Drivetrain and gearing
Ratios, rollout, chain length and cassette range.
- Bicycle Gear Ratio CalculatorDivide chainring teeth by cog teeth. A 52×11 is about 4.72; a 36×34 is about 1.05. Lower is easier to spin uphill. The pair pages below run every tooth on a catalogued chainring against every cog on a catalogued cassette.
- Gear Inches and Roll-out CalculatorGear inches multiply the ratio by the wheel diameter. Roll-out is the metres the bike travels in one crank revolution — the number that tells you whether 52×11 on a 700×28c is actually a fast gear.
- Optimal Chain Length CalculatorA new chain is sized on the big-big combination, then you never ride big-big. This uses the standard link formula and rounds up to an even number so a quick link can close it.
- Derailleur Capacity CalculatorCapacity is how much slack the cage must swallow between big-big and small-small. A 1× setup uses the same tooth count for both chainring fields.
- Cadence to Speed CalculatorSpeed is cadence times how far one crank revolution takes you. Hold 90 rpm and change the cog if you want a different speed without changing fitness.
- Cassette Range CalculatorRange is a property of the cassette alone. It says nothing about whether your chainring makes the easiest gear actually easy.
- Fixie Skid Patch CalculatorA fixed gear skids on the same tyre spots unless the chainring and cog spread those spots out. More patches means the tyre lasts longer.