Such a seemingly simple issue is now doing my head in! In short my headset keeps loosening.

Longer version:
Got a carbon frame (road) with integrated headset (no cups at all), carbon fork with carbon steerer (no crown race), new bearings (in case it was them causing the issue), alu stem (nothing exciting). Doesn’t seem to matter what I do, it keeps loosening off.

Currently I’ve got carbon assembly paste in the stem-steerer interface, and the stem bolts have been over-torqued. It started to loosen off in 3 rides. Next will be just to tighten in the way I would with an mtb setup and ignore the torque values.

Anyone got any thoughts about what could be the issue here? Stem clamp perhaps?

Weird there is no crown race, are you sure it should be like that?

Weird there is no crown race, are you sure it should be like that?

Got a photo of the fork? Some are like that, but I thought it was pretty rare.

Could be the stem though, I had an on-one stem that wasn’t right which manifested as a headset that wouldn’t stay tight. I think it was on the piss so it tightened as the bars turned, so each corner was loosening the headset slightly.

Is there an expanding bung inside the steerer? Is that done up well enough to hold everything in place? You didn’t seem to mention that bit which is obviously different to having a star nut like you might on a mtb set up…

I’ve had problems with this too:
Clean off the stem / steerer (I used iso-propyl alcohol from the local pharmacy)
I’m trying Motorex “sticky” paste. I found that the gritty-types didn’t work for me
Pre-load the stem top cap properly
Torque to spec

If it’s been like this for a while have a look at the steerer at the level of the headset upper race, the split compression ring can wear a groove around the steerer

Yeah fork is meant to be like that (Giant TCR) but I shat myself the first time I saw it!

Good point about the bung, it’s Giants big overdrive thing. Don’t think it’s to blame as it’s still sitting flush and doesn’t seem to have ever budged. Also, it’s the stem that’s taking the force when everything’s tightened anyway, so it shouldn’t come into play.

Timba, that’s what I’ve been doing but with Finish Line paste (gritty) instead. No issues with the top race or anywhere on the steerer

😕

Also, it’s the stem that’s taking the force when everything’s tightened anyway, so it shouldn’t come into play.

Indeed however if the bung isn’t secure then (IME) any preloading can be lost regardless of how tight you’ve got the stem attached to a potentially arbitrary bit of the steerer.

Lol, my mate has this issue on his 2008 TCR!

I would suggest doing all the above, but also putting a thin spacer or two on top of the compression ring, just to make sure it’s not the headset top cap bottoming out on the frame/bearings.

It does only have 1 of those thin spacers on the go, not a bad idea to shove a couple extra in. Of course I can’t find anywhere online that sells them though, will need to venture to the shop

I would suggest doing all the above, but also putting a thin spacer or two on top of the compression ring, just to make sure it’s not the headset top cap bottoming out on the frame/bearings.

Hope headset shims are available online. If the headset is pre-loading correctly without play then shims shouldn’t be necessary, you’ll know if the top bearing cover is bottoming out because the steering will bind.
Raise the top cover unnecessarily and you’ll reduce the seal at the headtube

Steerer groove pic. Not mine, but check the compression ring for sharp edges, especially on the split ends

Do Hope do them for 1 1/4″ steerers though? Only seeing 1 1/8th and 1.5 atm

Ah! LBS then. If that fails you can get 30 and 32mm ID bearing shim washers that might work

“bearing shim washers” thats the name I’ve been looking for! Found some online thanks, but might as well have a chat with the LBS first (incase it does go down the warranty route)