Headset comes loose after ~ 30 mins on roughish terrain

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Headset comes loose after ~ 30 mins on roughish terrain
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flag Steventux
Posted: Jul 26, 2018 at 14:14 Quote
I know this is an often asked question. I know because I've read most of the internet on the subject but the problem persists.
Capra CF 2016, Lyrik forks, RaceFace Atlas stem.
Newish headset bearings, though the problem was present prior to replacing them.

I started getting vibrations about a year after buying the bike. The normal thing, a light rattle through the bars, that feeling of something slightly loose or clonking, very subtle and at first hard to pinpoint.

Loosened the stem, pinched up the star nut to re-load the bearings, not too tight, re-torqued the stem to spec, problem gone.
A few months later same problem.
Serviced the bearings this time, they were in "British Winter" condition so I bought replacements as I could see the originals were close to farked.

Though I didn't keep an accurate spreadsheet, it seemed like the intervals between doing the headset preload dance as above were shorter.

New bearings installed, I noted the new top bearing isn't a tight fit into the frame, slight back-to-front (or should that be front-to-back Big Grin ) movement, it's a carbon bearing facing in the frame, but it's tapered so after preloading the bearing
and torquing the stem, it feels fine... for a while.

I only really need to ride a vaguely rooty or rocky trail and the headset comes loose, only very slightly but it's not a nice feeling.

If I sit the bike upside down and milk the goat (sit on the bb, feet on grips and push and pull on the forks) I can see and feel the headset movement. Once re-tightened I can't feel or see the same.

Other things I've tried:

- New star nut, fitted with a proper tool, not my usual bodge.
- Fork service. Seemed like the time was right and I wondered if it was some damper 'clonk'.
- Assembly paste, cleaned the stem and fork steerer with brake cleaner before applying. Is my stem slipping? I still wonder, though why it took over a year to start doing this makes me wonder (I've replaced stem bolts for fear of breaking one by going to max torque.)
- Headset bearing shim. A beercan shim to take the movement out of the top bearing. It's snug but makes no difference ultimately.
- A couple of thin spacers below the stem 0.5mm incase something wasn't right in the spacer stack, unlikely as everything tightens as it should and works well for a while.

I suspect the stem is sliding up the fork slightly, or possibly and far worse the headset cups have a crack somewhere (I've cleaned the frame several times to examine and can't see anything bad).

Anyone had a serial loosening problem with their headset?
Any carbon frame owners had similar? I've got BMXs that rattle less than this thing and need less maintenance.
Any recommendations for a choker of a stem? It seems like the cheapest test for whether it's loosing its grip...
flag Hammer48
Posted: Jul 26, 2018 at 15:14 Quote
Are you using carbon specific assembly paste on the steerer tube. ?
flag Steventux
Posted: Jul 27, 2018 at 2:27 Quote
Hammer48 wrote:
Are you using carbon specific assembly paste on the steerer tube. ?

Yeah, though the steerer and stem aren't carbon, so that's sub-optimal. I assumed the fine grit in the paste 'dug in' to the surfaces you were clamping together and made for more abrasive grip. I'm not a mechanical engineer evidently.

Looks like the Park Tool paste is Alloy/Carbon oriented http://www.chainreactioncycles.com/park-tool-supergrip-carbon-alloy-assembly-compound/rp-prod149819 admittedly I went for a cheaper 'carbon assembly' paste so this might be worth a go.
flag lepak1corner
Posted: Jul 27, 2018 at 2:56 Quote
at times, it's the stem. the pinch bolts ain't pinching the steerer tube enough. ever tried swapping to another stem to compare?
flag Steventux
Posted: Jul 27, 2018 at 3:44 Quote
lepak1corner wrote:
at times, it's the stem. the pinch bolts ain't pinching the steerer tube enough. ever tried swapping to another stem to compare?

I think this is a sensible move. I'd ideally like to find a #fullenduro 50mm stem with a healthy clamping surface.
Any recommendations?
flag riderseventy7
Posted: Jul 27, 2018 at 5:09 Quote
How far below the top of the headset spacers is the top of the steerer tube?
If theres not enough gap the top cap will hit the steerer tube and won't properly tighten down on the spacers, which then fails to preload the headset bearings. Take the top cap off and check for marks/scratches from the steerer underneath it. If that's what you find the simple solution is to put a spacer that's a few millimetres thicker over the steerer.
flag Steventux
Posted: Jul 27, 2018 at 5:30 Quote
riderseventy7 wrote:
How far below the top of the headset spacers is the top of the steerer tube?
If theres not enough gap the top cap will hit the steerer tube and won't properly tighten down on the spacers, which then fails to preload the headset bearings. Take the top cap off and check for marks/scratches from the steerer underneath it. If that's what you find the simple solution is to put a spacer that's a few millimetres thicker over the steerer.

It's a good 2mm, looks like they did it right at the factory.

I've also suspected the stack height might be a problem and added a 0.5mm shim to the spacer stack. I've also got a 2mm spacer which would probably prove the point better. The thing is when the spacer stack is wrong it's usually evident as soon as you tighten the star nut and stem, I can have anything from 10-30 mins of blissful riding before the symptoms return, usually after a jump, barrelling over roots or a rocky chute. I'll add the 2mm spacer to rule it out though, it's a possibility.
flag Hammer48
Posted: Jul 27, 2018 at 16:00 Quote
Steventux wrote:
Hammer48 wrote:
Are you using carbon specific assembly paste on the steerer tube. ?

Yeah, though the steerer and stem aren't carbon, so that's sub-optimal. I assumed the fine grit in the paste 'dug in' to the surfaces you were clamping together and made for more abrasive grip. I'm not a mechanical engineer evidently.

Looks like the Park Tool paste is Alloy/Carbon oriented http://www.chainreactioncycles.com/park-tool-supergrip-carbon-alloy-assembly-compound/rp-prod149819 admittedly I went for a cheaper 'carbon assembly' paste so this might be worth a go.

Looking back, I have no idea why I asked if he used carbon paste..Brain fart for sure, sorry.
flag Steventux
Posted: Jul 31, 2018 at 11:39 Quote
schralpknobslikecornonthecob wrote:
wrong crown race bro WHAM problem solved if you know what i mean

@schralpknobslikecornonthecob I've no idea what you mean. It's the same crown race as came with the fork. The issue was present before and after replacing the headset so it's not a bearing-to-crown-race mismatch.
flag gotohe11carolina
FL
Posted: Jul 31, 2018 at 20:51 Quote
In the interest of trying the simple, cheap stuff first have you tried a new or different stem? Do you have the wedge collar that holds the steerer tube straight in the top bearing? If you have and the problem persists I'd say you have an issue with the frame. If the head tube has a small crack that allows play you will be able to create leverage with the fork and move the stem. Hope it's the cheap stuff!
flag lepak1corner
Posted: Jul 31, 2018 at 20:54 Quote
does the Capra use a semi or integrated headset cup? Brand?

As for reliable stem with healthy clamp area, it depends. Any stem with M5 x 2 bolts with 35-40mm stack works for me tho. You might wanna check Deity Cavity.
flag Steventux
Posted: Aug 1, 2018 at 2:36 Quote
It's a carbon cup, and part of the frame, it's not removable, I guess that's 'integrated'.
Had the bike upside down and testing the play last night. The only play I could feel was in the fork legs (ie the bushings).
This is confusing.
As per all the sound advice I've had here, I'm replacing the stem as a test, I'm also measuring the stem position against the top of the steerer tube with a digital vernier gauge (plus a score mark just like granny used to do).
I wonder given the nature of the problem if @gotohe11carolina isn't right though. A crack would mean everything feels tight then loose under force.
flag lepak1corner
Posted: Aug 1, 2018 at 3:11 Quote
Steventux wrote:
It's a carbon cup, and part of the frame, it's not removable, I guess that's 'integrated'.
Had the bike upside down and testing the play last night. The only play I could feel was in the fork legs (ie the bushings).
This is confusing.
As per all the sound advice I've had here, I'm replacing the stem as a test, I'm also measuring the stem position against the top of the steerer tube with a digital vernier gauge (plus a score mark just like granny used to do).
I wonder given the nature of the problem if @gotohe11carolina isn't right though. A crack would mean everything feels tight then loose under force.

Integrated headset cups have always had this issue. There is bound to have bearing fit tolerance issue, noticeably the top(shallow fit) . Did you buy the same bearing dimension for replacement, inner/outer diameter, chamfer angle?
flag Steventux
Posted: Aug 1, 2018 at 3:21 Quote
lepak1corner wrote:
Steventux wrote:
It's a carbon cup, and part of the frame, it's not removable, I guess that's 'integrated'.
Had the bike upside down and testing the play last night. The only play I could feel was in the fork legs (ie the bushings).
This is confusing.
As per all the sound advice I've had here, I'm replacing the stem as a test, I'm also measuring the stem position against the top of the steerer tube with a digital vernier gauge (plus a score mark just like granny used to do).
I wonder given the nature of the problem if @gotohe11carolina isn't right though. A crack would mean everything feels tight then loose under force.

Integrated headset cups have always had this issue. There is bound to have bearing fit tolerance issue, noticeably the top(shallow fit) . Did you buy the same bearing dimension for replacement, inner/outer diameter, chamfer angle?

I thought I did yes, it was listed as a Capra CF replacement here: https://www.kineticbikebearings.com/ai42-ai52.html. The top bearing does have some front-to-back play which I've eliminated with a beercan shim. I wonder if this bodge is not enough though. I will measure up the integrated cup to see if it has any deformation as it seems like either the bearing or the cup is somehow very minimally eliptical. To the shed!
flag lepak1corner
Posted: Aug 1, 2018 at 3:33 Quote
Steventux wrote:
I thought I did yes, it was listed as a Capra CF replacement here: https://www.kineticbikebearings.com/ai42-ai52.html. The top bearing does have some front-to-back play which I've eliminated with a beercan shim. I wonder if this bodge is not enough though. To the shed!

Right on! Some gap fillers maybe?
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