2005 Shimano 105 triple to double conversion

Discussion in 'Cycling Equipment' started by watermelonman, Sep 22, 2014.

  1. watermelonman

    watermelonman New Member

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    I have an older Specialized Roubaix that I love, but that triple powertrain has driven me nuts one too many times. I am currently trying to convert it to a double.

    I heard the left control for shift/brake is, in fact, made to handle both double and triple chainrings. Can anyone confirm? Is there a setting for this inside the lever, or how does it work?

    What else should my concerns be? So far I plan on swapping front derailer, crankset, and bottom bracket.

    Thanks!
     
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  2. oldbobcat

    oldbobcat Well-Known Member

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    Shimano in fact intended the 5600 105 triple front shifter for double duty as well. The customary way to implement this is to lock out the third ring on the outside using the high limit screw, letting you shift between 1 an 2. Care must be taken to ensure there's enough tension in the cable that you're never tempted to pull past the second ring position.

    The problem is if the cable loosens and the upshift doesn't happen, the rider instinctively shifts again. This jams the shifter in the third position with cable up tight against the limit screw. The subsequent downshift against the tight cable either breaks the ratcheting mechanism right there, or if you do it often enough, it will break soon enough. This was occurring so frequently, often on bikes set up by shop mechanics, that Shimano hastily released a double front shifter for 5600. But, if you use care it will work. If you've found yourself shifted into the ghost third ring, just remember to dump the excess cable tension, by releasing the cable fastening bolt or loosening the high limit screw on the front derailleur, before downshifting. The happy news is that once your shift housing is seated cables don't stretch a whole lot until they're ready to break.

    The alternative that I've heard about is to lock out the non-existent inner ring so you're shifting between 2 and 3. The problem with this is that if you accidentally shift to one, you have a very slack cable that can get dislodged.

    Your triple front derailleur might work fine for double rings. So might your crank after you remove the inner ring. Chain line will need to be resolved. If you have Hollowtech II cranks, move the plastic shim on the drive side to the non-drive side. If your cranks use a cartridge bottom bracket, you will need a new one with a shorter spindle. Of course, if you replace all this it will go together seamlessly.
     
  3. watermelonman

    watermelonman New Member

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    Good to hear, and thanks for the confirmation. I purchased front derailer, chain, cassette, bottom bracket, and crank with chainrings and left the whole mess at my local shop. I cannot wait to pick it up and hope it shifts as well as other doubles I have ridden.

    I certainly can be careful with that front shifter, but do you foresee it becoming a problem? Should I preemptively swap for a different option, or hold off to see if there are problems over time?

    Thanks again!
     
  4. oldbobcat

    oldbobcat Well-Known Member

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    Shop mechanics should do this without asking, but since this is critical for your ride, request that they pre-tension the cables before turning the bike over to you. If they give you a funny look, you can do it yourself.

    Since this is an older bike, it will be easy to make sure the shift cable housings and ferrules are seated. Shift the chain to the big ring and give the front shift cable a sharp yank along the down tube. Then, watching the front derailleur cage and pulling the upshift lever, you should see no movement. If there is, the cable loosened. tighten it a click or two at the barrel adjuster and try the lever again.

    When you're satisfied the derailleur is hitting full cable tension the same time it's hitting the limit screw, try trim. The lever action should be light and the derailleur should drop back a couple millimeters. If this is not the case, back off the cable tension.

    Now you're read
     
  5. maydog

    maydog Well-Known Member

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    I have a newer Tiagra front triple shifter and double chainrings. I could not get the high lockout to work correctly, after a lot of tweaking I resorted to using the High, middle settings and letting the low be slack. This works just fine, the slack is not a problem.
     
  6. alfeng

    alfeng Well-Known Member

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    [color=FFa500] Uh-oh!?! [/color] THANKS for elaborating WHY the first generation of Shimano's 10-speed STI [color=ff0000]Triple[/color] shifters should not be used as a Double!
    • Of course, that make me wonder how peeved I should be that I have a now-vintage set of 6603 shifters ([color=808080]which you previously mentioned had the potential to suffer from the same malady in a prior thread[/color]) which is [color=008000]still in their box [/color]... :crying:
    Thank goodness THOSE were the last pair of Shimano shifters that I bought!!! :big-smile:
     
  7. oldbobcat

    oldbobcat Well-Known Member

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    I'm sure you could find a way to make them work with a triple MTB crankset.
     
  8. MikeWMass

    MikeWMass New Member

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    What I was posting has already been said. Sorry!
     
  9. stevegreer

    stevegreer Member

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    My '87 Trek 400 had a triple chainring crankset on it. All I did was remove the third chainring and left everything else the same. I just have to be very cautious when shifting so as to not derail the chain completely off the ex-middle chainring. Of course, I have friction shifters on the downtube, so that's not hard to do at all!
     
  10. watermelonman

    watermelonman New Member

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    Got it back a day or two ago and I am absolutely loving the change! It shifts nearly as nicely as my Dura Ace double, well worth the extra time and cost over the other maintenance I needed. I am not sure what the shop did to the left shifter but it feels like a double should, locking out on top and bottom where expected, and no weird kinks in the action between the two chain rings.

    Now all I need to do is pick out that wheel upgrade I have been agonizing over.
     
  11. oldbobcat

    oldbobcat Well-Known Member

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    Sounds like you have a good shop to go to. Bring them coffee and donuts as the holidays are approaching.

    For a wheel upgrade, consider Shimano RS-81s, available in several rim depths. It's a Dura-Ace alloy/carbon composite rim with an Ultegra-grade hub, 11-speed compatible so if you ever upgrade you can take the wheels with you.
     
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