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Eliminating fork wobble

pangolinpangolin Posts: 5,495
in Workshop


Fitted a new stem and bars and cannot seem to get the forks to stop wobbling entirely. Pic shows the spacer underneath extending about 1mm past the headtube, it goes between here and being completely flush (i.e. where it should be).

Fork has an expanding bung, this is flush with the top of the fork and done up tightly.

Top of the stem sits 5mm or so past the top of the fork, so has room to be pulled down.

I'm leaving the stem very loose and tightening the bolt on the topcap to snug it all together. Just doing this finger tight, any tighter and the bars start to have some resistance to turning as you'd expect.

But even with the bars very slightly harder to turn than I'd want, there is still fork wobble. Any ideas?
Genesis Croix de Fer
Cube Attain

Posts

  • pangolinpangolin Posts: 5,495
    edited May 2022
    There were a couple of discussions about this before on this bike but I think the consensus was people not tightening the expanding bung properly, which I've definitely done.

    https://forum.bikeradar.com/discussion/13074090/headset-not-tightening/p1
    https://forum.bikeradar.com/discussion/13074495/first-road-bike-cube-attain-gtc-pro-disc-2016/p9

    Should I try a star nut? Steerer is not carbon.
    Genesis Croix de Fer
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  • me-109me-109 Posts: 1,778
    edited May 2022
    Two possibilities on the bearing stack:
    - preload cone washer has taken a set that means it sits fully inside the top bearing with no preload; you could try prising open a little.
    - you are missing a washer between the preload cone washer and the underside of the bearing cover you picture as moving. That would prevent the cone washer being loaded correctly when you tighten the top cap.

    If the bearing stack is ok then check for movement of the bearing race in the frame, but if not doing it before your headset work it's pretty unlikely.
  • pangolinpangolin Posts: 5,495
    Thanks that's really helpful. It's this headset, is the pre cone washer the one that has a split in it? This was sitting on top and moving freely.

    https://www.bike-discount.de/en/cube-headset-fsa-orbit-c33-acb-1-1/8-1-1/4

    Not sure there was a washer between that and the bearing cover though so that could well be the issue.
    Genesis Croix de Fer
    Cube Attain
  • sungodsungod Posts: 15,573
    pangolin said:

    Thanks that's really helpful. It's this headset, is the pre cone washer the one that has a split in it? This was sitting on top and moving freely.

    https://www.bike-discount.de/en/cube-headset-fsa-orbit-c33-acb-1-1/8-1-1/4

    Not sure there was a washer between that and the bearing cover though so that could well be the issue.

    this is the fsa diagram (it says no.44e, but it's another name for c-33)
    https://shop.fullspeedahead.com/en/files/index/download/id/3f7b1c0dad67efbeaa97d29269189f3a528

    should help checking you have the right bits in there
    my bike - faster than god's and twice as shiny
  • MattFalleMattFalle Posts: 11,644
    This review goes on about it needing a spacer to sit properly - all ok with this on yours?

    and yup, you can use a star nut no worries if you like.


    .
    The camera down the willy isn't anything like as bad as it sounds.
  • pangolinpangolin Posts: 5,495
    Hmm. These are all the parts I was using on the top side of the headset.



    It works ok in this formation - wobble gone:



    I thought I was meant to replace the part with with the FSA logo with the doyenne bit 2nd from the left in the top pic. It certainly looked more correct like that!
    Genesis Croix de Fer
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  • me-109me-109 Posts: 1,778
    pangolin said:

    Thanks that's really helpful. It's this headset, is the pre cone washer the one that has a split in it? This was sitting on top and moving freely.

    https://www.bike-discount.de/en/cube-headset-fsa-orbit-c33-acb-1-1/8-1-1/4

    Not sure there was a washer between that and the bearing cover though so that could well be the issue.

    Aye, part 4 in the diagram @sungod linked. If it drops in and sits flush with the top it may be a bit tired. The other washer I'd expect is part 3 which you reckon could be missing. Just check its not stuck to the underside of the cap above.
  • pangolinpangolin Posts: 5,495
    edited May 2022
    me-109 said:

    pangolin said:

    Thanks that's really helpful. It's this headset, is the pre cone washer the one that has a split in it? This was sitting on top and moving freely.

    https://www.bike-discount.de/en/cube-headset-fsa-orbit-c33-acb-1-1/8-1-1/4

    Not sure there was a washer between that and the bearing cover though so that could well be the issue.

    Aye, part 4 in the diagram @sungod linked. If it drops in and sits flush with the top it may be a bit tired. The other washer I'd expect is part 3 which you reckon could be missing. Just check its not stuck to the underside of the cap above.
    Interesting, someone here says it may be bonded to the cone spacer, in which case I guess I'm stuck with that part?

    https://www.cyclechat.net/threads/fsa-ms100-seal.268949/
    Genesis Croix de Fer
    Cube Attain
  • i.bhamrai.bhamra Posts: 260
    You could try 1 or 2 microspacers under the Prime cone spacer?

    Something like this, can probably find a bunch of them for pennies on Ebay etc

    https://www.edinburghbicycle.com/fsa-micro-spacer
  • masjermasjer Posts: 2,124
    ^^This.
    me-109 said as much:- you are missing a washer between the preload cone washer and the underside of the bearing cover you picture as moving. That would prevent the cone washer being loaded correctly when you tighten the top cap.

    If you look at the pic of the FSA cover, it sits clear of the frame. The pic of the Prime one sits lower fouling the frame when preloaded.
  • pangolinpangolin Posts: 5,495
    Well it seems to be part of the FSA cover, tried some prying but short of breaking the thing it did not seem to be coming apart.
    Genesis Croix de Fer
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  • MattFalleMattFalle Posts: 11,644
    do you have to keepp tge cone cover? can you try another?

    mf has dumped them before with no dramas
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • pangolinpangolin Posts: 5,495
    MattFalle said:

    do you have to keepp tge cone cover? can you try another?

    mf has dumped them before with no dramas

    I think the issue is this headset combines the cover with the washer (parts 2 and 3 in the pdf linked by sungod upthread) - so if I ditch the cover I need another washer. Don't think I have one currently.
    Genesis Croix de Fer
    Cube Attain
  • MattFalleMattFalle Posts: 11,644
    darn.

    worth just libbing on another top cover just to try?

    takes 5 mins and may be the panacea to all evils.

    you know how randomnley all this stuff works out sometimes

    i dumped the cone Pina branded one off the Prince and just lobbed a flat one on and all worked fine straight out of the parrot.
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • veronese68veronese68 Posts: 26,289 Lives Here
    I once replaced an FSA cone type spacer with a flatter FSA one that had the thrust washer as part of it. I just asked in a bike shop if they had a flatter version of what I had and they rifled through their bucket of odds and sods for something. I returned with a packet of Jaffa Cakes for their trouble.
    Kinesis Pro6
    Marin Nail Trail
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