do you mean when switching from a 23t to a 27t? I don't believe so - after installing the new cassette I had my local shop basically do a little RD tweak when installing new shifter cables ...since then, I think I switched the chain out with a new one and basically matched the length to the original. I realize that could be creating a bit of stubbornness when shifting onto the 27t, but would that have a bearing on the jockey pulley clearance/B screw adjustment?