Originally Posted by specialgreen

I'm not sure how to read Sheldon's page: it describes the chainline for each Shimano crankset, but doesn't mention which BB width was used in the measurement. I may be confused, but it seems like the chainline will be: half the width of the BB, minus whatever width is removed by the inward curve of the crankset. So I'd expect to read two separate numbers: the BB width (e.g. "68x126," which adds 63mm to chainline), and the offset of the particular crankset (e.g. "Shimano Supositorio MTB Triple has -14 mm offset to middle chainring"), and the combo would have 63 - 14 = 49 mm chainline.