Front derailleur adjustment

Discussion in 'Cycling Equipment' started by Apis, Mar 14, 2010.

  1. Apis

    Apis New Member

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    So, greetings everyone.

    I have a JPWeigle that I am looking to change the chain rings on. The 53 & 39 were originally on there for racing (it has a 12-26 eight sp. cassette). I like the cassette, and it has thousands of miles left on it. If I chuck on 48 & 36 tooth rings would I have to lower the front der. any?

    If it matters the mechanism is a Shimano 105 STI set up.
     
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  2. Peter@vecchios

    [email protected] New Member

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    Chances are the bolt diameter(130mm?) means that the smallest inner ring you can mount is a 38t. If ya put on a 48t, yes, lower the FD so that the outer cage is about 1mm above the big ring.
     
  3. alfeng

    alfeng Well-Known Member

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    You don't have to do anything if you don't care how poorly the front derailleur shifts the chain ...

    If you want to maximize the shifting's efficiency, then you will want to lower the front derailleur so that the bottom of the outer plate of the derailleur cage is a couple of millimeters above the teeth on the outer chainring -- observe the current gap and try to reset the front derailleur accordingly with the smaller, outer chainring.
     
  4. Apis

    Apis New Member

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    I'll have to check BCD...forgot all about that. Still, a 38T wouldn't be a deal breaker.
     
  5. Apis

    Apis New Member

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    Thanks for the replies. They are as I suspected, but I always seek validation of my opinions.
     
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