Help needed: gap between lower headset cup and fork

Discussion in 'Bicycle Mechanics and Repairs' started by Torquewrench, 3 Feb 2018.

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  1. Torquewrench

    Torquewrench Member

    Location:
    UK
    Hi all! I am trying to build my first custom bike, based on Specialized Diverge frame (2015?).
    Bearings are original, all good, I don't see a physical difference between them so not sure which one suppose to go as upper/lower one. (all I could find is that for Specialized Allez lower and upper bearing type is the same, probably silly but I simply assume it should be he same for diverge?)
    But tried both ways and when I fit forks there appears a small gap between lower headset cup and fork.
    I know it shouldn't be like that because I saw same model bike the other day and it sits very evenly.

    What am I doing wrong or what am I missing? Any advice appreciated!
     

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  2. If there’s a gap there, the crown race is the problem. You may not need the crown race with the replacement head set you have, as the bottom bearing cup and race are integrated ( called a semi integrated ). I’m guessing the original one was a separate bearing cup and race design. So make sure you haven’t got a crown race you don’t need, sitting on top of the forks.
     
    Last edited: 3 Feb 2018
  3. Tangoup51

    Tangoup51 Well-Known Member

    @Torquewrench Yes, both upper & lower bearings with your headset are identical.

    If the bearings are original to that frame & so is the fork, then you have no worries. - Make sure you're preloading the headset properly, I find that sometimes you have to over-tighten the headset slightly after re-installing bearings to properly seat them and compress things, afterward you can loosen it and pre-load the bearings as you would for riding.

    - Keep an eye on that gap while you tighten the headset also.
     
  4. OP
    OP
    Torquewrench

    Torquewrench Member

    Location:
    UK
    Thanks guys! really appreciated your answers!
    when I got a frame - it came with the forks, those two bearings, a little plastic centering collar and stem top cap - so I thought I'm sorted with the headset.
    Crown race - do you mean this part? it is pretty solid on the fork and seems really tightly fit.

    I did everything like in this video, except I don't have the thin aluminium washer which was put on top of the collar in the video.
    I wouldn't mind the little gap there, but when the top headset cup is tightened you can feel a bit of the movement between forks and frame when front brakes are pressed and bike pushed forward. I'm tightening the headset top cap pretty solidly and wouldn't go further as might damage it?
     

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  5. It’s diificult to see from the photo. But some forks / steerers are ‘crown race less’ internal set ups. I’m not familiar with your bike, so I don’t know for sure. I know that I have a bike with an internal headset, and I replaced the headset with one I bought on line, I put the crown race ( supplied with the replacement, but not present on the original) on, put the forks back in, then noticed a gap, like the one you are describing. It turned out that the forks were ‘race less’ and dispensing with the crown race solved the issue. I had to get a different bottom bearing, from the one which was supplied though. I had words with the company who supplied the wrong one as well:laugh:. It’s a confusing old game the headset thing, not helped by a maze of different standards and designs.
     
    Last edited: 3 Feb 2018
  6. gazza1286

    gazza1286 Active Member

    Comparing the your photo of the crown race to others online appears to suggest that the one on your forks isn't fully seated.
     
    Last edited: 3 Feb 2018
  7. Pale Rider

    Pale Rider Guru

    The bevel on the bearing may be the wrong angle, meaning it doesn't sit fully in the frame.

    From what I can gather, this is a well-known problem when replacing bearings in tapered headsets, but it may apply in this case as well.
     
    Slick likes this.
  8. spiderman2

    spiderman2 Well-Known Member

    Location:
    Harrow
    Thats what I had on my specialized bike .the bearing I bought had an angle of 60 and should have been 45 .
     
    Racing roadkill likes this.
  9. That’s the most likely answer. It is the wrong angled bottom bearing for the crown race.
     
  10. OP
    OP
    Torquewrench

    Torquewrench Member

    Location:
    UK
    interesting about the angle! could be he case but I have no clue what angle bearings I have and what are required for this frame. please have a look into these pics, maybe will give a clue? in my opinion they sit nicely and match the places they need to be inserted, but maybe am wrong?
     

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  11. gazza1286

    gazza1286 Active Member

    If you just place the lower bearing itself on the crown race you should be able to see/feel whether the mating faces match. If they do, there will be no slippage or rocking at all.
     
  12. OP
    OP
    Torquewrench

    Torquewrench Member

    Location:
    UK
    just found out on the bearing hardly visible notice - 45 degrees (whole - PT-R418 (Ø41.8X8X45°).

    seems to be sitting solidly, no rocking whatsoever:
     

    Attached Files:

  13. Tangoup51

    Tangoup51 Well-Known Member

    I'm sorry have I missed something here? I can't help but feel like things are being wildly overthought.


    IF those are the bearings provided with the frame originally, the angles will be correct.

    Are you being overly cautious? are you being afraid? how much force are you really putting in to that headset in order to tighten it up? I've made the mistake of being too wimpy with my headset because I was afraid it'd break everything if I over tighten things, - but the reality is it's all very strong thick materials that you won't have a cat in hells chance of breaking with an allen key.

    Put everything back together and make sure you're preloading it correctly, i,e, theres spacers above the fork steerer tube so the top-cap can push down on the spacers, etc,

    and as you're tightening it, watch that gap. It should start to continually disappear as you tighten your headset, even when it gets stiffer and stiffer it should continue to go smaller.

    - here's a final tip.

    If you have tightened it up firmly enough, to which the handlebars will not turn freely, and YET there is STILL play (forward and back) Then there is something majorly wrong.

    If that's not the case and you can manage to get it with No play and Quiet, Free turning handlebars that is a completely fine headset. cutme2.PNG edit - That's a diverge sport 2015, that's quite a gap. Maybe the bike you originally saw with the flush head had the wrong angled bearings? :laugh::laugh:
     
  14. Slick

    Slick Veteran

    I just replaced the bearings in mine and glad the exact same gap. It turned out, as you describe, internal shoulder was a different angle. Guy in the LBS bodged together a repair by grinding down the plastic compression ring. I haven't ridden the bike since.
     
  15. spiderman2

    spiderman2 Well-Known Member

    Location:
    Harrow
    The only place I could get the correct bearing was from the Specialized shop,I think they said the bearings are machined for their frames.
     
    Racing roadkill likes this.
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