Shimano 105 cassette query

vilhelms Posts: 19
If I'm running an 11-28 cassette, can I safely switch it out for an 11-34, or would it impact the derailleur/require a longer chain. Is there a logical max size increase if I retain my existing chain and derailleur? Thanks


  • johngti
    johngti Posts: 2,508
    You’d need a longer chain but you could just add a couple of quick links if you’ve got bits of chain hanging around. You’d also need the cassette spacer and to check the limit screws, plus a cable tweak probably.
  • daniel_b
    daniel_b Posts: 11,773
    +1 to the above.

    Have you checked the spec of your rear derailleur?

    It may only be able to go up to 28 or 30, although there is some fettling you can do with the B screw.
    Or buy a derailleur extender.
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  • gethinceri
    gethinceri Posts: 1,577
    Spacer? Why on earth would he need a spacer?
  • johngti
    johngti Posts: 2,508
    The 11-34 cassette needs it on an 11-speed hub. Something to do with the spacing. It’s not needed for anything less than that.
  • Munsford0
    Munsford0 Posts: 647
    Are we talking 11 speed 105 or older 10 speed stuff? What rear derailleur?

    I went 11-32 on my 10 speed 5700 GS rear mech without any faffing with the B-screw
  • N0bodyOfTheGoat
    N0bodyOfTheGoat Posts: 6,000
    11-34 road 11-speed comes with the spacer that goes behind the cassette on an 11-speed freehub.
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