Mix and match Headset

Discussion in 'Cycling Equipment' started by Luke, Apr 29, 2004.

  1. Luke

    Luke Guest

    Swapping out forks on my Schwinn I discovered when removing
    the HS crown race of the old forks that it had been shimmed
    to provide a snug fit. (Considerate of my LBS to tell me
    this when they installed their HS.) A caliper reveals that
    the YST's crown race is 27mm while both the original and
    replacement forks have 26.4mm crown race seats. The shim
    itself appears to improvised from a beer can. Looks like
    Stella Artois. Good taste!

    Though I wasn't pleased to discover the arrangement, I
    confess the crown race fit was quite secure; it took effort
    to remove and obviously was pressed on with force. As it
    should be. Looks like the LBS wrench was familiar with the
    procedure.

    The headset is a threadless 1 inch YST HP250A. It has ball
    bearings in the upper cup and rollers in the lower. I didn't
    want to utilize the shimmed crown race setup with the new
    forks - partially because I really don't know how to press
    fit the shim/race combination onto the seat without mangling
    the delicate shim.

    So I reached into the parts box. There I had an old FSA
    Duron 1" threaded HS - also of an upper ball/lower roller
    configuration. The FSA employs a split collar that slides
    over the fork crown race seat. No press required. Two
    conical sleeves act as races and sandwich the roller bearing
    cage with the lower race sitting atop the split collar.

    It mimics the setup of the YST HS, with the exception that
    the YST's collar (previously referred to as crown race) is
    not split. But despite the collar being press fit onto a
    fork's crown race seat, it also forms the base of a conical
    race/ roller bearing sandwich like the FSA. (ie the rollers'
    lower conical race rests directly atop it.)

    Another point: Since the FSA employs a split collar I'm
    unsure whether it's specifically designed for a 26.4mm
    crown race seat (it initially was installed on such), a
    27mm seat or both.

    I initially contemplated replacing the lower cup assembly of
    the YST HS with that of the FSA. Aesthetically, it's not an
    issue that the HS employs cups of different makes. But I do
    want the result to be mechanically sound.

    But, first I thought to try this: Installing the FSA's split
    collar and using it conjunction with the YST's lower bearing
    cup assembly - sans it's own press fit collar. I reassembled
    the bike and set the HS preload. The bearings aren't
    binding, the forks turn freely and there's no play in the
    HS. But this isn't exactly a rigorous test of the soundness
    of the proposition.

    I haven't gone for an extended ride yet. Any comments
    before I do.

    Thank you Luke
     
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