Originally Posted by
Jeff Neese
Read this:
All About Bicycle Chainline
There is nothing about "fit measurements" when you are talking about chainline. It's a spec, not a "preference".
Chainline determines everything else, from your wheel dish and cassette combination to your crankset and front derailleur. Get that wrong from the start and you will be fighting drivetrain issues. Staying within your preferred narrow gear range to compensate is hardly correct.
Chainline basically sets the measurements for the rest of the drivetrain. Get as close to that as you can, and build the rest of the drivetrain from there.
OP isn't BUILDING A BIKE!
The OP is changing a crank/BB and wants their chain to run as straight as possible for the rings/cogs they use the most.
I do exactly the same thing! I use the longest BB that the FDER will span.
Both my bikes are 3X9 that I use as a 1X9 about 98% the time on the middle ring.
Even then, we're talking about the thickness of about 1.5 cogs.