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Discussion Starter · #1 ·
I want to set my M952 XTR cranks up as a 2x9 using the Middleburn 104 bcd spider and Extralight 30t ring. For a better chinline/lower q-factor/less weight, I'd like to use a Dura-Ace 7700 Bottom Bracket. The problem is, it is only available in a 68mm width and my frame is 73mm.

Any way to make this work?
 

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Depends on how much money you want to spend on making it happen. The only way to make it work would be to find a shop that has bottom bracket facing tools and to have them cut the shell down to 68 mm then hand thread the bb cups in to make sure the threads are deep enough. If they aren't then they'll have to use a thread tap set to extend the threads. I would assume any shop that has bottom bracket facing tools also has the taps and I would expect this to cost between $100 and $150 by the time your done. Also before going foreward with the cutting make sure you can cut that much off the shell without hitting any of the welds on the downtube or chainstays. Shouldn't be a problem but just check first.
 

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Discussion Starter · #3 · (Edited)
I was kinda hoping that I could just put some 73mm cups on the BB. I know that older UN72 BBs had removable aluminum cups, and it is the cups that dictate the shell width. I just don't know if the cups are all the same ID (seems like they should be??).

Anyone know if these are available? Anyone have a QBP catalog handy?

edit: removable cups, like this:


Double Edit: Doh, that won't work due to the fact that DA BBs need an adjustable cup with a lockring.
 

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The cups are the bearing races on the dura ace also as they use roller bearings with a set of loose balls to the outboard side of the rollers. Maybe an ultegra octalink style bottom bracket? I think those are a seled bearing type unit. Anything except Cannondale Si or pinarello MOST are a standard shell diameter.
 
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