Replacing compact with triple, whats required?

kangar Posts: 12
edited July 2012 in Workshop
A friend of mine (no really, I am asking this question on behalf of a friend) wants to replace his compact chain set with a triple. He's wondering what else he would need to replace. Does he need a new shifter and front mech? His bike has 105 components throughout. Cheers


  • freezing77
    freezing77 Posts: 731
    New front shifter, new front mech, new rear deraileur maybe(long/medium cage), new chain maybe, new chainset. Starting to get very expensive.
  • DNQ
    DNQ Posts: 45
    Might get away without a new left shifter, the earlier ones were both double/triple compatible, best way to test is to disconnect the cable and see how many "clicks" 2 full clicks indicates a triple compatible shifter (beware the half or "trimming" clicks). There should be a model number, but I couldn't find it on mine.
    If "your friend" wants a granny gear smaller than 30 teeth, check that the inner ring has a BCD of 74mm. I think the 105 ones still are, but Tiagra are "triplized" (meaning the granny ring piggy-backs off the middle ring) with a BCD of 92mm (smallest available ring is 30 teeth).
    As freezing77 points out, not a straightforward conversion.
  • freezing77
    freezing77 Posts: 731
    edited July 2012
    As a thought how about one of the newer SRAM wide range road cassettes with maybe a new medium /long cage rear derailleur. Will probably give the same range as a triple with the existing cassette.

    SRAM PG-1050 11-32t or 11-36t
  • kangar
    kangar Posts: 12
    Thanks for the responses. I didn't think this would be easy and your advice confirms this. I think a different cassette might be the answer....for my friend :wink: