Loose headset on carbon frame
 

Hi folks, I'm having trouble with movement on the headset on my new carbon fibre frame (import from china) I've slacked off the bolts on the stem and tightened up the crown cap (plug as carbon steerer) but there's still movement when I rock it on the front brake. There is plenty of gap for the crown to pull up the fork (it doesn't bottom out on the top of the steerer tube)

There seems to be play in either the bearing in the cup (which is stuck in the frame) or the carbon steerer tube in the bearing (or maybe both)

Has anyone got any advice on how to solve this? I've heard of some people using epoxy resin glue to site the bearing more firmly in the cup for instance although I'm a bit reluctant to do this as I fear it'll never come out again.

Am I just missing something here?

Costello tapered headset if it helps (bottom bearing seems sound enough too)

Any help greatly appreciated! I just want to get on it and get riding but this needs correcting first! The rest of the build went swimmingly!

Cheers Ben :(

Do you have enough spacers under/over the stem? Once everything is together, there should be a 2-3mm gap between the top of the fork and the top of the spacer/stem. Also, are you sure all the parts of the headset are in there correctly? After the bearing, there should be a wedge-profile round thing which centers the fork.

Do you have the inverted split cone centering ring in place on the upper bearing and below the top bearing cover?

Hi thanks for your reply, yes got the spacers under and over the stem and there's at least a 5mm gap for the plug to pull in the fork tube up. The cone is in there too, it does seem a bit slack around the steerer tube though, although I suppose it's intended to then compress inwards around the tube when squeezed by the top nut.....l

The cone is supposed to be installed narrow end downward so it slips into the gap between the inner race of top bearing cartridge and the steerer tube and is forced downward and tighter by the top cover as the headset is adjusted. Do you have it in place that way?

Hi, yes that's exactly how it is....

If your bike has a carbon steerer, they usually use an expander plug (see link below). Sometimes this plug can come loose when you tighten on the top cap and pulls it up the steerer tube. Remove the stem, loosen the expander plug and make sure that is is seated level inside the steerer tube, then tighten this expander plug. Put back the stem and spacers making sure that fork steerer is lower by 2-3 mm from the stem. This gap is needed for the headset to be compressed. Thghten the top cap. Once this is snug, then tighten the stem bolts.


http://www.universalcycles.com/shopp...9&category=100

First of all, do you have an integrated headset (bearings drop into conical pockets in the frame) or a typical press-in headset. If press-in, are the cups secure in the frame, and the crown race secure on the fork? In integrated, do the bearings pocket cleanly and firmly?

If all looks before assembly, assemble it and press the split centering cone down by hand using one spacer. Does that bring the fork up tight? It may not be truly tight, that takes more than you can get by hand, but you should be able to see if the centering and tightening action is smooth. You can also try tightening the fork without the stem using a sleeve or a stack of spacers if you have enough. Not having the stem on might help you see what or where the problem is.

Lastly, make sure that neither the stem or lowest spacer is beaching on the top cup. On some headsets, the centering cone can pocket sub-flush and only a spacer narrow enough not to touch the cup is needed under the stem.

Thanks guys for your replies, it made me have a good long look at the set up yet again. You are both right in your advice, and it is an integrated headset. I think the plug had probably pulled up a bit and therefore beached on the top cap so it wasn't doing its job properly, however I also tried the whole set up using just a stack of spacers (had to steal a few from my sons mountain bike but that was quickly put back together with no hassle) guess what - it tightened up pretty well. So I took another look at the stem and this wasn't quite right. It's a Felt stem that has a kind of offset shim in it but it doesn't seem to sit down on the spacers evenly, that is to say it sits down more at the back than the front and therefore must apply uneven pressure to the bearing cone insert. Using just spacers showed that this is where the real problem lies. I think that a new stem should see the whole thing come good, though I can't really understand why I never experienced any problems like this on my Felt z90 (maybe I should've kept it - it got me from London to Paris, bless her little cotton socks!)

That bike can float or did they let you ride through the chunnel? :)

The shim is most likely to allow you to change the angle of stem in relation to the steerer.

http://2009.feltracing.com/09-catalo...able-stem.aspx

Luckily the ferry took care of that bit of the trip as I was a wee bit tired!

jsharr, that is indeed the beast in question, I think I might try rotation of the angled shim to what effect that has on proceedings and I'll post back with the results. I've ordered a new stem regardless to be honest as I just want it back on the road so I can use it. It is indeed a very strange fault indeed.......

will re-post with an update..... Cheers Ben

I'm missing Numbers..

Have Proper machinist's measuring tools? or can go where some are?

Headtube bore, may be for product A, headset type.
and you bought product B, for your headset.

.. If a picture is worth a 1000 words, a dimensioned blueprint is worth a 100 pictures.

Very cryptic.......eh? The headset came with the new frame as part of the deal if that's what you mean.....cheers BB

ps although that means nothing really ! They could have chucked anything in the box!

Apologies for not posting this update sooner, totally forgot and it might help someone else out there. I figured out this problem a while ago.

I was right that the stem needed to be changed as a vital piece of this was sold when I put the Felt on ebay so in effect this was incomplete. New stem bought which is spot on.

The crucial part of solving the problem was the actual expander plug itself. I was not aware that some expander plugs are actually meant to be installed in two parts. The bit that sits in steerer tube is meant to be separated completely from the top section. This plug is tightened up in the tube with its own bolt. Once this is secured you can then proceed to tighten everything up with the top part of the cap. Essentially the plug is in 2 parts but it looked as though it was all one!

Problem solved! :thumb:
http://bikeforums.net/attachment.php...hmentid=299754