Gear Inches
77.8
Gain Ratio
5.81
Speed
20.8 mph
Gear Inches
77.8
2.94 gear ratio
Gain Ratio
5.81
Development
6.2 m
Inputs
Result
50/17 = 2.94 ratio × 26.7" wheel = 78.5 gear inches.
Inputs
Result
30/50 = 0.60 ratio × 32.2" wheel = 19.3 gear inches.
Gear inches represent the effective wheel diameter multiplied by the gear ratio. A 50T chainring with a 17T cog on a 700c wheel gives about 79 gear inches, meaning each pedal revolution moves you as far as a 79-inch wheel rolling once.
| Gear Range | Gear Inches | Use Case |
|---|---|---|
| Easy climbing | 20–40 | Steep hills, loaded touring |
| General riding | 50–75 | Flat to rolling terrain |
| Fast cruising | 80–110+ | Flat roads, sprinting |
Gain ratio measures the distance traveled per unit of pedal arc distance. Unlike gear inches, it accounts for crank length, giving a more accurate comparison across different bikes.
Speed equals the development distance (wheel circumference times gear ratio) multiplied by cadence. At 90 RPM with a 50/17 on 700x25c, you travel about 21.5 mph.
For climbing, target gear inches under 40 (roughly a 1:1 ratio or lower). A 34T chainring with a 34T cassette cog gives about 27 gear inches on a road bike, good for steep 10%+ grades.
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Last Updated: Mar 20, 2026
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