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  1. #1
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    Help with bottom bracket spindle length on 04 Epic

    I need some technical advice. Here's my situation:

    I have an '04 Epic. When the bike was new, I had bad chain skip and shifting problems. After repeated returns to the shop for re-tuning, my LBS replaced the stock cranks with with Deore XT FC-M752. Still had the problem. Finally one of the mechanics put a spacer between the bottom bracket and the frame shell. The problems then went away, so I assume it was a chain line issue that was resolved by moving the drive side crank out by the width of the spacer (which looks to be about 2.5 mm).

    Fast forward to now. Bottom bracket is getting some play and ready to be replaced. I pulled it out and it is a Shimano BB-ES70, 73 x 113 mm. I am not sure if the LBS also replaced the bottom bracket when they first replaced the cranks.

    What size bottom bracket do you think I need to get the proper chain line? Is spindle length dependant on the crank, or the bottom bracket shell width? I have found info that the M752 cranks are designed to work with either a 113 mm or 118 mm spindle length. If my logic is correct, I should be able to go with the 118 mm and ditch the spacer, since it's a 2.5 mm spacer. Does this make sense?

    However, I also found this post http://forums.mtbr.com/showthread.ph...43#post2625043 that said: "The 03 Epics that were speced with splined bb's used a 113mm spindle length, in 04 they went to a 121mm, and then in 05 to a 118mm spindle." If that's the case, I've had the wrong spindle length all along! Should I then go with a 121 mm? That's a big jump from the 113 that's been on there.

    Thanks in advance -- want to make sure I order the correct size...

  2. #2
    Trying a little
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    73mm? my 04 is 68mm

    I never apologize. I'm sorry, but that's just the way I am.

  3. #3
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    Hmmm...

    Quote Originally Posted by dusthuffer
    73mm? my 04 is 68mm
    I just measured it; it's definitely 73 mm -- unless I am measuring wrong??
    Last edited by lytleric; 03-26-2008 at 09:21 AM.

  4. #4
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    I just got off the phone with Specialized -- and you're right! Bottom bracket shell width was 68 mm... I'll need to re-measure later tonight; I must have been reading it wrong...

    But the strange thing is that the BB I pulled out of there is 113 mm, which means my LBS must've put the wrong size in there.

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