Compare bike gears before you buy or shift
Is 52/11 meaningfully harder than 50/12? Gear inches and development turn cassette choices into numbers you can compare.
Tools used in this guide
The job
Gearing is hard to feel from teeth counts alone. Two numbers fix that: gear inches (the diameter of an equivalent direct-drive wheel) and development (how far one crank turn rolls the bike).
From teeth to distance
Enter the chainring, the cog, and the wheel's outer diameter in mm — about 700 mm for a 700c road wheel with a ~23 mm tire. Speed at a cadence and the gain ratio (crank-length aware) come along too.
Worked example
52/11 on a 700 mm wheel: 130.3 gear-inches, 10.40 m per crank turn — at 90 rpm that is 56.1 km/h. The climbing end, 34/34, drops to 27.6 inches and 9.2 km/h at 70 rpm. Two gears that differ by one tooth differ by roughly that tooth's share of the ratio.
Scope
Chainring and cog 5–120 teeth each, wheel 200–1,000 mm, crank 100–200 mm, cadence 20–200 rpm. The wheel figure is the true outer diameter including the tire — measure it for precision; internal-hub and belt ratios are not included.