I’ve got an old Pinarello FP2 (2010 I think) which I’ve just replaced the top bearings on, and I’m now struggling to get rid of some play. The bike uses an unusual system where the bearings press into the frame, and the lower bearing presses onto the fork. At the top, the bottom spacer is like this:

and the metal bit at the bottom pushes into the gap between the bearing and the steerer.

The problem is that the i/d of that metal ring is slightly larger than the o/d of the steerer, and so you get a little bit of play.

I’m used to ones that have a split ring like this:

which compresses down to a tight fit.

I don’t really understand how this Pinarello one is supposed to work, as without a split to allow it to compress, it’s always going to be a loose fit on the steerer.

Can anyone shed any light on this?

You’d think there would be a split / compression ring. You definitely sure there were no other parts to the headset when you removed? Always worth triple checking the floor in case a compression ring got stuck with grease to the bottom of the top cap and fell off somewhere before you put it down.

Well, I’ve been thinking the same thing, but I can’t find anything, and I can’t imagine how it would fit, as that metal ring does slot very tightly into the bearing.

I have a feeling that that top cap is now sitting fractionally higher than it was before, but I can’t be certain, and it really doesn’t want to go on any further.

If you can bare to take it apart again, it might be worth posting up a picture of all the component parts you have. Might be able to figure out what’s going on.

Go simple- fork bung not gripping?

Go simple- fork bung not gripping?

Sadly not that simple. Was just getting the carbon paste out when I realised the problem was something else.

Here are some photos. Assembled:

With the conical spacer pulled up a bit:

The spacer has a couple of rubber seals in it which is how it defies gravity in the photo, but I struggle to believe that that’s all that supposed to hold the steerer in place. The metal ring on the bottom of that spacer is a tight fit into the bearing, but there’s play between the steerer and the spacer.

The full list of components are (in order) fork, lower bearing, frame, upper bearing, conical spacer, normal spacer, stem, spacer, bung, top cap.

I’m not sure what’s going on in this video, but there’s some magic at the bottom end of the headset (notice how he just pulls out the compression ring at the end).

[video]https://www.youtube.com/watch?v=l448CuZLv14[/video]

I’d be tempted to have another go at levelling the top of the steerer tube, its unlikely to be that, but you never know.

I think both bearings need to have an interference fit on the steerer, are the replacement bearings the same ID as the original ones?

I’m not sure what’s going on in this video, but there’s some magic at the bottom end of the headset (notice how he just pulls out the compression ring at the end).

Yeah – that’s a slightly different system, as it’s got a separate compression ring, rather than a conical spacer with a metal ring on the bottom.

I think both bearings need to have an interference fit on the steerer, are the replacement bearings the same ID as the original ones?

Yes, although the top bearing doesn’t have an interference fit on the steerer. It has a press fit onto the ring at the bottom of the conical spacer, but the spacer is not tight on the steerer, other than by the rubber seals inside it.

The spacer has a couple of rubber seals in it which is how it defies gravity in the photo, but I struggle to believe that that’s all that supposed to hold the steerer in place. The metal ring on the bottom of that spacer is a tight fit into the bearing, but there’s play between the steerer and the spacer.

That’s exactly how Chris King headsets work (or used to). Its a bit crap but you might be able to reduce the play by replacing the O-rings in the headset cap.

Thanks – that’s useful to know, and the more I think about it, the more I think that this must be how it works. The fact that there’s two separate O-rings in that top cap suggest that they’re not just there for sealing.

I might try seeing if it can be converted to use a split compression ring, as in the video.