knocking

Discussion in 'Cycling Equipment' started by Michael, Dec 1, 2003.

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  1. Michael

    Michael Guest

    This is my third post on a persistent problem I'm having. To summarize:

    Post 1: Couldn't tighten headset fully. Turned out the steerer nut was too high or had slipped up to
    the top cap. Fixed by LBS. Post 2: I thought the steerer nut (which I called a star-fangled nut) was
    still slipping in the carbon steerer. Turns out (as many people noted) it's actually a wedge-type
    nut, and in fact it hadn't slipped.

    Here's the problem - when I do the normal loose-headset test (hold the front brake and rock the bike
    forwards and backwards), there's a knocking sound. Sounds just like if the headset is loose and the
    steerer is moving within the headset/headtube. Can't tell exactly where it's coming from except that
    it's along the fork, somewhere between the hub and stem.

    The LBS insists the headset is properly tight, and as far as I can tell it is. There's no movement
    between the adjustable race and the upper head-tube race when I put my finger where they meet while
    rocking the bike. Same on the bottom part of the headset.

    The LBS couldn't figure out the source of the knock, and gave up. Any ideas?

    Specs: new Litespeed Tuscany ti frame, Cane Creek S2 headset, Litespeed carbon disc & canti fork
    with carbon steerer, Avid mechanical disc brakes, Hope XC disc hubs.

    Thanks, Michael
     
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  2. Dan Brussee

    Dan Brussee Guest

    On 1 Dec 2003 09:10:50 -0800, [email protected] (Michael) wrote:

    >This is my third post on a persistent problem I'm having. To summarize:
    >
    >Post 1: Couldn't tighten headset fully. Turned out the steerer nut was too high or had slipped up
    >to the top cap. Fixed by LBS. Post 2: I thought the steerer nut (which I called a star-fangled nut)
    >was still slipping in the carbon steerer. Turns out (as many people noted) it's actually a
    >wedge-type nut, and in fact it hadn't slipped.
    >
    >Here's the problem - when I do the normal loose-headset test (hold the front brake and rock the
    >bike forwards and backwards), there's a knocking sound. Sounds just like if the headset is loose
    >and the steerer is moving within the headset/headtube. Can't tell exactly where it's coming from
    >except that it's along the fork, somewhere between the hub and stem.
    >
    >The LBS insists the headset is properly tight, and as far as I can tell it is. There's no movement
    >between the adjustable race and the upper head-tube race when I put my finger where they meet while
    >rocking the bike. Same on the bottom part of the headset.
    >
    >The LBS couldn't figure out the source of the knock, and gave up. Any ideas?
    >
    >Specs: new Litespeed Tuscany ti frame, Cane Creek S2 headset, Litespeed carbon disc & canti fork
    >with carbon steerer, Avid mechanical disc brakes, Hope XC disc hubs.
    >

    Skewer tight? Brakes mounted tight to fork? Disk mounted tight to hub? Disk pads mounted correctly?
    Stem tight? Handlebars tight? Hub bearings adjusted correctly?
     
  3. Jobst Brandt

    Jobst Brandt Guest

    Michael Press writes:

    > This is my third post on a persistent problem I'm having. To summarize:

    > Here's the problem - when I do the normal loose-headset test (hold the front brake and rock the
    > bike forwards and backwards), there's a knocking sound. Sounds just like if the headset is loose
    > and the steerer is moving within the headset/headtube. Can't tell exactly where it's coming from
    > except that it's along the fork, somewhere between the hub and stem.

    The trouble with this test is that it wraps up other loosenesses with head bearing adjustment. Try
    the bounce test whereby you raise the front end of the bicycle by holding the stem at the steertube
    and bouncing it on the ground. This should give a clear chattering noise that cannot come from a
    loose brake caliper or loose wheel skewer. It can excite a loose wheel bearing but that would need
    to be so loose that you can feel it by wiggling the tire side to side.

    > The LBS insists the headset is properly tight, and as far as I can tell it is. There's no movement
    > between the adjustable race and the upper head-tube race when I put my finger where they meet
    > while rocking the bike. Same on the bottom part of the headset.

    I think you are looking in the wrong place for the slop. Have you checked the other places that have
    been suggested? Why can't the guys at the bicycle shop find this when you show it to them?

    > The LBS couldn't figure out the source of the knock, and gave up. Any ideas?

    I think you don't have a good bicycle shop. If they can't find this then maybe they also don't know
    how to adjust the head bearing. It's hard to see from here but it makes me wonder.

    Jobst Brandt [email protected]
     
  4. A Muzi

    A Muzi Guest

    Michael wrote:

    > This is my third post on a persistent problem I'm having. To summarize:
    >
    > Post 1: Couldn't tighten headset fully. Turned out the steerer nut was too high or had slipped up
    > to the top cap. Fixed by LBS. Post 2: I thought the steerer nut (which I called a star-fangled
    > nut) was still slipping in the carbon steerer. Turns out (as many people noted) it's actually a
    > wedge-type nut, and in fact it hadn't slipped.
    >
    > Here's the problem - when I do the normal loose-headset test (hold the front brake and rock the
    > bike forwards and backwards), there's a knocking sound. Sounds just like if the headset is loose
    > and the steerer is moving within the headset/headtube. Can't tell exactly where it's coming from
    > except that it's along the fork, somewhere between the hub and stem.
    >
    > The LBS insists the headset is properly tight, and as far as I can tell it is. There's no movement
    > between the adjustable race and the upper head-tube race when I put my finger where they meet
    > while rocking the bike. Same on the bottom part of the headset.
    >
    > The LBS couldn't figure out the source of the knock, and gave up. Any ideas?
    >
    > Specs: new Litespeed Tuscany ti frame, Cane Creek S2 headset, Litespeed carbon disc & canti fork
    > with carbon steerer, Avid mechanical disc brakes, Hope XC disc hubs.

    Those symptoms would be consistent with a seal misplaced, some component of the headset upside down
    or omission/reversal of the conical centering ring.

    --
    Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
     
  5. Pete Biggs

    Pete Biggs Guest

    Michael wrote:
    > Here's the problem - when I do the normal loose-headset test (hold the front brake and rock the
    > bike forwards and backwards), there's a knocking sound. Sounds just like if the headset is loose
    > and the steerer is moving within the headset/headtube. Can't tell exactly where it's coming from
    > except that it's along the fork, somewhere between the hub and stem.

    It could be from a loose brake or suspension system if forks are suspension type, but it may well be
    a loose headset despite what the shop say. Maybe they haven't tested it as vigourously.

    The drop test can help - but I find, with non-sus forks, the rocking-with-brake-on test can detect a
    smaller amount of play when bike is rocked HARD with brake on HARD.

    > The LBS insists the headset is properly tight, and as far as I can tell it is. There's no movement
    > between the adjustable race and the upper head-tube race when I put my finger where they meet
    > while rocking the bike. Same on the bottom part of the headset.

    A small amount of play won't always be noticeable in that way.

    ~PB
     
  6. Eric M

    Eric M Guest

    In article <[email protected]>, Michael <[email protected]> wrote:

    >Here's the problem - when I do the normal loose-headset test (hold the front brake and rock the
    >bike forwards and backwards), there's a knocking sound. Sounds just like if the headset is loose
    >and the steerer is moving within the headset/headtube. Can't tell exactly where it's coming from
    >except that it's along the fork, somewhere between the hub and stem.
    >
    >The LBS insists the headset is properly tight, and as far as I can tell it is. There's no movement
    >between the adjustable race and the upper head-tube race when I put my finger where they meet while
    >rocking the bike. Same on the bottom part of the headset.
    >
    >The LBS couldn't figure out the source of the knock, and gave up. Any ideas?
    >
    >Specs: new Litespeed Tuscany ti frame, Cane Creek S2 headset, Litespeed carbon disc & canti fork
    >with carbon steerer, Avid mechanical disc brakes, Hope XC disc hubs.

    Pads moving back and forth in the caliper. Disc moving on its mounts (if it's a floating disc).

    Eric
     
  7. Michael wrote:

    Piece of metal or stone in your rims. Something may have been dropped inside while lacing the wheel.

    --
    Perre

    You have to be smarter than a robot to reply.
     
  8. Werehatrack

    Werehatrack Guest

    On 1 Dec 2003 09:10:50 -0800, [email protected] (Michael) may have said:

    >The LBS couldn't figure out the source of the knock, and gave up. Any ideas?
    >
    >Specs: new Litespeed Tuscany ti frame, Cane Creek S2 headset, Litespeed carbon disc & canti fork
    >with carbon steerer, Avid mechanical disc brakes, Hope XC disc hubs.

    There is a common problem in automotive disc brakes in which such a knock is produced by motion of
    the pads in the caliper. This is the reason for the presence of a small (usually leaf-type) spring
    somewhere in the assembly which keeps the pad loaded against the side of the pad recess, pushed
    against the caliper body in the direction of rotation. As long as the brakes are applied while
    rolling forward, the radial slop in the pad has already been taken up, and there's no knock. Apply
    the brakes suddenly while rolling back, and there's a knock. I believe this may be what's happening
    with your setup. If so, I wouldn't worry about it.

    --
    My email address is antispammed; pull WEEDS if replying via e-mail. Yes, I have a killfile. If I
    don't respond to something, it's also possible that I'm busy. Words processed in a facility that
    contains nuts.
     
  9. Richard Chan

    Richard Chan Guest

    [email protected] (Michael) wrote in message
    news:<[email protected]>...
    >
    > The LBS insists the headset is properly tight, and as far as I can tell it is. There's no movement
    > between the adjustable race and the upper head-tube race when I put my finger where they meet
    > while rocking the bike. Same on the bottom part of the headset.
    >
    > The LBS couldn't figure out the source of the knock, and gave up. Any ideas?
    >
    > Specs: new Litespeed Tuscany ti frame, Cane Creek S2 headset, Litespeed carbon disc & canti fork
    > with carbon steerer, Avid mechanical disc brakes, Hope XC disc hubs.

    Now this I do have actual experience (Cane Creek S2 Pro). Is there a gap between the crown race and
    the bottom cartridge bearing? If yes, mail me privately.
     
  10. Jim Beam

    Jim Beam Guest

    > There is a common problem in automotive disc brakes in which such a knock is produced by motion of
    > the pads in the caliper. This is the reason for the presence of a small (usually leaf-type) spring
    > somewhere in the assembly which keeps the pad loaded against the side of the pad recess, pushed
    > against the caliper body in the direction of rotation. As long as the brakes are applied while
    > rolling forward, the radial slop in the pad has already been taken up, and there's no knock. Apply
    > the brakes suddenly while rolling back, and there's a knock. I believe this may be what's
    > happening with your setup. If so, I wouldn't worry about it.

    good similie - i think that's exactly right.
     
  11. Richard Chan

    Richard Chan Guest

    A Muzi <[email protected]> wrote in message news:<[email protected]>...

    > Those symptoms would be consistent with a seal misplaced, some component of the headset upside
    > down or omission/reversal of the conical centering ring.

    I have this same headset (S2 Pro). If you have a gap between the crown race and the bottom cartrige
    bearing, call Cane Creek. They will send you a new bottom assembly for free. There was a
    mismatch/design issue with the bearing/race such that you can not close the gap.
     
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