Bicycle Gear Ratio + Gear Inches Calculator
Ratio = front teeth / rear teeth. Gear inches = ratio × wheel diameter (in).
Result
Gear ratio
3.57:1
94.6 gear inches · 7.55 m / pedal stroke.
- Front teeth50
- Rear teeth14
- Ratio3.571
- Wheel diameter26.5"
- Gear inches94.6
- Development7.55 m
- Speed @ 90 rpm40.8 km/h (25.3 mph)
Step-by-step
- Ratio = 50 / 14 = 3.571.
- Gear inches = ratio × wheel diameter = 3.571 × 26.5 = 94.6.
- Speed = π × wheel diameter × ratio × cadence = 40.8 km/h.
How to use this calculator
- Read tooth count off chainring and cog.
- Pick wheel + tire size.
- Set cadence (90 is recreational standard).
- Compare gear inches between bikes for fair comparison.
About this calculator
Gear ratio is teeth in front divided by teeth in back. A 50t chainring and 14t cog = 3.57:1, meaning the wheel turns 3.57 times per pedal revolution. Gear inches (US road tradition) multiplies ratio by wheel diameter — useful because it normalizes across wheel sizes. A 50/14 on a 700x25 ≈ 95 gear inches; same ratio on a 26" MTB only ≈ 93. Pros at 90 rpm in 95 gear inches = ~32 mph.
Frequently asked
Compact 50/34 × 11-30 = 22.7 to 122 gear inches. A 1:1 lowest ratio (34×34) is the climbing standard now.
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