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  1. #1
    Senior Curmudgeon
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    130 BCD cranks for MTB?

    I've got a Specialized Rockhopper with a 4-bolt triple crank. The crank arms are "bent out" to clear the wide rear chainstays. I'd like to use a 130 BCD chainwheel (single) with chain guards instead. Does anyone make a 130 BCD crankset with "bent out" cranks for clearance?

    Thanks!

  2. #2
    Senior Member Retro Grouch's Avatar
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    What size chainring are you planning to use? If your bottom bracket is long enough to make your chainring clear with a reasonable chainline I can't imagine you having a crank arm clearance problem.

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    Quote Originally Posted by Retro Grouch
    What size chainring are you planning to use? If your bottom bracket is long enough to make your chainring clear with a reasonable chainline I can't imagine you having a crank arm clearance problem.
    The chainring is only a 46T. The chainstays, however, bow out CONSIDERABLY immediately aft of the bottom bracket (to clear any MTB tire that might be fitted). It is the crank-arm/chainstay clearance that concerns me.

  4. #4
    Senior Member mechBgon's Avatar
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    Actually, almost any crankset should work on your Rockhopper if it's paired up with the bottom bracket it was made to use. I know it probably doesn't look that way when you look at yours, but there you go.

    edit for clarity: with a 46-tooth ring, that is. If you slapped on a huge chainring, then it might have clearance issues.

  5. #5
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    Quote Originally Posted by mechBgon
    Actually, almost any crankset should work on your Rockhopper if it's paired up with the bottom bracket it was made to use. I know it probably doesn't look that way when you look at yours, but there you go...
    Thanks, mechBgon! As I understand you, appearances are deceiving, and provided that the chainrings don't cause problems, the cranks themselves should clear even without the crook in the crank arm?

  6. #6
    Senior Member mechBgon's Avatar
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    Quote Originally Posted by FarHorizon
    Thanks, mechBgon! As I understand you, appearances are deceiving, and provided that the chainrings don't cause problems, the cranks themselves should clear even without the crook in the crank arm?
    Yeah. If you could measure the width across the inside tips of the crankarms on a bunch of different triple cranks mounted on their appropriate bottom brackets, there'd be some variation, but not tons.

    To take an example, if you looked at an old Sugino AT crankset from the 1980's, its arm has no "crook" at all, it's basically straight. But it's made to go on a super-long spindle that still gets it out clear of the frame. Your cranks are the opposite... the spindle is short, so the arm has that kickout to get the crankarm clear of the frame. That crook in the arm isn't because of the shape of your particular frame, really, it's because the crank's made to go on short spindles.

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