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Carbon steerer - headset issues

reformedfattyreformedfatty Posts: 543
edited April 2017 in MTB workshop & tech
First time fitting forks with a carbon steerer bung and I can't seem to get the headset tensioned. Photos on the link below.

It feels like the steerer bung is expanding the steerer tube enough that the pressure pulling everything together isn't enough and it's effectively just tensioning the stem against the 'bulge' in the steerer tube, if you see what I mean...

I've not used an expander plug on a carbon steerer before and wasn't really expecting the steerer to apparently change size, but say if I install the expander plug and then try and put the stem on, it won't go on until I release it's tension. Is this normal??

https://drive.google.com/open?id=0B6fT6 ... DctZDhKRjQ

Posts

  • As ever after a sleep things are a little bit clearer

    I'd bought a new crown race for this fork - I want to compare it to another one and decide which to keep, so wanted to easily swap. My memory recalled the headset as being a nukeproof warhead one, so I bought that crown race. Thinking about it, it's not a nukeproof one at all - that was another one of my bikes. They are quite different and would probably explain my problems.

    I can't find my receipts for this one and am struggling to recognise the logo.. looking at the last picture does anyone have any ideas?
  • daniel_bdaniel_b Posts: 8,777
    Hmmm, not 100% sure what is going on here, so what I will do is offer up personal experience of my build with a full carbon steerer.

    On mine there was a 8mm (?) bolt inside which adjusted the tension it had within the steerer - I tightened it to what I thought was enough, but on tightening the top cap, it was pulling the bung up the headtube. After some googling, I found a video from Scott that recommended 8nm tension for the bung - this was a lot, but once applied it has stayed in place, and the problem has not re-occurred.

    I'm not saying 8nm is definitely what is required for yours, but perhaps it needs a bit more tightening?

    I hope that helps, but apologies if I have missed something obvious!
    Felt F70 05 (Turbo)
    Marin Palisades Trail 91 and 06
    Scott CR1 SL 12
    Cannondale Synapse Adventure 15 & 16 Di2
    Scott Foil 18
  • Daniel B wrote:
    Hmmm, not 100% sure what is going on here, so what I will do is offer up personal experience of my build with a full carbon steerer.

    On mine there was a 8mm (?) bolt inside which adjusted the tension it had within the steerer - I tightened it to what I thought was enough, but on tightening the top cap, it was pulling the bung up the headtube. After some googling, I found a video from Scott that recommended 8nm tension for the bung - this was a lot, but once applied it has stayed in place, and the problem has not re-occurred.

    I'm not saying 8nm is definitely what is required for yours, but perhaps it needs a bit more tightening?

    I hope that helps, but apologies if I have missed something obvious!

    Think it's my crown race in the end as mentioned above - I used a mini torque wrench to do the bung up to 8nm, and at that point with the top cap / bars done up the bung was 100% secure
  • To finish this one out.. sorted out the front end with changing to the correct crown race.

    Now on to the battle of sorting out the myriad adjustments of the rev dual airs..
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