Changing a double to a triple chainring

Discussion in 'Cycling Equipment' started by James Lodberg, Aug 22, 2003.

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  1. > Was RE:Convert 105 STI double to triple?
    >
    > I'm planning on getting a triple crank for my road/touring bike. Is it possible to upgrade my
    > double/8-spd 105 STI levers to work with the triple, without having to replace the whole lever?
    [snip]

    Howdy again,

    Sorry folks, I missed the thread from earlier this year! Let me elaborate on my situation, see
    comments below:

    > "Fred" <[email protected]> wrote in message
    > news:[email protected]...
    > > I have a Raleigh R700 with double 105 chain ring. I recently moved to the mountains and
    > > desperately need a triple crank (ok, I am a wimp). Can I easily change out the crank/chain rings
    > > but use the same front derailer?
    > >
    > > Thanks
    >
    > Lots of ppl have done this.
    >
    > You'll need a triple FDR, a long cage RDR, a triple crankset, and a longer bottom bracket (the one
    > recommended for the crankset).

    I have all this - the bike actually used to be my triple/8-spd XC mountain bike, now converted to a
    road & touring machine. I still use the long-cage rear derailleur, and triple front derailleur
    together with newly acquired, albeit used, drop bars & 105 STI levers. The crank is a TA Zephyr with
    the granny ring removed. This setup works great - no compatibility or shifting problems at all. I
    also have a spare bottom bracket with a 2.5mm longer axle, and a small chainring, both of which
    gather dust til the day I get a triple shifter.

    > You MAY need a new left shifter

    That's what I'm trying to avoid, due to cost...

    > Shimano shifters (Tiagra and up - Shimano 105 ST-55XX) are double/triple compatible - older
    > Shimano stuff is double (Shimano 105 ST-1055)or triple (Shimano 105 ST-1055-T) only

    ...and the fact that I can't buy a new one anyway (I have the old ST-1055, and would like to stay
    with them for now)

    > check the Shimano Europe site - http://www.shimano-europe.com/cycling/index.phtml or here -
    > http://www.fa-technik.adfc.de/Hersteller/Shimano/DIGEST.html for older stuff.

    Great link - thanks! I'm hoping to be able to simply replace the ratchet unit in the left shifter
    with the ratchet from the triple version (see link to image, below).

    http://www.fa-technik.adfc.de/Hersteller/Shimano/G/ST-1055.gif

    Or is there more to it than this?

    > Changing the cassette to something with larger sprockets is an alternative, and cheaper,
    > option, but you will end up with larger steps between the sprockets - this may or may not be
    > acceptable to you.

    Good advice, but it's not for me. Part of the MTB-road conversion involved ditching the MTB cassette
    in favour of a nice close-ratio 12-23T road cassette. (I love to spin!)

    Cheers, James
     
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