XX1 Eagle 32 gearing with Shimano Deore XT M8100 10-51T
Ultra-lightweight mountain bike ring, standard for steep climbs and technical trails. Smooth-shifting Hyperglide+ MTB cassette with a 510% gear range.
Easiest 0.62, hardest 3.20
The easiest gear (32 / 51) gives a ratio of 0.62, and the hardest (32 / 10) gives 3.20.
This is a winch gear. You will spin out on flat tarmac before the hill runs out. The spread from 0.62 to 3.20 is wide, so the cassette is doing the work of a much bigger chainring jump.
SRAM XX1 Eagle is a 1x mtb ring (BCD Direct Mount, 12 -speed) on a 12-speed Shimano cassette with a MicroSpline freehub. Both parts are catalogued as MTB, and the cassette speed sits on the chainring’s compatible-speed list.
Every chainring tooth against every cog
| Chainring | 10 | 12 | 14 | 16 | 18 | 21 | 24 | 28 | 33 | 39 | 45 | 51 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 32 | 3.20 Hardest | 2.66 | 2.28 | 2.00 | 1.77 | 1.52 | 1.33 | 1.14 | 0.96 | 0.82 | 0.71 | 0.62 Easiest |
Inputs
Results
- Gear ratio
- 3.20
How the number is made
Ratio = chainring ÷ cog. Published figures are truncated to two decimal places, so 36 ÷ 34 is shown as 1.05 and 52 ÷ 11 as 4.72. The live form uses the same truncation.
Ratio ignores wheel size. Gear inches and rollout add the tyre.
- Gear ratio. Truncated to two decimal places.
How pair pages are chosen
A chainring is paired with a cassette only when the cassette speed is in the chainring’s compatible-speed list. A track ring and a 12-speed cassette are not given a URL.
Related calculators
- Gear Inches and Roll-out Calculator
Same teeth, different development once the wheel size is in the sum.
- Cadence to Speed Calculator
Turns this ratio into km/h at the cadence you actually hold.
- Cassette Range Calculator
The percent range is the cassette alone, before a chainring is chosen.
Questions
What is a climbing ratio?
Around 1.0 or below (for example 36÷34 or 34÷51) lets you spin a steep grade. Above 1.5, the easiest gear is already hard work.
Why truncate to 1.05 instead of rounding to 1.06?
36÷34 is 1.0588. This site truncates to two decimals so every pair page quotes the same published figure.
Does the chainring brand change the ratio?
No. Teeth do. Brand, speeds and freehub decide whether the pair can be built.
Related gear
- Replacement cassette
Match the freehub (HG, Micro Spline, XD, XDR) before the tooth count.
$40–$400
- Matching chain
Speed count of the chain has to match the cassette, not just the chainring brand.
$20–$80