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  1. #1
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    BB cup glue/epoxy

    Long story short my BB began "knocking" during a ride. Not a creek, but a knock.

    So I go to remove the BB. I remove the non-drive side without any problems. When I try to unthread the drive side the BB and the "BB cup"(?)both spin which keeps me from removing the BB. The "cup" is suppose to be glued/epoxied/molded into the carbon bike for the BB to thread into.

    So I take it to the LBS and they get the BB off and remove the "cup". The owner tells me I need to find a glue or epoxy to put on the "cup" so he can press it back in.

    I have done some searching and haven't come up with anything that sounds like it will adhear the aluminum "cup" to the carbon frame.

    Any suggestions would be GREATLY appreciated.

    Thank you.

    Sent from my Moto G (4) using Tapatalk

  2. #2
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    Wow, that is disconcerting. So he he wants you to find a "glue" ? that guy is not to be trusted? who sold the bike to you? what warranty do you have on the bike?

  3. #3
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    Second hand diamond back overdrive pro. No frame warranty... The shop owner is actually a very good guy but had never seen this before and didn't want to give me bad advice.

    He pressed the cup out for free and it was no easy task.

    I called Diamond Back and they said they could not give advice on repairs for "liability" reasons...

    Sent from my Moto G (4) using Tapatalk

  4. #4
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    so apparently he is a good man you have a rather difficult problem with that Bottom bracket . Any type of adhesive to secure that cup back into the bottom bracket shell will most likely fail, shame on Diamondback for bailing out on you. Maybe.....you could convert the bottom bracket shell to a threaded type cup. I refuse to buy frames that use press in cups, nothing but trouble. Hope you can salvage the bike.

  5. #5
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    Quote Originally Posted by jupiter58 View Post
    so apparently he is a good man you have a rather difficult problem with that Bottom bracket, so that is not a threaded bottom bracket? if not, my 1st thought is to convert to a threaded bottom bracket. So run that past your mechanic to see if that is possible. Any type of adhesive to secure that cup back into the bottom bracket shell will most likely fail, shame on Diamondback for bailing out on you.
    He bought it second hand, why shame on DB? Very few bike companies would warranty a frame for second hand.

    OP, I think you'll need some kind of two be part epoxy. I would clean/ sand the two interfaces very very lightly to get the existing stuff out. Don't sand too much though and re shape the interfaces.

    I think there won't be anything that particular to Al and carbon... So I'd just get the stickyest, gnarliest stuff available... And generous with it

    Sent from my Moto G (5) Plus using Tapatalk

  6. #6
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    It is a threaded BB already. I did a poor job of explaining the parts.

    I don't know what the part that is suppose to be glued into the frame is called. I guess it'd be the "female" part of the BB.

    I referred to it as a "cup" in the original post bc I didn't know what to call it.

    But yes, I need to know what type of adhesive I should try to fix the "female cup" back into the frame so the BB can thread back into it.

    And yes I was very disappointed with DB's lack of caring.

    Sent from my Moto G (4) using Tapatalk

  7. #7
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    I did not expect them to warranty the bike but at least point me in the direction of an adhesive...

    I agree that the two part stuff is probably the best thing I know of, but they can be pretty caustic and I was afraid of damaging the carbon or pitting the aluminum.

    I was hoping someone would know of some secret sauce out there that was concocked by an ex-rocket scientist that perfectly fuses carbon and aluminum.



    Sent from my Moto G (4) using Tapatalk

  8. #8
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    hope you can fix your bike.carbon fiber frames are difficult to work with.

  9. #9
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    Ok. I may need pictures for this but I'll do my best to explain real quick.

    The bike has a carbon frame.

    The BB is a threaded Hope.

    Where the drive side and the non-drive side of the Hope BB thread into the bike is an aluminum houseing that is threaded for the BB to thread into.

    This aluminum threaded houseing is suppose to be glued into the frame, so the Hope threaded BB can be threaded into the frame vie the glued in aluminum threaded housing.

    So the glue is for the outside diameter of the aluminum threaded housing to the inside diameter of the carbon frame.

    Clear as mud?

    I'll take pictures tomorrow to better illustrate the problem.

    I just got off work and it's time for bed. 2am central.

    Thanks for the help thus far.

    Sent from my Moto G (4) using Tapatalk

  10. #10
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    seems the threaded aluminium bottom bracket insert delaminated from the carbon fiber shell? how to replicate the factory method of bonding seems to be the issue. Difficult problem,sorry I can not offer any more help. I would not be optimistic about solving this problem any one know how common this problem is? carbon fiber frames have always scared me off in regards to this type of problem.

  11. #11
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    While working in bike shops, I had to fix BB sleeves into carbon frames on a few occasions. We did that after contacting the manufacturers and asking them what to do. Re-glueing a BB cup into a frame with 2-part epoxy is common practice. I did it on a few Cannondales and a Scott frame.
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  12. #12
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    Seems pretty straight forward. Glue it back in.

  13. #13
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    Quote Originally Posted by mack_turtle View Post
    While working in bike shops, I had to fix BB sleeves into carbon frames on a few occasions. We did that after contacting the manufacturers and asking them what to do. Re-glueing a BB cup into a frame with 2-part epoxy is common practice. I did it on a few Cannondales and a Scott frame.
    Any brand or mixture suggestions for the two part epoxy?

    Sent from my Moto G (4) using Tapatalk

  14. #14
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    On a road bike, I glued a Wheels Manufacturing thread-together press fit BB into a carbon frame where the carbon cups were totally wallowed out using JB Weld. Roughened up the outside of the BB aluminum and throughly cleaned out the CF shell. JB Weld is metal filled epoxy and sets up pretty hard and tough. It's gone a few thousand miles and is still holding tight.
    Do the math.

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