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11-28 to 11-32 on short cage

rideforfunrideforfun Posts: 8
in Workshop
Bike : giant propel with shimano 105 5800 11-28 rear (short cage) and 34-50 front
According to manufacturer manuel rear derailleur can accommodate up 32 wich i did , with B screw tighten to the max i still have some rubbing. chain length with 28 seemed fine its also fine on the new 32 (a UTube showed the same bike with exact same gear worked well with 32 with B screw half way. Any advice ?

Posts

  • cruffcruff Posts: 1,518
    edited May 2020
    Rubbing in which combination? You're always going to get some rubbing (if it works at all) in 50/32, but should be able to get away with it in 34/32 - though the front mech might be a PITA to set up properly. When I did it, I couldn't get it to work without rubbing until i released some tension off the front mech cable. Even then, shifting took a good half hour or so to set up so that it was smooth (though i guess that's always going to be an issue with bigger cassettes because of the larger jumps between cogs)

    You'd be better off getting a wolf tooth mech hanger - they're only 20-odd quid
    Fat chopper. Some racing. Some testing. Some crashing.
    Specialising in Git Daaahns and Cafs. Norvern Munkey/Transplanted Laaandoner.
  • rideforfunrideforfun Posts: 8
    cruff said:

    Rubbing in which combination? You're always going to get some rubbing (if it works at all) in 50/32, but should be able to get away with it in 34/32 - though the front mech might be a PITA to set up properly. When I did it, I couldn't get it to work without rubbing until i released some tension off the front mech cable. Even then, shifting took a good half hour or so to set up so that it was smooth (though i guess that's always going to be an issue with bigger cassettes because of the larger jumps between cogs)

    You'd be better off getting a wolf tooth mech hanger - they're only 20-odd quid

    If im on small in the front and 32 in the back the upper jockey wheel is not far enough from the casette and the chain is not running smoothly in between
  • rideforfunrideforfun Posts: 8
    No issue with shifting between gears front and back
  • sandyballssandyballs Posts: 577
    I think your wrong with the manufacturer specs

    https://bike.shimano.com/en-EU/product/component/105-5800/RD-5800-SS.html
  • arlowoodarlowood Posts: 2,551
    rideforfun said:

    If im on small in the front and 32 in the back the upper jockey wheel is not far enough from the casette and the chain is not running smoothly in between

    Have you tried tweaking the B-screw. Set up the 34/32 combination you refer to the turn the B-screw clockwise to move the top jockey wheel away from the 32 sprocket on the cassette until it runs smooth.

    If you B-screw is already at it's limit and you are still getting rubbing the you can buy an extra long B-screw that will give you more leeway.

    https://www.sigmasports.com/item/Wolf-Tooth-Components/25-mm-B-screw/I9ZD
  • rideforfunrideforfun Posts: 8
    arlowood said:

    rideforfun said:

    If im on small in the front and 32 in the back the upper jockey wheel is not far enough from the casette and the chain is not running smoothly in between
    Have you tried tweaking the B-screw. Set up the 34/32 combination you refer to the turn the B-screw clockwise to move the top jockey wheel away from the 32 sprocket on the cassette until it runs smooth.

    If you B-screw is already at it's limit and you are still getting rubbing the you can buy an extra long B-screw that will give you more leeway.

    https://www.sigmasports.com/item/Wolf-Tooth-Components/25-mm-B-screw/I9ZD

    Thanks
    I think this will solve it
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