9sp/tiagra/bigger range cassette

Sprool
Sprool Posts: 1,022
edited February 2016 in Workshop
Work colleague new to road biking has a 9 speed tiagra set up with 12-27 cassette and what looks like a small cage derailleur. I reckon to help him up the Yorkshire hills he would be better off with a 30 cog on the back. Can the cage be changed to long or med (if that's enough?) without having to replace the whole rear mech? Suggestions and advice appreciated

Comments

  • MikeBrew
    MikeBrew Posts: 814
    I've read quite a lot of forum posts that seem to indicate that short cage 105 RD's will work with a 30T. Whether that also holds true for Tiagra, I know not, but it would appear to be likely(ish). Saying that though, Sora rear mechs ( Circa £15) are a cheap alternative to risking frame damage from a catastrophic mech malfunction !
  • arlowood
    arlowood Posts: 2,561
    I've run a short cage 105 5700 10-speed rear mech with a 12-30 Tiagra cassette on 3 different bikes with no problems.

    On one occasion I had to tweak the B-tension screw to get the top jockey wheel to have sufficient clearance but otherwise all was fine.
    If you do fit a new 9-speed cassette with 30t large sprocket make sure you fit a new chain of the correct length.
  • slowbike
    slowbike Posts: 8,498
    the 105 short mechs are fine on a 30t - but that's on a 10 speed.

    My 9 speed tiagra is a long cage (it may be called medium I don't know) and is fine with my max 32t ...

    not that helpful I guess ;)

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