CALCULATOR 03
CHAINLINE
Do the two centres line up?
How far the chainring and the cog each sit from the frame centreline. The difference is your chainline offset.
日本語 →This calculator does not guess chainline from spindle length. That figure changes with every crank and shell combination, and guessing it misses by millimetres. Enter measured values or the manufacturer's published figures.
0 mm
Front minus rear / verdict: Aligned
An offset this small is unlikely to cause trouble in practice.
How to measure
Rear chainline = (over-locknut distance ÷ 2) − (distance from the outer locknut face to the centre of the cog). A 120mm track hub gives you 60mm as the reference.
Measure the front from the centreline of the seat tube to the centre of the chainring.