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  1. #1
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    Stripped BB shell

    I'm riding a circa 2005 Fuji Team SL (aluminum) frame with ISIS bottom bracket. Creaking like crazy because the BB shell threads are stripped on the NDS. I've tried a JB Weld clear epoxy to fix the NDS cup in place, seemed to work initially but within 20 miles started creaking again and now after 3 rides and 60 miles the creaking is back full-on. Existing crank arms are of course ISIS splined. Options I've considered:

    - Better epoxy
    - rethread Italian (anybody know if a Italian threaded cup has same ID as an ISIS cup?)
    - Threadless bottom bracket w/square taper and new crankset
    - ???

    Suggestions/recommendations?

    The cup on the NDS appears to only provide support for the cartridge bearing/spindle and its not backing out, just not clamping tight so I'm not really worrying about a catastrophic failure on the road but is there any potential damage I could be causing?

  2. #2
    'brifter' is a lame word.
    Reputation: cxwrench's Avatar
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    Quote Originally Posted by sdjeff View Post
    I'm riding a circa 2005 Fuji Team SL (aluminum) frame with ISIS bottom bracket. Creaking like crazy because the BB shell threads are stripped on the NDS. I've tried a JB Weld clear epoxy to fix the NDS cup in place, seemed to work initially but within 20 miles started creaking again and now after 3 rides and 60 miles the creaking is back full-on. Existing crank arms are of course ISIS splined. Options I've considered:

    - Better epoxy
    - rethread Italian (anybody know if a Italian threaded cup has same ID as an ISIS cup?)
    - Threadless bottom bracket w/square taper and new crankset
    - ???

    Suggestions/recommendations?

    The cup on the NDS appears to only provide support for the cartridge bearing/spindle and its not backing out, just not clamping tight so I'm not really worrying about a catastrophic failure on the road but is there any potential damage I could be causing?
    The fact that you have an ISIS bottom bracket in your bike has nothing to do w/ whether it's Italian or English thread, you could have one either way depending on your frame...that's what matters. Your English bb shell is 68mm wide, an Italian shell is 70mm wide. In theory you could cut Italian (36mm x 24tpi) threads in a previously English (1.37" x 24tpi) and add a 1mm spacer to the drive side of an Italian bottom bracket. In reality...good luck.
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  3. #3
    Rub it............
    Reputation: frdfandc's Avatar
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    Have you had the threads chased?

    Also, why stick with ISIS or square taper. Why not go with something newer like external BB with either a Sram or Shimano crank?
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  4. #4
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    You epoxied your bb into your stripped bb shell and you are asking if you could cause damage?

    Thanks for the laugh.
    Last edited by crit_boy; 08-11-2018 at 12:44 PM.

  5. #5
    Matnlely Dregaend
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    You definitely don't want to fix this yourself. My guess is the shell would wind up too thin if re threaded 36mm Italian, and for sure too thin for anything press fit. BB30 is 42mm, BSA is 35mm. The alignment of both sides as well as the dimensions are pretty critical, you really need the right (and expensive) tools to do it right. If you move to something that uses cups (Campy Ultratorque would work for sure, not 100% sure Hollowtech would work) you could try re threading only the ND side and using mismatched cups. But again the alignment would be critical and I don't know how you would align mismatched thread sides as I don't know any tools that support that (edit - I think the $600 Park BB tool would do it but you'd also have to buy the $200 Italian tap (or $400 if you want both sides) - a new frame would be cheaper)

    One could tig weld in a new BB, and repaint, but as it's an Alu frame.... I would replace it.
    Last edited by DrSmile; 08-12-2018 at 06:27 AM.
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  6. #6
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    In the late 80's or early 90's, Mavic sold a square taper cartridge like BB that did not use the BB threads and was perfect for those with stripped threads. It was made for exactly your situation The cartridge tightened down against the BB shell faces which required something like a 5deg taper to ensure the BB was aligned correctly to the frame. Perhaps you can track a used one down on ebay.

  7. #7
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    Further from my prior response, I found a link that shows and describes the Mavic BB I was describing: Mavic Bottom Bracket - Bicycle Parts at discount prices / the Buyer's Guide / Bicycle Parts at their finest! / Professional Bicycle Source / Bike Pro

    I was a little off with angle at which the BB shell face had to be chamfered - it's 45deg rather than the 5deg I stated.

    If you cannot find a Mavic BB, then Google "threadless bottom bracket for damaged frames", which will uncover other square taper BB's that work just the same that are still sold.
    Last edited by RHankey; 08-13-2018 at 06:51 AM.

  8. #8
    'brifter' is a lame word.
    Reputation: cxwrench's Avatar
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    Then all he'd have to do is track down a shop that has the Mavic tool to cut the chamfer on the bb shell.
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  9. #9
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    Quote Originally Posted by cxwrench View Post
    Then all he'd have to do is track down a shop that has the Mavic tool to cut the chamfer on the bb shell.
    Ideally yes. However, I have seen some use these Mavic (or Mavic like) threadless BB's without cutting the chamfer. Not ideal, but workable. The cups just won't seat fully into the BB shell, which moves the chainrings out 1/8" or so when done.

    In any event, the threadless BB's is a lot better a solution than attempting to convert the BB shell to Italian threading as you or someone else seemed to suggest. You'd only be able to convert one cup from English to Italian thread. Attempting to convert the left hand threaded English thread to an right handed Italian thread would leave an ugly stripped mess.

  10. #10
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    Thanks everyone for all the input. Not ignoring y'all but didn't really have anything to report till now. Long story shortened, I've been to a bunch of local shops all of which initially offered up variations on 'good luck with that'. Latest one said they'd been successful cleaning up threads that looked worse than mine... chased the thread both sides, installed the BB from the drive side, and had to back it out to even get any threads to engage on the NDS cup, and couldn't torque it at all because it felt like it was going to strip the threads. Within 5 miles of riding it was back to creaking like crazy. Sigh.

    Probably will go the threadless route soon, the Velo Orange Grand Cru looks good - it has some sort of expanding sleeve to lock it in place.

    Quote Originally Posted by cxwrench View Post
    The fact that you have an ISIS bottom bracket in your bike has nothing to do w/ whether it's Italian or English thread, you could have one either way depending on your frame...
    Thanks for pointing that out, I'd only seen English thread units advertised. One of the shops I went to had an Italian threaded one, but the ID of the cup was a different size than mine and they didn't have taps for Italian thread anyway.

    Quote Originally Posted by frdfandc View Post
    Have you had the threads chased?

    Also, why stick with ISIS or square taper. Why not go with something newer like external BB with either a Sram or Shimano crank?
    Now yes, and threadless with external bearings are sparse, I've only seen the YST BB-0901 in that configuration, and need to research it more.

    Quote Originally Posted by crit_boy View Post
    You epoxied your bb into your stripped bb shell and you are asking if you could cause damage?

    Thanks for the laugh.
    Glad to be of service, it does really sound odd that way! Actually, I was wondering more specifically if riding it with the NDS loose might result in damage to the good threads on the DS. If annoying creaking is the only downside of riding it the way it is now, I don't have to be any more hasty than I've already been...

    Quote Originally Posted by DrSmile View Post
    You definitely don't want to fix this yourself. My guess is the shell would wind up too thin if re threaded 36mm Italian, and for sure too thin for anything press fit.
    Tried to research this a bit. Didn't find any truly pertinent info so far, but did find a couple of framebuilding supply web sites with pre-threaded aluminum shells. One site had 43mm od shells threaded either English or Italian, the other had a 41mm od shell only available threaded English. My shell measures 43 mm od so it MIGHT be okay. I also found a site that offers an 'Italian to English' insert pair, kinda like Helicoils. Sent them an email asking what they think but haven't heard back yet. If I decide to chance it I'll definitely find a local shop to do the tapping.

    Quote Originally Posted by RHankey View Post
    In any event, the threadless BB's is a lot better a solution than attempting to convert the BB shell to Italian threading as you or someone else seemed to suggest.
    Yeah, sounds like the better way to go. Time to research and decide.


    Thanks again, all.

  11. #11
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    Quote Originally Posted by sdjeff View Post
    Now yes, and threadless with external bearings are sparse, I've only seen the YST BB-0901 in that configuration, and need to research it more.
    Yeah, sounds like the better way to go. Time to research and decide.
    If you are having any trouble tracking down someone with the 45deg chamfering tool required to fit a threadless BB properly, it is possible to cut the chamfer with a file while using the cups as a guide to see where you still have high spots. Lay the frame on its side while filing. If you don't feel mechanical enough to do this on your own, a machine shop would have the filing job done in 15 to 20 min tops.

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