Seat collar tightening

Discussion in 'UK and Europe' started by Paul, Jun 22, 2003.

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  1. Paul

    Paul Guest

    I was wondering whether it is possible to damage the seat tube of a aluminium frame by over
    tightening a quick release seat collar, or in other words is it possible to over tighten a QR seat
    collar and how do you tell if you have? What constitutes 'normal' pressure for closing a QR lever?

    When I changed the bolt on my seat collar for a QR I noticed a bit of sinking in the post over every
    few rides. The guys in a couple of bike shops that I've talked to about this have simply wound the
    QR tighter by a turn or two until the problem is solved but the result is that it now takes quite a
    bit of pressure to close the QR lever and, I imagine, that this must put a fair amount of force onto
    the tube and flex it a fair bit (I thought aluminium wasn't good at being flexed).

    There is approx. a 4mm gap between the edges of the slot in the seat tube with the collar fully
    closed. The seat tube iteself is 31.2 and the post is
    26.6 and shimmed in correctly.

    Thanks for any thoughts, Kind Regards, Paul.
     
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  2. [email protected] schreef ...
    > I was wondering whether it is possible to damage the seat tube of a aluminium frame by over
    > tightening a quick release seat collar, or in other words is it possible to over tighten a QR seat
    > collar and how do you tell if you have? What constitutes 'normal' pressure for closing a QR lever?
    >
    > When I changed the bolt on my seat collar for a QR I noticed a bit of sinking in the post over
    > every few rides. The guys in a couple of bike shops that I've talked to about this have simply
    > wound the QR tighter by a turn or two until the problem is solved but the result is that it now
    > takes quite a bit of pressure to close the QR lever and, I imagine, that this must put a fair
    > amount of force onto the tube and flex it a fair bit (I thought aluminium wasn't good at being
    > flexed).
    >
    > There is approx. a 4mm gap between the edges of the slot in the seat tube with the collar fully
    > closed. The seat tube iteself is 31.2 and the post is
    > 26.6 and shimmed in correctly.

    If you don't really need the QR, substitute the collar for a model with a bolt or even with two
    bolts over each other. The latter are found on tandems where the stoker can exert rather large
    torsional forces on the captain's seatpost.

    --
    Mvg, Marten
     
  3. Peter B

    Peter B Guest

    "Paul" <[email protected]> wrote in message news:[email protected]...
    > I was wondering whether it is possible to damage the seat tube of a aluminium frame by over
    > tightening a quick release seat collar, or in
    other
    > words is it possible to over tighten a QR seat collar and how do you tell
    if
    > you have? What constitutes 'normal' pressure for closing a QR lever?

    My post started slipping down after a couple of years. After repeatedly tightening it with the same
    result I eventually removed the plastic spacer that the cam rides in, it's been ok since. I think
    the plastic was just squashing a bit more after each tightening.

    Pete
     
  4. I don't have a QR but I do have an aluminium frame (Sakae-Ringko,
    a.k.a. "SR") and had great trouble with the seat post slowly sinking. One day I overdid the
    tightening and the bolt exploded! After that, I shimmed the post using brass shim (the
    thickest it would accept) and now all is good and stable.

    Philip Taylor
    --------
    Paul wrote:
    >
    > I was wondering whether it is possible to damage the seat tube of a aluminium frame by over
    > tightening a quick release seat collar, or in other words is it possible to over tighten a QR seat
    > collar and how do you tell if you have? What constitutes 'normal' pressure for closing a QR lever?
    >
    > When I changed the bolt on my seat collar for a QR I noticed a bit of sinking in the post over
    > every few rides. The guys in a couple of bike shops that I've talked to about this have simply
    > wound the QR tighter by a turn or two until the problem is solved but the result is that it now
    > takes quite a bit of pressure to close the QR lever and, I imagine, that this must put a fair
    > amount of force onto the tube and flex it a fair bit (I thought aluminium wasn't good at being
    > flexed).
    >
    > There is approx. a 4mm gap between the edges of the slot in the seat tube with the collar fully
    > closed. The seat tube iteself is 31.2 and the post is
    > 26.6 and shimmed in correctly.
     
  5. Arthur Clune

    Arthur Clune Guest

    Philip TAYLOR [PC87S-O/XP] <[email protected]> wrote:
    : I don't have a QR but I do have an aluminium frame (Sakae-Ringko,
    : a.k.a. "SR") and had great trouble with the seat post slowly sinking. One day I overdid the
    : tightening and the bolt exploded! After that, I shimmed the post using brass shim (the
    : thickest it would accept) and now all is good and stable.

    If you can fit shims in, your seat post is too small for the frame. Seat posts come in many, many,
    many different sizes. Only way to be sure is to use either a micrometer or a setpost measuring thing
    to get the size exactly.

    Arthur

    --
    Arthur Clune http://www.clune.org Power is delightful. Absolute power is absolutely delightful -
    Lord Lester
     
  6. Arthur Clune wrote:

    [snip]

    > If you can fit shims in, your seat post is too small for the frame. Seat posts come in many, many,
    > many different sizes. Only way to be sure is to use either a micrometer or a setpost measuring
    > thing to get the size exactly.

    In fact, both downtube & pillar were stamped, and the match was correct, but I think that the
    tightening had been overdone in the past so that there was no longer sufficient flexion ("give") in
    the downtube split section to clamp the post firmly. I very gently opened it up to accept thin shim,
    and then all was well.

    ** Phil
     
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