Changing to bigger cassette

ForumNewbie
ForumNewbie Posts: 1,664
edited March 2015 in Workshop
I am thinking of changing the cassette on my carbon road bike from an Ultegra 11-28 (10 speed) to an Ultegra 12-30 (10 speed). It has a compact 50-34 chainset and all the drivetrain components are Ultegra so I am hoping it will be compatible. However I would like to know whether I would also need to change the rear derailleur or any other components on the drive train?

Comments

  • Zerotails99
    Zerotails99 Posts: 127
    No it will be perfectly fine. Chain might get slightly stretched When on 50/30 but it will cope ok.
  • dj58
    dj58 Posts: 2,223
    If your RD is the Ultegra RD-6700-A SS, then it is rated for a max rear sprocket of 30T so will be fine. If you are fitting a new chain as well as the 12-30T cassette then size it appropriately if you what to use the 50T-30T combination. Remember to adjust the B tension screw to give the required clearance between the 30T sprocket and the RD top guide pulley.
  • ForumNewbie
    ForumNewbie Posts: 1,664
    Thanks for the responses. I don't know if the RD is a 6700 - I don't think it says on it? All I know is that it's a 10 speed RD on a 2011 bike.

    I wouldn't anticipate ever using the 50/30 gear - when going into the 30 cog I would almost certainly have dropped down to the 34 ring at the front, so hopefully it will be okay.
  • dj58
    dj58 Posts: 2,223
    Does it say ultegra, 105, Tiagra, they usually have the group series name screen on, unless it is a non-series model, you have the spec for your bike? I agree regarding cross chaining 50T -30T, it is something I don't do myself. http://cycle.shimano-eu.com/content/seh ... leurs.html
  • peat
    peat Posts: 1,242
    Might aswell change the chain if you're doing the cassette. Make it a few links longer to compensate.

    In theory, yes, you should never be in a situation where you end up in big/big. But you'd feel a right knob if you ended up in that gear, knackered, not concentrating, miles from home and destroying your rear mech.
  • ForumNewbie
    ForumNewbie Posts: 1,664
    DJ58 wrote:
    Does it say ultegra, 105, Tiagra, they usually have the group series name screen on, unless it is a non-series model, you have the spec for your bike? I agree regarding cross chaining 50T -30T, it is something I don't do myself. http://cycle.shimano-eu.com/content/seh ... leurs.html
    It's definitely Ultegra - I just don't know whether it's 6700 as it doesn't seem to say that anywhere.
  • ForumNewbie
    ForumNewbie Posts: 1,664
    Peat wrote:
    Might aswell change the chain if you're doing the cassette. Make it a few links longer to compensate.

    In theory, yes, you should never be in a situation where you end up in big/big. But you'd feel a right knob if you ended up in that gear, knackered, not concentrating, miles from home and destroying your rear mech.
    Yes, I think I'd probably change the chain as well. I was thinking of putting on a KMC chain with missing link, which will presumably be okay with the Ultegra set-up?

    I have never changed a cassette before. Presumably it is easy enough with the correct tools?
  • peat
    peat Posts: 1,242
    Yeah, you'll need a cassette tool, chain whip & a chain tool. You should find plenty of Youtube tutorials.

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