Originally Posted by
fietsbob
Mechanically defining chain line: a line parallel to the center-line of the bike ..
in a triple crank the middle chain ring is on a line matching the center of the rear cog cluster..
a cog if an odd number or the gap between the 2 most centered cogs if an even number..
do what you have to do to make it so.
...
Originally Posted by
dsbrantjr
Never Fix A Running Piece.
If you are having issues, the first quote. If you are not having issue the second quote.
IMO, chain line can't be assessed from the measurement to the seat post center alone. You still need to extend that imaginary line back to the rear cluster and see where it hits the stack. Preferably near the center of it.