New cassette on 10sp Tiagra

dugliss Posts: 235
edited October 2013 in Road beginners
Is it possible to fit a 11-32 or 12-32 cassette on to a Giant Defy that already has a 12-30 Tiagra on it or will I need to change the rear derailleur or chain?


  • chrisaonabike
    chrisaonabike Posts: 1,914
    Not according to this.

    Seems to say 30T is max for the cassette with the standard RD. I changed from 12-28 to 12-30 without any problems, but consensus seems to be that a MTB mech is what you need for an even lower bottom gear. Way outside my expertise, but doubtless someone that knows will be along shortly.
    Is the gorilla tired yet?
  • dj58
    dj58 Posts: 2,217
    edited October 2013
    I doubt it, you would need to change the RD to a GS Long Cage model, however the Tiagra Cassettes are only available in 11-25T, 12-28T and 12-30T, According to Tech Support/Tech. Docs/ Road Bike/ TIAGRA. Assuming that you have a 50/34T Chainset 34T/ - 30T is fairly low. I suggest you go back to the bike shop that supplied the bike and ask them what your options are.
  • jibberjim
    jibberjim Posts: 2,810
    It's quite likely that'll work, it's not far out of the spec and many people have no problem running that set up. Maryka runs 34x32 regularly with the 6600 ultegra short rear derailleur which are rated only to 28, going just 2 out of range is normally no problem. Exact chain lines and chainstay lengths and things can impact it though.

    Any Shimano (or SRAM) 10speed cassette will be compatible, it doesn't have to be a Tiagra.
    Jibbering Sports Stuff:
  • dj58
    dj58 Posts: 2,217
    I stand corrected. Shimano MTB SLX 10 Speed CS-HG81-10 BL is 11-32T. Don't know whether it is compatible with your road bike Free hub body though?
  • It's not officially supported however chances are it'll work.