strange headset adjustment

Discussion in 'Cycling Equipment' started by Steve, Jun 12, 2003.

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  1. Steve

    Steve Guest

    Hi Everyone, I replaced the stem on my new mountain bike (ahead) and I noticed that the headset was
    a bit loose, so I torqued it according to mfg. spec (22 in-lbs) and tightened down the stem. When
    tightened down, the headset appears to become looser. I can hear this as well as see slight motion
    in the spacers above the headset. When I loosen the stem (without touching the preload cap) the play
    goes away. To get the headset to an acceptable adjustment, I need about twice the recommended
    preload. Adjusted in this fashion, there doesn't seem to be excessive friction, so I don't think
    it's too tight.

    Anyone ever seen this? could something be going on with the stem (change in geometry when
    tightened)? I'm tempted to just leave it, and toss the headset if it eats itself due to excessive
    preload. I've already checked the cap clearance, etc.

    Any sage advice would be appreciated.

    Thanks,

    Steve.
     
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  2. Gregr

    Gregr Guest

    On Fri, 13 Jun 2003 02:37:56 GMT, Steve <[email protected]> wrote:

    >Hi Everyone, I replaced the stem on my new mountain bike (ahead) and I noticed that the headset was
    >a bit loose, so I torqued it according to mfg. spec (22 in-lbs) and tightened down the stem. When
    >tightened down, the headset appears to become looser. I can hear this as well as see slight motion
    >in the spacers above the headset. When I loosen the stem (without touching the preload cap) the
    >play goes away. To get the headset to an acceptable adjustment, I need about twice the recommended
    >preload. Adjusted in this fashion, there doesn't seem to be excessive friction, so I don't think
    >it's too tight.
    >
    >Anyone ever seen this? could something be going on with the stem (change in geometry when
    >tightened)? I'm tempted to just leave it, and toss the headset if it eats itself due to excessive
    >preload. I've already checked the cap clearance, etc.
    >
    >Any sage advice would be appreciated.
    >
    >Thanks,
    >
    >Steve.

    This does not happen to be a welded aluminum stem?

    If you set the stem on a flat surface, you may see that the stem does not sit flat. You may notice
    that there is a difference at the "gap" that the pinch bolts tighten. This makes the headet load
    crooked when tightened.

    Common among "sale" welded aluminum stems (aka rejects). Whent they weld the stem together, the
    expansion and contraction due to the intense heat of welding distorts the material.

    You can take a file and make it flat again, but you also need to be sure to keep it square with the
    steerer tube. A little filing, a little checking, more filing...soon enough it will be good to go.

    G
     
  3. Steve

    Steve Guest

    GregR, Thanks, I suspected as much. The stem is an inexpensive forged weyless stem from supergo. If
    it's still too loose after the last adjustment I'll look into modifications.

    Thanks again,

    Steve.

    GregR wrote:
    > On Fri, 13 Jun 2003 02:37:56 GMT, Steve <[email protected]> wrote:
    >
    >
    >>Hi Everyone, I replaced the stem on my new mountain bike (ahead) and I noticed that the headset
    >>was a bit loose, so I torqued it according to mfg. spec (22 in-lbs) and tightened down the stem.
    >>When tightened down, the headset appears to become looser. I can hear this as well as see slight
    >>motion in the spacers above the headset. When I loosen the stem (without touching the preload cap)
    >>the play goes away. To get the headset to an acceptable adjustment, I need about twice the
    >>recommended preload. Adjusted in this fashion, there doesn't seem to be excessive friction, so I
    >>don't think it's too tight.
    >>
    >>Anyone ever seen this? could something be going on with the stem (change in geometry when
    >>tightened)? I'm tempted to just leave it, and toss the headset if it eats itself due to excessive
    >>preload. I've already checked the cap clearance, etc.
    >>
    >>Any sage advice would be appreciated.
    >>
    >>Thanks,
    >>
    >>Steve.
    >
    >
    > This does not happen to be a welded aluminum stem?
    >
    > If you set the stem on a flat surface, you may see that the stem does not sit flat. You may notice
    > that there is a difference at the "gap" that the pinch bolts tighten. This makes the headet load
    > crooked when tightened.
    >
    > Common among "sale" welded aluminum stems (aka rejects). Whent they weld the stem together, the
    > expansion and contraction due to the intense heat of welding distorts the material.
    >
    > You can take a file and make it flat again, but you also need to be sure to keep it square
    > with the steerer tube. A little filing, a little checking, more filing...soon enough it will
    > be good to go.
    >
    > G
    >
    >
    >
     
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