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change compact crank to triple

  • 25-11-2013 8:12pm
    #1
    qwertier
    Registered Users, Registered Users 2 Posts: 6 ✭


    Hi,

    I want to change my compact crank set to a triple for some mountain training abroad over the winter.
    I currently have a compact crank set but want to have the have the option of more gears and so want to swap to a triple.

    My question is do I need to change my front derailer or will the current Shimano 105 be able to handle the change ups and downs?

    Thanks


Comments

  • #2
    rab!dmonkey
    Registered Users, Registered Users 2 Posts: 634 ✭✭✭rab!dmonkey


    What cassette do you have? You might be better served by switching to a 28t or 32t (you'll need a medium cage rear mech for that) low cog.


  • #3
    No Pants
    Closed Accounts Posts: 3,347 ✭✭✭No Pants


    Changing to a triple will also require a new shift lever. Not sure how the front derailleur will cope with three rings, one significantly smaller than before.


  • #4
    Raam
    Registered Users, Registered Users 2 Posts: 14,318 ✭✭✭✭Raam


    You could get away with a 28 with a short cage. I've seen a 30 cassette on a short cage Shimano Ultegra and I've used a 29 on a short cage Campag Super Record.

    I would go with the bigger ratio cassette with the compact before going to a triple. Unless you are already struggling with small hills and your abroad training will be in the Dolomites.


  • #5
    countrykid
    Closed Accounts Posts: 835 ✭✭✭countrykid


    Even if you have to change the rear mech to a long cage mech and put on a 32 tooth cassette it will work out cheaper, lighter and better than a triple...


  • #6
    cdaly_
    Registered Users, Registered Users 2 Posts: 6,440 ✭✭✭cdaly_


    No Pants wrote: »
    Not sure how the front derailleur will cope with three rings, one significantly smaller than before.
    It won't. A triple front derailleur has a much wider inner plate so that it can pick up the chain from much lower down. Without that, shifting from small to middle ring would be very sloppy.


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  • #7
    joxerjohn
    Registered Users, Registered Users 2 Posts: 396 ✭✭joxerjohn


    This change from a compact 50/34 to a triple 50/39/30 requires

    A triple compatible LH shifter
    A triple compatible front derailleur
    A long cage rear deraileur

    And a new/longer chain.

    So changing the cassette to one with a 28t or even a 30t to work with your existing set would be the best course of action.

    If you go to a bike shop they would probably allow you to try a wheel with 30t cassette to see if that would work on you bike. You could then order the cassette from them. Otherwise if you are in a club someone with a 30t would also oblige.


  • #8
    smacl
    Moderators, Society & Culture Moderators Posts: 15,812 Mod ✭✭✭✭smacl


    cdaly_ wrote: »
    It won't. A triple front derailleur has a much wider inner plate so that it can pick up the chain from much lower down. Without that, shifting from small to middle ring would be very sloppy.

    Don't think it would work at all, cage on a triple FD is wider at the bottom to accommodate the granny ring when the chain is lower, and narrow at the top to get into the big ring.. A double FD wouldn't let you get to the granny ring.


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