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Thread: BB threading

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    BB threading

    I currently have a 68mm traditional 3 piece cup and cone bottom bracket.
    if the cups tighten like british/iso (left side tightens right, right side tightens left) style bottom brackets, does it necessarily mean that the thread sizing is that of a british/iso style bottom bracket (1.370" X 24 tpi)?
    then if this is true, upgrading to a sealed bb should work? and if it doesn't i'm screwed?
    I could pull out the cups and measure the threads, but i spent a good part of today fitting/hammering/smashing/grinding the cotters all nice like to fit. I don't want to do it again.

  2. #2
    Senior Member bikeman715's Avatar
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    yes a sealed bb will work for you.
    bikeman715

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    coprolite fietsbob's Avatar
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    Brit standard, used by Japan and exporting Asian manufacturers . too.


    I went Ah Ha! when I found Cotter Presses to do those jobs,
    on old cottered cranks.
    pushed rather than beat them out, so they get reused.
    the job got civil ..
    Last edited by fietsbob; 10-28-10 at 07:43 PM.

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    Senior Member cracker7213's Avatar
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    +1

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    Insane Bicycle Mechanic Jeff Wills's Avatar
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    Quote Originally Posted by sageo3000 View Post
    I currently have a 68mm traditional 3 piece cup and cone bottom bracket.
    if the cups tighten like british/iso (left side tightens right, right side tightens left) style bottom brackets, does it necessarily mean that the thread sizing is that of a british/iso style bottom bracket (1.370" X 24 tpi)?
    No. Especially if the bike is old enough to have cotters. If it's a Raleigh, you could have 1 3/8" X 26 tpi threading, in which case the only sealed BB that fits is a Phil Wood. (See http://www.sheldonbrown.com/cribshee...mbrackets.html ) If the bike's Japanese, it's almost certainly English threading.
    Jeff Wills

    All my bikes.

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    it's not a raleigh. but people have aged my bike to about the 60's.

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    Insane Bicycle Mechanic Jeff Wills's Avatar
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    Quote Originally Posted by sageo3000 View Post
    it's not a raleigh. but people have aged my bike to about the 60's.
    Is the brand marked anywhere? If it's not a Raleigh, there's a 99% chance it's English thread, but I ran into a couple weird ones back when I was working in a shop.
    Jeff Wills

    All my bikes.

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    Quote Originally Posted by sageo3000 View Post
    I currently have a 68mm traditional 3 piece cup and cone bottom bracket.
    if the cups tighten like british/iso (left side tightens right, right side tightens left) style bottom brackets, does it necessarily mean that the thread sizing is that of a british/iso style bottom bracket (1.370" X 24 tpi)?
    Not necessarily. For example, Swiss-threaded bikes also have left-hand threading on the fixed cup, but the diameter and pitch are the same as French. A bike shop once almost destroyed the frame of our tandem by making the wrong guess about French vs. Swiss threading.

    What make is the bike?

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    heres the head badge. i'm thinking it was made by some department store in the 60s/70s.



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