Viewing 9 posts - 1 through 9 (of 9 total)
  • Ti steerer star nut. Is that a thing?
  • IvanMTB
    Free Member

    Hi,

    Finally managed to put suspension forks into my Ti hardtail.
    So pulled out original rigid forks and found picture like that.

    Star nut a bit mangled on 2 leafs and pulled out of the steerer quite a bit.

    And it left me thinking…

    Star nut was fitted with proper tool, steerer was dry and clean inside, no greasing, I do not think I over tightened it as headset was spinning freely.
    So what caused it?
    Crap installation? Matter of steel/Ti interface? Or me just being tad too enthusiastic whilst riding rigid bike?
    Truth to be told I had few instances of slightly rattly headset that is tightened back, that now in the hindsight looks like star nut was just migrating up.

    So… Is there anything like special star nut for Ti steerers, something like one for carbon steerers?

    … or I just need to accept the fact that suspension forks is for rough riding, rigid forks for someone with more finesse than a brick, or more sedate rides 😀

    Cheers!
    I.

    scaredypants
    Full Member

    Ti’s quite hard, isn’t it ? Maybe the nut just wasn’t getting any purchase.

    (once stem is bolted on, the nut and the cap are totally redundant)

    scotroutes
    Full Member

    Once the stem is tightened, the star nut serves no purpose (in theory at least). If the headset is coming loose then it looks like your stem bolts haven’t been tight enough.

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    ta11pau1
    Full Member

    It’s not doing its job if it’s moving upwards inside the steerer though, you can’t tighten the headset if the bolt keeps moving up.

    Get a hope head doctor, should sort it.

    IvanMTB
    Free Member

    Might be… I’m a bit paranoid about over-tightening of steam bolts as had it once in a very, very bad way, that cost me a lot of nerves and a bit of money as well.

    Cheers!
    I.

    seventy
    Full Member

    If the forks are ti with a ti steerer then it may just be that the forks have a bigger ID than a steel fork and the nut isn’t quite the right size. Some star nuts are bigger than others. I’ve always used CK star nuts with lightweight steerers (thin wall) as their OD is slightly larger than most others.

    argee
    Full Member

    Titanium isn’t that hard, i’d say it’s just gone in uneven, maybe a bit of overtightening, as we all do it, all that’s needed is to take up the slack, but we all do that extra turn!

    Remove, put new one in, test, it’s so easy to put the star nut in just a little off.

    mutepoint
    Free Member

    My Planet X Dirty Harry and Niner forks with FSA headset used to suffer coming loose and needed preloading a couple of times.

    I put it down to ROUGH RIDING like DMX.

    PhilO
    Free Member

    As others have said, the star nut shouldn’t ever come under high loads, as the stem should lock the axial preload in place. But under heavy braking the radial loads on the head bearings will be a lot higher than the static load, and depending on the contact angle of the bearing that can result in high axial loads as the balls ride ‘up’ the radius of the raceway (imagine the bottom of the raceway as a gently sloping ramp up which the ball will run). If the stem isn’t clamped well enough to resist those axial loads it will move (a microscopic amount) up the steerer, increasing the load on the star nut and moving it an equivalent microscopic amount. Repeat several thousand times over a few rides and the headset is loose, so you readjust it, and the whole cycle starts all over again.

    Short of changing the stem to one that clamps more securely, a head-doctor style plug would seem to be the solution. It won’t stop the movement, but will be effectively re-set in the steerer each time you adjust the headset, so you won’t get the long-term effect of the moving star nut.

Viewing 9 posts - 1 through 9 (of 9 total)

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