Old style cup and cone bottom brackets.

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  • Old style cup and cone bottom brackets.
  • PeterPoddy
    Member

    There are two left hand (reverse) threads on a bike

    The left hand pedal
    BUT the right hand BB thread!

    Does that answer the question?

    PeterPoddy
    Member

    ….unless its an Italian thread BB that is. But it’s probably not. 🙂

    Premier Icon paul4stones
    Subscriber

    Won’t be Italian. So the non-drive is a normal RH thread and therefore the lock ring unscrews normally? Lefty loosy?
    So the action of the cracks turning may loosen the cup? Or it doesn’t because of that trepination effect of ball bearings?

    Thanks

    PeterPoddy
    Member

    So the action of the cracks turning may loosen the cup?

    No. There’s some bizarre mechanical reason it’s the way it is, but it’ll tighten the cup if anything. I can’t explain why but its DA TRUUF! 🙂

    Premier Icon paul4stones
    Subscriber

    I think that’s the ball bearing thing – must check on Sheldon!

    Premier Icon paul4stones
    Subscriber

    Just before I attack it. The non-drive is a LH thread I assume and so does the lock ring undo the ‘wrong’ way too? ie turn to the right to undo?

    Thanks

    Premier Icon Onzadog
    Subscriber

    To my mind, with the preload cap set up, HTII is crying out for a cup and cone bottom bracket. Imagine the size of the balls.

    shermer75
    Member

    because of that trepination effect of ball bearings?

    Is that where the ball bearings make a small hole in your skull?

    IGMC

    bencooper
    Member

    So the action of the cracks turning may loosen the cup? Or it doesn’t because of that trepination effect of ball bearings?

    It’s because, while the cranks might be turning anticlockwise (looking from the left), the bearings which actually touch the cup are rotating clockwise – hence tightening the cup into the frame.

    Premier Icon paul4stones
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    Hole in skull is trephination I think, using a trephine. 😉

    Premier Icon BigJohn
    Subscriber

    I would put a hole in my skull with trepidation.

    Premier Icon Onzadog
    Subscriber

    Think of the axle as a geared wheel and the bearings as another and the cup as another. Then makes perfect sense why it’s that way around.

    mickolas
    Member

    ‘trepination’! Every day’s a school day. 🙂

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