Should i have used Carbon Paste on headset bearing cup?

[-Matt]

So was getting some creaking from the head set area on my "22 Cube Stereo 160.

I took the forks off, and the lower bearing was very much expired, so knocked the cup out of the carbon frame, fitted a new bearing and knocked the cup back in.

I greased the cup with normal assembly grease.

But still getting creaking - especially on hard braking, or big hits/drops.

I also has a relatively small crash last week and the cup managed to spin in the frame - it has the block lock. And was surprisingly easy to spin back around with the bars.

Having a read, maybe i should have used Carbon assembly paste?

So should i have used Carbon assembly paste between the headset cup and frame?

Cheers

 

[mike_kelly]

Carbon paste is primarily used on carbon to prevent slipage, like a seat post. Since you had to tap out your bottom cup it was not loose and hence I think the answer is no.

 

[Stihldog]

I would be concerned that the assembly grease could contaminate the bearings. (The assembly grease that I have has a very fine grit in it and I’d is generally used for carbon bar and dropper post installation so that slightly less torque needs to be applied.

When reassembling the fork the stem bolt is generally torqued to 4-5nm. Make sure the star nut is not sliding then check for any play or creeks. Only after this procedure, tighten and align the bar and tighten the stem clamp to torquing specs.

If there continues to be issues with the bearing cup, your LBS may be able to help. Could be a frame fitment issue for the bearing cup.

 

[RipGroove]

My headset on my old '20 Cube Stereo 160 creaked, I fitted a new headset with carbon paste and it was silent afterwards with no issues. Granted I can't tell you if the paste alone fixed it because I put a new headset in as well but I can say the paste caused no issues.

 

[steve_sordy]

Carbon paste is primarily used on carbon to prevent slipage, like a seat post. ..............

I thought it was to increase grip* and therefore require less tightening torque.
Reduced torque is good for components that don't like being crushed, like carbon bars. Be aware that dropper seat posts come into that category because they are full of delicate components. Therefore, all my dropper posts are treated with carbon assembly paste, even on alloy frames.

Note* "increased grip" looks the same as "to prevent slippage", but the point is to achieve the required grip with reduced tightening torque.

 

[RustyIron]

So should i have used Carbon assembly paste between the headset cup and frame?

No. Absolutely not. Carbon assembly paste contains coarse grit that will abrade whatever surfaces it contacts. The "pocket" in your frame needs to be as precise as possible, and abrading it will create even more sloppiness.

 

[steve_sordy]

No. Absolutely not. Carbon assembly paste contains coarse grit that will abrade whatever surfaces it contacts. The "pocket" in your frame needs to be as precise as possible, and abrading it will create even more sloppiness.

Coarse grit? Are you sure? It is supposed to be a squashable crumb.

Edit: I have just googled it. Fenwicks use plastic microbeads (the sort of stuff I would expect). But Peaty uses "crushed volcano" ie pumice. The thought of pumice in there appalls me, but the blurb says that the whole idea is to immobilise the joint therefore no abrasion. Hmmm

Personally, I will avoid Peaty's product, because it has a component that is meant to be abrasive. I now must go check what's in my Finish-Line carbon assembly gel! ..... Hmmm, no data.

While I was looking, one comment I found was that for anyone concerned that the "bits" in the assembly paste/gel/whatever might scratch the components, they should consider that without it the components slipped and scratched themselves anyway!

Every day is a learning day!

 

[RustyIron]

Coarse grit? Are you sure? It is supposed to be a squashable crumb.

Yeah. I have Finish Line Fiber Grip. It will scratch up your components--it says so right on the label. On something that moves around a little, like a bearing and its mating surfaces, it will act like lapping paste.