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  1. #1
    Gimme free stuff
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    Bottom bracket help

    So first off, I am not building a bike frame. I am designing and building a captains chair for a quadriplegic for a sonar sail boat. It will be similar to what can be viewed here but with a bunch of modifications.

    The design that I linked to above used a shimano un-55 bb, and a NOVA shell but they did not call out the dimensions of either. I have not done much bb work so I dont know what to use for either. (Parts are linked to the sites where they were purchased)

    My questions are:
    1) Which BB should I use with the NOVA shell?
    2) What will the width of the crank arms be with the specified bb?
    3) If I weld the shell, I assume it will still fit the bb as it is intended. Is this correct?

    Thanks for your help!
    Quote Originally Posted by Sparticus
    P.S. The true SSer's motto: "Do it anyway."
    Misfit DiSSent 29er
    Dawes Deadeye [FOR SALE]

  2. #2
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    Quote Originally Posted by tims5377 View Post
    So first off, I am not building a bike frame. I am designing and building a captains chair for a quadriplegic for a sonar sail boat. It will be similar to what can be viewed here but with a bunch of modifications.

    The design that I linked to above used a shimano un-55 bb, and a NOVA shell but they did not call out the dimensions of either. I have not done much bb work so I dont know what to use for either. (Parts are linked to the sites where they were purchased)

    My questions are:
    1) Which BB should I use with the NOVA shell?
    2) What will the width of the crank arms be with the specified bb?
    3) If I weld the shell, I assume it will still fit the bb as it is intended. Is this correct?

    Thanks for your help!
    I cannot access the chair link, requires an EDGE account. Therefor not really clear what you are trying to do.

    The BB is designed for a 68mm wide shell, the nova shell is intended to be faced down to final 68mm width deminsion after welding to ensure alignment and good bearing life. In practice, it would likely work fine to leave this shell at 69mm, the BB will still fit in fine. Threads of the shell should aslo be chased after welding to correct for any distortion.

    info on crank width/deminsions for typical shimano cranks can be found at;
    Shimano Framebuilder Info - Pvdwiki

    Depending on your fabrication skillset and tools, consider a steel shell rather than aluminum. THe weight savings of an aluminum shell on a boat are infintesimal. Aluminum is generally harder to work with unless you are a proficient TIG welder.

  3. #3
    Gimme free stuff
    Reputation: tims5377's Avatar
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    Quote Originally Posted by GrayJay View Post
    I cannot access the chair link, requires an EDGE account. Therefor not really clear what you are trying to do.
    P12031 / Home

    Link Fixed!
    Quote Originally Posted by Sparticus
    P.S. The true SSer's motto: "Do it anyway."
    Misfit DiSSent 29er
    Dawes Deadeye [FOR SALE]

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