Gear inches to sprocket ratio
Type a value in gear in to get it in ratio instantly.
That's about the same as a cruising gear. At a steady 90 rpm that rolls about 30.16 km/h.
Convert the other way: ratio to gear in
What it means
How tall is that gear?
Wheel diameters include a typical tire for each size. A fat tire adds an inch or so, which is about 3% on the gear.
The math
How to convert gear in to ratio
Gear inches are wheel diameter × chainring ÷ sprocket. Development follows as gear inches × π × 0.0254 meters, and gain ratio as gear inches ÷ (2 × crank length). The figures below use the wheel selected above.
Example: 70 gear in = 2.6616 ratio.
The table below is for 700c road, 25 mm tire (26.3 in).
Every unit
Your gear in every unit
Tables
gear in to ratio conversion table
| gear in | ratio |
|---|---|
| 20 gear in | 0.760456 ratio |
| 30 gear in | 1.14068 ratio |
| 40 gear in | 1.52091 ratio |
| 50 gear in | 1.90114 ratio |
| 60 gear in | 2.28137 ratio |
| 70 gear in | 2.6616 ratio |
| 80 gear in | 3.04183 ratio |
| 90 gear in | 3.42205 ratio |
| 100 gear in | 3.80228 ratio |
| 110 gear in | 4.18251 ratio |
| 130 gear in | 4.94297 ratio |
ratio to gear in conversion table
| ratio | gear in |
|---|---|
| 20 ratio | 526 gear in |
| 30 ratio | 789 gear in |
| 40 ratio | 1,052 gear in |
| 50 ratio | 1,315 gear in |
| 60 ratio | 1,578 gear in |
| 70 ratio | 1,841 gear in |
| 80 ratio | 2,104 gear in |
| 90 ratio | 2,367 gear in |
| 100 ratio | 2,630 gear in |
| 110 ratio | 2,893 gear in |
| 130 ratio | 3,419 gear in |
Quick answers
Quick answers
- How many ratio is 1 gear in?
- 1 gear in is 0.0380228 ratio.
- How many ratio is 10 gear in?
- 10 gear in is 0.380228 ratio.
- How many ratio is 70 gear in?
- 70 gear in is 2.6616 ratio.
The units
About these units
Gear inches (gear in)
The classic measure: the penny-farthing wheel your gear is equivalent to.
Sprocket ratio (ratio)
Chainring teeth divided by sprocket teeth, before the wheel is counted.
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