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  1. #1
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    Square Taper BB's - Mtn Triple to Road Triple

    I have a bike that uses a square taper bottom bracket, currently with a mountain 26-36-46 crank on it. is it safe to assume that a road triple will use the same width BB axle?

  2. #2
    Small Member maddmaxx's Avatar
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    I suspect that the road triple may want 5mm more bottom bracket length as it was originally optimized for a 130mm rear spacing chain line. This assumes that you are working on a modern MTB with 135mm rear spacing.

  3. #3
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    Actually, it's a Redline road bike with 130mm rear spacing. I'm not worried about having a screwed up chainline as long as it gets me from work and back.

    Am I to assume that this would probably work? I tried putting a double on the BB, but the small ring, a 42, came really close to rubbing against the frame, so i didn't even bother trying to actually ride it. It seems reasonable that the small ring on a triple would probably allow for more space between the chainrings and the chainstay.

  4. #4
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    Quote Originally Posted by lordconqueror
    I have a bike that uses a square taper bottom bracket, currently with a mountain 26-36-46 crank on it. is it safe to assume that a road triple will use the same width BB axle?
    No. The crankset manufacturer sets the spec for the bb spindle length.

  5. #5
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    alright, gotcha.

  6. #6
    Your mom
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    Check out Sheldon's page for cranksets and associated BB spindle lengths.

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