Headset play/loosening. Niner fork. What am I missing?

I have recently fitted a Niner fork to my Scandal. An LBS fitted a new hope headset and the crown race. When I ride the bike play is developing in the headset. Releasing the stem bolts, tensioning the top cap and re-tightening the stem bolts eliminates the play but it soon returns.

This is my first experience with a carbon steerer. Is there something obvious that I’m missing? Should I be using some carbon paste?

Thanks for your help.

Chris

Three headset things to check – are the cups fully inserted in the frame or are they moving into place as you ride? Was lots go grease used in assembly and now being moved aside as you ride? Is the expander in your steerer tube loosening and migrating up the steerer tube? Or….is it something else rather than the headset,, like a 2 piece disc rotor developing play or just being loose? Loose calliper?

Me too!
Carbon on-one fatty fork on my voodoo Wazoo.
These expanding preload things don’t seem to work too well.

Thanks MrTricky.

I’m pretty sure it is the headset. You can feel the play. I will work through the list of three things and check each in turn.

Chris

The expander is the most likely cause. Check the design of it and the fitting instructions. On many you have to insert the expander, tighten it up and then fit the headset cap etc. Some folk seem to forget that middle section.

Hi Scotroutes

That makes sense. The expander came with the fork and has a tapered design which pulls into itself when tightened.

Once tensioned and the stem bolts tightened the fork sits well in the headset with no play. At this point is the expander not redundant?

Cheers

Chris

It should be, yes. But in reality it’s not. I’d put £10 on it being improper fitting of the expander, and as Scotroutes says you’ve not tightened it once fitted.

It theory, it should be. The stem bolts should be tight enough to stop any play developing in the headset. However, that’s obviously not happening here. It might be more re-assuring to have the stem in place when doing this (assuming the stem and bung are around the same point on the steerer).

Applying some Carbon Assembly Paste to the inside of the stem might provide more friction. Otherwise, I’d suggest the bolts just aren’t tight enough. I’m assuming you’ve set them to the correct torque value? If so, and they are still allowing the stem to slip up the steerer tube in use then what I would do with my bike is increase the torque slightly. If the expander/bung is inside the part of the steerer that the stem is gripping then the chances of causing any damage are much reduced.

+1 on suspect it’s the expander. Riding puts way more load through than you can get with those expander plugs so I suspect it doesnt quite have the preload it should. I use a bit of carbon paste on the plug to help stop it sliding.

I’m embarrassed to say I completely balls’ed up the carbon expander thing on my carbon fork steerer. I’m still trying to move on but it’ll be a while before I’m allowed to live it down.
Who would have known that you have to screw in the smaller allen bolt inside the bigger allen bolt so that it ‘expands’ and grips the inside of the steerer before you tighten the bigger outer alien bolt which compresses the bearings?
Tricky, devious buggers – those carbon steerer expander bolts……..

The expander only preloads the bearings. The steerer keeps everything tight.

Once the stem is fitted, and all is tight, you can remove the expander for all the good it does.

The stem is moving on the steerer. Buy a torque wrench and some carbon paste.

I’m also having frustrations with this. Set up preload , tigten stem bolts, comes loose!

So I’ve had a branded new heads set, checked expander several times, carbon paste, changed stem and it still comes loose.

Anything else?

Have you done this?

Who would have known that you have to screw in the smaller allen bolt inside the bigger allen bolt so that it ‘expands’ and grips the inside of the steerer before you tighten the bigger outer alien bolt which compresses the bearings?

Take the centre bolt and top cap out, you should see a larger hex key fitting. This expands the fitting inside the steerer, you then preload as normal.

I had no idea about this on my carbon fork having never had carbon forks before.

What probably happening is the expander wedge is moving up out of the steerer in use, as it’s not right enough.

It’s worth tightening the expander up (as above) with the stem fitted (but not done up) as I have seen one where the steerer tune bowed out so much when the expander was tightened you couldn’t fit the stem.

The wedge moving would be a symptom not the cause. If it’s moving, it’s because it’s being dragged by the stem moving on the steerer.

+1 wot jam bo said.

Sorry I’m a little confused. I thought you tightened the bigger bolt first so the wedge doesn’t move, then the top cap bolt, then the stem bolts. That’s certainly what the ENVE instructions say.

Are you saying the expander is not low enough in the steerer?

Thanks.

I’m with jambo too.

The stem pinch bolts should be holding it tight. The preload should be just to set the tension.

Just like hollowtech 2 bb/ crank arm. The little black screw thing doesn’t hold the crank on, the pinch bolts do that!

Yes that’s right. You tighten the big bolt to hold the expander in place first. I usually put carbon assembly paste on the surfaces that contact the steerer or the wedges tend to lift themselves out of the steerer when you tighten the top cap.

I had a similar problem with an aluminium steerer a while back and after eventually changing the stem (cnc’d lump now instead of the cheap on-one forged piece)it’s been behaving.

It was a thomson stem, and now I’ve changed to an el-cheapo cube stem no real difference. Other than you can get a bit more torque on the bolts as the thomson bolts can round off easily.

Problem with the expander plugs is not them slipping in use but slipping when initially tightening and bottoming out on the top cap without you realising. The headset will seem tight enough as it has pre-loaded it a bit but it will not be enough.

Be VERY careful with them, especially on carbon steerers, and use carbon paste.

I always tighten them with the stem bolts just nipped up enough to make moving the stem by hand difficult as it resists the expansion. Another option is use a long bolt all the way through and then refit the expander and top cap after but that wont work on carbon crowns as they have no holes in the bottom.

So you’re saying tighten the stem bolts a bit – then set the preload – then tighten the stem bolts properly?

I would sat I’m pretty much doing what this guy is doing apart from the 5mm spacer under the cap before the stem. Which could cause issues I guess.

I think I’ve solved mine. Top cap is too close to the expander. Needs the spacer… The shape of top cap is slightly pyramid like underneath which means it’s compressing against the expander as per Andy’s description.

I’m hopeful after six months of faffing.

Thanks to all in this thread for ideas.

The expander can be moved further down the steerer in this case – assuming the top cap is bottoming on the expander and not on the steerer itself, in which case the spacer would be the correct fix.