headset spacers moving

shiznit76

Hi,
The spacers on my carbon steerer tube can be turned even when have top cap on tight. I know I need tighten this up before tightening the stem so that isn't the issue. I have also tried a smaller and larger spacer above the stem but again no difference. There doesn't seem to be play in the headset and fork turns smoothly, but concerned that I can move the spaces, I thought they should be compressed too, am I correct in this?

N0bodyOfTheGoat

From my own experience of this, check the steerer bung is fully inserted into the steerer and correctly tightened using allen key or torque wrench.

shiznit76

Is that the compression sleeve inside the tube do you mean?

N0bodyOfTheGoat

Yep, mine was a tiny bit loose and was very slowly being pulled out of the steerer, slackening the spacer gap.

shiznit76

ah, think that is the problem as it was quite loose and coming up as tightened, will look at it when get home,
Cheers dude

bondurant

So just to be clear, the top cap being tight does not in itself mean the spacers will be compressed. If you take off the top cap you will see the steerer bung underneath. This has to be tightened such that it expands to press against the inside of the steerer tube. So when the top cap is replaced and tightened, it pulls upwards on the bung, which is where the compression comes from. More to get this down for anyone who has the same problem as I think you get this now Shiznit.

shiznit76

Cheers, the compression bung needs to be tightened, it came out with ease when I was trying to set it up (bike had been in at shop to get steerer tube cut, they must not have tightened the bung up properly!!). I have seen a video on youtube with exact same bung and they guy tightens it tight inside the tube using a 6mm allen key, so will look at this when I get home

i.bhamra

It needs to be tightened enough so that it doesn't move when the top cap is tightened just enough to remove play in the headset. Over-tightening the bung can cause a bulge in the steerer that makes it difficult to get the stem on/off or worse damages the steerer tube terminally. Over-tightening the top cap makes steering stiff and puts excessive loads on the headset bearings leading to premature failure (as well as pulling the bung up).

shiznit76

Video on youtube says tighten to appout 8nm

It is moving about when I try and tighten it and also coming out of steerer tube so presume that problem is it hasn't been tightened enough in the steerer

i.bhamra

Really depends on the exact bung and fork, if they are the same then fair enough (if you trust your torque measurement!). Personally I'd just go with a bit of trial and error and gradually tighten if necessary, easy to stick a couple of allen keys in your pocket on a test ride and adjust as necessary.

shiznit76

does the bung inside not need be snug to allow the top cap compress the headset when it is tightened down in to it?

i.bhamra

Snug yes, but not necessarily 8nM. The primary function of the bung as you correctly state is to allow the top cap to compress the headset enough to remove play- this doesn't need much effort at all as you will see that as soon as put any significant torque on the top cap bolt the steering will become stiff. Once the play is removed it's the clamping force of the stem bolts that holds everything in place and prevents play from developing. It follows that the bung doesn't need to be very tight.

The key when tightening down the top cap is that once you remove play you should be able to lift the front end of the bike up and lean it to the side and the bars should move freely on their own with no resistance. (You should also notice that the spacers at this point should not be easy to turn, as there is no play in the headset).

I'm probably sounding OTT here but have witnessed carbon steerer tube failure when a rider was braking heavily off a decent at speed. It wasn't pretty....

shiznit76

chees, thanks for advice, will go with your side of the bung being tight, but not overly so

shiznit76

Jobs a good one, it was the bing in steerer tube that needed tightened. Done it up and now every th ibg snug! This site is a gidsend! And won't be using that shop again in a hurry!
Cheers for help folks