"Slipping" headset

[bontie]

I have a Chorus integrated 1 1/8th headset on a De Rosa Team alu that just seems to to come loose after a few km of riding.
The plastic insert that slots in last before the cap seems to move slightly out of position resulting in play in the headset.

Any idea what cause this or how I can resolve?

TIA

[sungod]

it's normally the stem that maintains things in position

so if things are going loose it implies the stem is slipping, which is dangerous

not familiar with that bike, but normal adjustment is...

1 loosen top bolt

2 loosen stem

3 use top bolt to set correct preload on headset bearings

4 align and tighten stem

5 check for play, if there is play, go back to step 2

once the stem is tight, the top bolt and cap play no part other than filling the hole in the top of the steerer

[em3]

Here is some required reading on proper threadless headset adjustment.

http://www.parktool.com/blog/repair-hel ... et-service

In addition to suggestions already provided above, you need to check ur compression plug or starnut and make sure they are properly fixed in your steertube....the most likely sourse of said slipping.
EM3

[bontie]

Thanks guys, pretty much what I suspected.
It is a carbon steerer, but the bung is notin best of conditions, I bought the frame second hand - and knew this when I bought it.

Bontie

[ElChaba]

A couple of things to try...
Re the little plastic ring....Its purpose is to center the column in the headset. Assemble everything and press the ring down as firmly as possible by hand. Take the final piece that goes on top of it an put it into position UPSIDE DOWN and use the piece to press the plastic piece in very firmly. Reverse the top piece and finish the assembly.
Second, if the expander plug is loose or just not up to the job, it may be a factor. I know-in theory- that it is only there for adjusting preload, but in practice a loosening headset is very often caused by a wimpy expander plug. A robust plug firmly installed or even a wimpy one epoxied in will almost always solve that problem. BTW, Deda and ITM both make great expander plugs.

[seandonovan]

Don't forget the carbon paste! I'd be shocked if Park didn't mention it, but just in case...

[5 8 5]

Agree with seandonovan. Try using carbon paste on the steerer. The top cap assembly is only to preload the headset before clamping the stem.

[hillrider]

Has anyone removed the bung and top cap on a carbon steerer after tightening of the stem and found the headset stays nice and tight,plus saving grammes in weight??I know it should in theory,but like most,I find my headset coming loose about once every 3 weeks despite torqueing everything correctly.

[bontie]

New bung seems to have sorted the issue. Thanks everyone.