Carbon Steerer - Star Nut?

wilkij1975
wilkij1975 Posts: 532
edited February 2016 in Workshop
Hi All

Just a quick one. Can you use a star nut in a carbon steerer tube? I have an ITM 50mm bung in it at the moment but it has come loose a few times.

Cheers
Carbon 456

Comments

  • Cleat Eastwood
    Cleat Eastwood Posts: 7,508
    i just got a new headset - and new carbon forks and the headset came with a star nut - the warning was emphatic - do not use on carbon steerers. It can shatter the carbon by all accounts. bungs are cheap

    http://www.planet-x-bikes.co.uk/i/q/FSP ... _2___11_18
    The dissenter is every human being at those moments of his life when he resigns
    momentarily from the herd and thinks for himself.
  • Monty Dog
    Monty Dog Posts: 20,614
    At the risk of damaging/cracking your steerer, then by all means - whilst Cannondale say starnuts are OK for their carbon steerer forks, almost everyone else doesn't, so the questions is, is this a risk you want to take?
    Make mine an Italian, with Campagnolo on the side..
  • fludey
    fludey Posts: 384
    As above don't use star nut on carbon steerer get a new bung type, seen plenty of pics on here of peeps that have tried then questioned where the cracks have come from.
    Felt AR4
    Planet X Pro Carbon 105
    MTB Kona Kikapu Deluxe with a few upgrades!!
  • wilkij1975
    wilkij1975 Posts: 532
    Cheers all.

    I knew it wouldn't be a good thing but wasn't really sure why. I'll stick with the bung and if I have to tighten it every so often then so be it.
    Carbon 456
  • sungod
    sungod Posts: 17,340
    usually the bung is only tightened to preload the headset, once the stem is tight, the bung doesn't do anything except maybe provide internal support to the steerer where it's clamped, so being loose doesn't matter that much

    but if the bung is slipping, try removing it and making sure there's no grease on the surface/inside the steerer, then re-install it and do up the expander to the manufacturer's recommended* torque (you could also put some assembly paste on the bung surface to increase grip), then refit stem, adjust preload, tighten stem

    * for install instructions, you can contact itm

    http://www.itm.it/itm_tech/en/contacts/
    my bike - faster than god's and twice as shiny
  • g00se
    g00se Posts: 2,221
    Or get a different bung. I found the Deda ones cheap and good.
  • bedroomtraxx
    bedroomtraxx Posts: 2
    I recently built my own bike with carbon frame and forks. My headset came with a star nut and as i was unaware of bungs i fitted it.
    I have not ridden the bike yet as its a summer bike.
    Can i remove the star nut without damaging anything and fir a bung and sleep easy that it'll be ok? This thread has me super worried!
  • sungod
    sungod Posts: 17,340
    is the steerer cf or alloy? there are plenty of carbon forks with an alloy steerer

    once a star nut is in, you can drill out the centre with the largest bit you can use without risk to the steerer, be gentle so that you don't simply push the nut further in

    once you've done this, put a hooked *stiff* wire through the hole and position the hook to support one edge, press the opposite edge down to rotate the remains in the tube, you can then use the hooked wire to pull it out
    my bike - faster than god's and twice as shiny
  • andy_wrx
    andy_wrx Posts: 3,396
    The star nut works by having sharp points on it like barbs which dig into the inside of the steerer tube and thus resist it being pulled-out as you tighten the bolt, no ?
    - doesn't sound what I'd like to be doing to a carbon tube...

    And a bung is often an inch-and-a-half long, so it can act as a stiffener inside the tube to protect against you overtightening the stem and crushing it
  • captain_tiara
    captain_tiara Posts: 106
    +1 for Deda bungs

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