Originally Posted by
roadnsnh
The order of business is, assuming that the derailer hanger is not bent, or has been realigned, is limit screws, cable adjust, and b screew. See
http://www.sheldonbrown.com/derailer-adjustment.html . This site and the Park Tool site will give you all the information you need.
Leland Yee
Disagree in the case of an already installed/setup derailleur that has developed shifting trouble. During installation sure, limit screws and b tension screw, but once setup you shouldn't need to touch those. Changes in shifting performance afterwards are usually cable tension or bent hangers.