The Park website has a section on chainline maintenance. In it, they tell how to measure the chainline on your bike. But how do you find out what the chainline measurement should be? The bike I'm working on is a 2011 Rockhopper.
In other words, I can find out what the chainline actually measures, but how do I find out what it should measure? The measurement I'm talking about is the distance from the centerline of the bike to the center of the cassette. And the measurement from the center of the bike to the center of the midddle chainring. The bike I'm working on has a 3 ring system.
Actually, I think I just answered my own question. If I measure the chainline distance at the cassette, that measurement should match the chainline measurement at the chainrings. I can change the measement at the chainrings - by changing BB spindle length - to match the measurement at the cassette.