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  1. #1
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    Advised to re-post this in here:

    OCLV Bottom Bracket Help!


    Hi All, great forum! I've recently acquired a 90s Trek oclv frameset with the intention of building a fun ultra light single speed commuter for my 15 mile round trip to work The problem is that the frame has a de-bonded bottom bracket sleeve. I do my own wrenching, and quite liked the idea of dipping my toe into the river of composite repair I've sourced a replacement sleeve (steel), and had intended to bond this in place and then use a threadless type bottom bracket. The interior of the bb shell is uneven, this means I would need to use an adhesive that also had some 'filler'
    qualities, and this is my biggest problem! Being new to composites etc I have no idea what to use! On top of this the frame was very inexpensive, and some of the adhesives that seem suitable cost more than the frame!
    Can anybody point me in the right direction? Thanks from a frustrated newbie

  2. #2
    Senior Member mudboy's Avatar
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    I'm no expert, but I'd guess that good old fashioned epoxy would work...
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  3. #3
    Senior Member Cassave's Avatar
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    Devcon FasMetal 10 would be a good choice.
    It's an aluminum filled, high strength epoxy with a long pot life.
    Has very good gap filling properties.

  4. #4
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    Thanks for that Any other suggestions?

  5. #5
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    The Fasmetal doesn't appear to be readily available here in the UK
    Does anybody know if Loctite 3423 would work?

  6. #6
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    Never had a Trek apart like that. First I would see if the BB frame shell port is carbon or fibre glass. I am assuming you will ride it in the rain. If water gets in, then you might have the making of a battery. The carbon if not insulated from different metals that are a distance away from the galvanic scale will corrode at one end or the other.
    A fibre glass layer will provide insulation.

    Then I would look up Crumpton cycles, in particular:

    http://www.velocipedesalon.com/forum...les-16366.html

    and poke around at his play by play of a frame build.

    Personally I would stay away from a carbon steel BB shell insert. On the use of aluminum or stainless steel, both have a short exposed time limit between cleaning and adhesive application / assembly. This is from marine and airplane experience / watching.

    Also, be sure to know the minimum and maximum adhesive thicknesses you can get away with or must maintain. My guess is that might have been the reason for the Trek's failure. What did the exterior of the shell insert that got loose look like?

    Did I mention that you may need to fixture this? Often the set / cure times of room temperature adhesives, even two part materials is quite long. I would not want it to move or settle and have no control.

  7. #7
    THE Materials Oracle Falanx's Avatar
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    I'd advise against the use of an aluminium filled epoxy in contact with carbon. The galvanic potential is about the same as a AA battery. Go for a steel-fileld one, such as what is sold over here as Chemical Metal and such....
    "While my father fought for you, I learnt. While my father glorified your petty administration, I learnt. While he longed every day for our line, Adun’s line, to be restored, I learnt. He sent me away to bring the Dark Templar back when the time was right!
    "And you tell me that I cannot do this? That I cannot feel the weight of the universe?
    "Damn you, Tellan! Aldaris killed my father!"

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