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28 to 30: Limit screws?

poptart242poptart242 Posts: 495
edited April 2019 in Workshop
Hello, quick question here.

Just picked up a new cassette - R8000 11-30. About to fit it to replace an 11-28 R8000, to be used on a 9100 groupset.

Given it's only a couple of teeth, will I need to adjust anything? The chain is long enough so that's fine, and the RD is rated by Shimano to 30t. Will I need to play with the limit screws or is it for all intents and purposes a straight swap?

Posts

  • keef66keef66 Posts: 13,123
    Should be a straight swap. No need to touch the limit screws, the sprockets will be in the same place laterally.

    You might need to screw in the B screw a bit if it was previously adjusted so the upper jockey wheel just cleared the 28t sprocket.
  • poptart242poptart242 Posts: 495
    keef66 wrote:
    You might need to screw in the B screw

    Ah, that's the one I was thinking of! Perfect, thanks very much.
  • keef66keef66 Posts: 13,123
    I just went from a 27t to a 32t max sprocket which was quite a jump. Limit screws untouched but I did need to lengthen the chain a couple of links and screw the B screw in a few turns.

    Oddly I also had to adjust the indexing via the barrel adjuster on the rear mech to get the shifting spot on. Still no idea why; makes no sense to me. It's all shifting sweetly now though.
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