Bicycle Mechanics - problems with chorus threadless headset

Some dozen years ago, I had a high end Bianchi with a threadless carbon steerer and a chorus group. I was going crazy because the headset would loosen with every ride. I torqued the clamp bolts to spec, and then tighter. Seems I was even messing with the bolt that went through the cap.

I finally figure out that it was because the nylon conical centering washer was not rigid enough to keep the steerer tube centered. The movement was forcing the stem up. I put in a Cane Creek headset with a metal centering washer and all was right with my world.

I would hope that Campy would have fixed the problem soon than later. I mentioned the problem to a shop mechanic once and just got a blank look. Have others had experience with this problem. It's a moot point for me at this point, but I am curious.

Huh? I'm not clear what you just wrote. Are you saying the plastic piece has a rigidity problem but yet can push up a firmly attached stem? It is all the more puzzling because my Campagnolo threadless headsets do not loosen and neither have I heard of other Campagnolo threadless headsets loosening (they're all the same design).

My guess is your headset was not installed properly. Unlike the Cane Creek/ Aheadset threadless headsets, the Campy does not use a split ring (there is little doubt the split ring is the better design). The Campy Threadless design uses a compression ring that is pressed inside the upper cone race. When this is installed it needs to be firmly pressed against the bearings; Campy says to turn the top bearing cover upside down and use it to press down the upper cone race. http://www.campagnolo.com/repository/documenti/en/7225190-Hiddenset_headset-10-06.pdf. After that you install the top cap and and set the pre-load with the top bolt as usual. When you install an Aheadset you do not have to press in the split ring in this manner as the pre-load also seats the split ring; with the Campy threadless headset it does not.

The top cap that comes with campy hiddenset threadless headsets has a thick round plastic ring fitted to their underside. this ring can interfere with proper headset adjustment if it touches the top of the steerer tube and can cause problems like what you describe. There are two primary options to deal with this:
1. Cut the steerer tube a little short than one would normally to prevent contact (not ideal)
2. Remove the ring by easily popping it off. This ring is fairly superfluous and its removal has no negative impact on performance of the part.

-j

I have a de rosa with an integrated headset that has a plastic cone thing maybe similar to the one are you talking about and I never had a problem with that ever. The plastic piece you are talking about centers the bearings and is compressed from the top with the spacers, stem and with the top cap.

If the top cap is not tight enough the stem will get lose and then you have the problem with lose headsets, just tight the top cap, check there is not play, in some cases you have to over tight tiny bit. Then tight the stem, done.

Many people complain about campagnolo, never had a problem with campagnolo neither 30 years ago, neither today. You arent the 1st one to rant about campagnolo and sure you wont be the last one. Clearly user problem.

Thanks all. MrFly: I am not saying that the plastic is forcing things up per se, rather that it allows a rocking motion that allows the fork to force things up.

Campy has always been gruppo of choice except when Dura-Ace DT indexed shifting first came out. Tok campy several years to get to the point that I was comfortable with their ergo lever system. Will know to look further the next time. Thanks for the link. I'm not using a hiddenset and couldn't find a manual for a standard headset on the campy site, but it is a moot problem. I certainly didn't know to use the top cap to push the retainer down. Will accept my ignorance and know to look further the next time if there is a next time.