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  1. #1
    Senior Member
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    Jul 2007
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    09 Specialized Tricross Sport
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    MTB crankset + 130mm hub = bad chainline?

    Hello all,
    I'm looking into doing a build of a light touring road bike and I want to have lower gearing but I also want close ratios and higher end components. My initial thought has been to get a road cassette for the close ratios and an MTB crankset for effectively lower gears, namely 48/36/26 rings.

    So I viewed a recent QBP catalog and in it was listed Ultegra 9-speed shifters, and Ultegra 9-speed cassette and an Ultegra 9/10-speed rear derailleur. For a crankset, I was thinking about getting a Shimano XT 48/36/26 crankset. All 9-speed Shimano stuff so I shouldn't have any chain compatibility issues.

    Now the problem, as cited from BTI-USA:
    Includes 4-bolt 22/32/44t (M770) or 26/36/48t (M771) chainrings and BB set for 50mm chainline (135mm rear spacing)

    Uh oh. I was going to use 130mm hubs with a 130mm rear-spaced road frame.

    Can I just use a different bottom bracket that will give me a chainline more compatible with my road hub?
    Last edited by thirdin77; 08-19-08 at 01:17 AM.

  2. #2
    Low car diet JiveTurkey's Avatar
    Join Date
    Aug 2007
    Location
    Corvallis, OR, USA
    My Bikes
    2006 Windsor Dover w/105, 2007 GT Avalanche w/XT, 1995 Trek 820 setup for touring, 201? Yeah single-speed folder, 199? Huffy tandem.
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    Quote Originally Posted by thirdin77 View Post
    Can I just use a different bottom bracket that will give me a chainline more compatible with my road hub?
    Edit: the M771 uses a 2-piece crankset in which the spindle is permanently attached to the drive-side crank. You cannot swap spindles. Go with an older version or with another crankset that uses an Octalink, ISIS, or square-taper bottom bracket.
    Last edited by JiveTurkey; 08-19-08 at 02:17 AM.
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