The area that I've circled is the critical one for adjusting your b screw. You don't want the jockey wheel to foul on the cog here. So by screwing the b in, you increase the distance from the jockey to the cog here. The optimal distance is about 1/4' or less, but I think with this drivetrain, there is more leeway than with say, DuraAce or Sram Red. (no disrespect intended - this is a good, serviceable groupset.
