Cassette Gear Range & Step Calculator
Analyse a drivetrain: total gear range percentage for 1× and 2× setups, the ratio and percentage jump between each cog, gear inches and development per gear, duplicated gears on a double, cadence-speed spread, and a comparison of common cassettes (11-28, 11-34, 10-50, 10-52).
How it works
Ratio = chainring ÷ cog; range = highest ratio ÷ lowest; step = next cog ÷ cog − 1; gear inches = ratio × wheel diameter (in); development (m) = ratio × π × diameter; speed = development × cadence × 60 ÷ 1,000
A drivetrain is judged by its range — how far apart the easiest and hardest gears are, quoted as a percentage — and by the size of the steps between them, which determines how much cadence changes per shift. Modern 1× systems reach 500% with a single ring and a 10-52 cassette but with 15–20% jumps; road doubles achieve similar range with 8–10% steps at the cost of front shifting and several duplicated combinations. Gear inches (the diameter of the equivalent penny-farthing wheel) and development (metres per pedal revolution) express each gear on an absolute scale, and multiplying by cadence gives speed, so a rider can check that the top gear does not spin out on descents and the bottom gear allows climbing at a sustainable cadence with the load they carry.
Worked example
A 50/34 double with an 11-32 cassette spans 50/11 to 34/32 — a 428% range, 121 down to 28 gear inches on 700×28c wheels — with steps of 8–17%. Of the 22 combinations about 19 are distinct. At 90 rpm the top gear gives 52 km/h and the bottom 12 km/h, plenty for a 12% climb with luggage.
Frequently asked questions
How much range do I need?
Flat commuting 250–300%; road riding with hills 350–450%; loaded touring and MTB 450–520%. If your lowest gear is under about 20 gear inches you can climb almost anything seated.
Why do 1× cassettes have bigger steps?
Twelve cogs must cover the whole range that a double covers with two rings, so each step is larger (13–20%). Riders on 1× accept a wider cadence band in exchange for simplicity and chain security.
Related calculators
Standard bicycle-mechanics formulas (spoke-length geometry, ETRTO circumferences, Sheldon Brown / Park Tool conventions). Measure your own components — rim ERD, hub dimensions and tyre size vary by make — and verify on the bike before cutting or ordering.