What this calculator does
Bike chain length works out chain length in links for a bike from chainstay length and the largest chainring and cog. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
The inputs explained
| Field | What to enter |
|---|---|
| Chainstay length (center-to-center) (in) | A number, measured in in. Starts at 17. |
| Largest chainring teeth | A number. Starts at 42. |
| Largest rear cog teeth | A number. Starts at 32. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with chainstay length (center-to-center)
Every other input is held at the calculator’s starting values while chainstay length (center-to-center) varies. Select any row to load that scenario into the calculator.