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Star nuts, expanders and a carbon steerer

GiraffotoGiraffoto Posts: 2,078
edited May 2013 in MTB workshop & tech
For my forthcoming new build I have a rigid carbon fork with a carbon steerer. Now, the first thing everyone says is, don’t fit a star nut in a carbon steerer, or the world will end (I’m paraphrasing). In any case, the steerer is made of a lot of carbon, so the spare star nut that I have won’t fit down there anyway. My next guess was a Hope Head Doctor, which is also too big to fit and so will be going onto my son’s bike when it’s built up. I have no evidence that any other expander will be any better fit, so I’m left with two options:

(1) Try my luck with an expander bolt that’s sized for a 1” steerer, and wrap a bit of inner tube around it to make it fit.

(2) Forget star nuts, expander bolts and the like, and set the headset preload with a length of threaded rod passed through the steerer and a big washer on each end. Then when the stem is nice and tight, just stick something like a bar end plug in the top of the steerer to finish it off

Which of these options seems the best? The second one is a dead cert for getting the headset properly adjusted, but I do just wonder if the first one is worth a go.

EDIT:
Well, to save you reading the rest of this thread, it turns out that a top cap sized for carbon steerers (no more than 22mm) is where it's at
Specialized Roubaix Elite 2015
XM-057 rigid 29er
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Posts

  • mattvmattv Posts: 992
    Or you could go to a decent local bike shop and get the correct expander.... Hammering a star nut into carbon fibre is not a good plan. Although the first generation of a budget well known bike brand had them fitted this way. You are not the only person to have found the hed doctor doesnt fit, its designed for aluminium steerers not carbon (which are thicker walled). Get a specific road bike one.
  • estampidaestampida Posts: 1,008
    and for No 2

    I used to use 1 of these and USE make something similar, the azonic 1 even seals the end of the steerer, its not that light though......

    http://www.jensonusa.com/!lM40I!u1Bm-Jr ... ad-Lock-II
  • benpinnickbenpinnick Posts: 4,148
    FSA, BBB, Deda - loads of people make the right thing, like a hope hed doctor but longer and thinner. Should be around £8. Job done.
    A Flock of Birds
    + some other bikes.
  • njee20njee20 Posts: 9,613
    Number 2 is unlikely to work as the chances are the steerer is closed at the bottom?

    Just get the right expander.
  • rrsodlrrsodl Posts: 486
    Definitely not a star nut.

    I use a bung on mine, came with the forks but you can buy one.

    CRC sells the longest bung I've seen around at 90mm - not sure if it offers any extra security though.

    The bung that came with my forks is close to 50mm.

    You need to tight it to about 8NM
  • OuijaOuija Posts: 1,386
    Option 3) Do neither and fit an external expander......

    $T2eC16dHJHgE9n0yHDnpBRVFD-m!zw~~60_35.JPG
  • cooldadcooldad Posts: 32,599
    And a spacer will help how????????
    I don't do smileys.

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  • GiraffotoGiraffoto Posts: 2,078
    Thanks for the replies/advice. It's good to see that I wasn't misinformed about star nuts and carbon steerers and they really are to be avoided! The consensus appears to be for a better expanding plug than the Head Doctor, can anyone recommend a particularly thin one?

    As an aside, although I like the concept of the adjustable space under the stem . . . I'd always be worried it was about to shorten itself, and can't see how you'd apply precise torque to it. Novel idea though.
    Specialized Roubaix Elite 2015
    XM-057 rigid 29er
  • njee20njee20 Posts: 9,613
    The consensus appears to be for a better expanding plug than the Head Doctor, can anyone recommend a particularly thin one?

    You don't need a particularly thin one, just one designed for a carbon steerer, loads out there.
    As an aside, although I like the concept of the adjustable space under the stem . . . I'd always be worried it was about to shorten itself, and can't see how you'd apply precise torque to it. Novel idea though.

    You could get a c-spanner on that, quite a neat idea, but doesn't achieve anything - you could use it to preload the headset if you had a top cap to bear against, but that requires something in the steerer to bolt on to!
  • benpinnickbenpinnick Posts: 4,148
    Njee - I think the idea is that you use it to take up slack once the stem is on and bolted up. Can see it staying tight though.
    A Flock of Birds
    + some other bikes.
  • OuijaOuija Posts: 1,386
    Giraffoto wrote:

    As an aside, although I like the concept of the adjustable space under the stem . . . I'd always be worried it was about to shorten itself, and can't see how you'd apply precise torque to it. Novel idea though.

    Got five of them of different sizes on five different bikes. Been using them for the last two or three years and never had a problem with them. Takes seconds to adjust, without the use of tools (just reach down and twist the top and bottom halves in different directions). And of course, there's no need to loosen or adjust the stem, unlike internal nuts and expanders, so none of the hassle of having to line your stem back up with your front tyre afterwards etc (once the stems on and tightened up, you never have to touch it again). They actually have two rubber o rings on the inside that clamp onto the steerer tube so that they don't want to turn independently of the steerer (also prevents water ingress on the steerer, which is why i use them with aluminium and steel steerers).
  • clamps81clamps81 Posts: 315
    Got a superstar expander and it's done the job for me.

    http://superstar.tibolts.co.uk/product_ ... cts_id=117
    Nukeproof Mega AM


    Tomac Snyper - Now sadly in pieces
  • njee20njee20 Posts: 9,613
    Got five of them of different sizes on five different bikes. Been using them for the last two or three years and never had a problem with them. Takes seconds to adjust, without the use of tools (just reach down and twist the top and bottom halves in different directions). And of course, there's no need to loosen or adjust the stem, unlike internal nuts and expanders, so none of the hassle of having to line your stem back up with your front tyre afterwards etc

    How does that work then? If your stem is tight then surely you can't adjust the height?
  • cooldadcooldad Posts: 32,599
    But you could preload the bearings. Still looks like an answer to a question never asked though.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • OuijaOuija Posts: 1,386
    njee20 wrote:
    Got five of them of different sizes on five different bikes. Been using them for the last two or three years and never had a problem with them. Takes seconds to adjust, without the use of tools (just reach down and twist the top and bottom halves in different directions). And of course, there's no need to loosen or adjust the stem, unlike internal nuts and expanders, so none of the hassle of having to line your stem back up with your front tyre afterwards etc

    How does that work then? If your stem is tight then surely you can't adjust the height?

    The height of the stem? Why would you want to adjust the height of the stem once you've got it at the height you like?

    A top cap (with star nut or internal expander) lowers the stem (or pulls up the steerer if you prefer to think of it that way) to increase pressure on the headset. The external expander......mmmmm, expands, increasing the distance from top of the headset to the bottom of the stem, which again, increases pressure on the headset. We're only talking a millimeter or two to go from a completely slack fork to a tight one. Less than a quarter turn of the external expander.
  • njee20njee20 Posts: 9,613
    I misunderstood your post - thought you were saying the expanding spacer was good because you could adjust your stem height without having to adjust the stem.

    As a way of adjusting the headset that strikes me as a non issue, I can't remember the last time I adjusted one without wanting to remove the stem. Fit headset, adjust. Done.
  • OuijaOuija Posts: 1,386
    cooldad wrote:
    But you could preload the bearings.

    No. It post-loads the bearings. Internals (star nut or bung) pre-load the bearings and then pass control over to the stem after you've tightened it up (at which point the star nut/bung becomes redundant). I think people aren't quite grasping how it works.

    1) Set to it's smallest height and slide on steerer.

    2) Put stem on, line up with front wheel and tighten up.

    3) Grab hold of the two knurled sections on the top and bottom of device and twist in opposite directions to expand (pushing the stem and clamped steerer upwards, so the bottom of the device is pressing on the headset bearings with more force).

    Simple.

    There's no particular advantage to using it over internal pre-loaders, such as the star nut/bung, other than it requires no tools to adjust in the future. Whereas with the star nut/bung, if you feel your headsets getting a bit loose, you have to reach for some allen keys and mess about unclamping the stem, re-tightening the top cap, aligning the stem with the wheels again and then re-tightening the stem bolts, which can take a few minutes. With the external device, it's simply a case of reaching down and giving it a quick twist (only takes 3 seconds... i've done it while standing at traffic lights).

    Hell, i've even got them on two bikes with star nuts in, just to save me hassle when i'm out and about.
  • njee20njee20 Posts: 9,613
    Fair enough, like I say, I just adjust my headsets properly first time, so there's no need to adjust at some traffic lights ;-)
  • The RookieThe Rookie Posts: 27,804
    Ouija wrote:
    cooldad wrote:
    But you could preload the bearings.

    No. It post-loads the bearings.
    Rubbish, suggest you find out what pre-load means.....
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • cooldadcooldad Posts: 32,599
    One problem with that thing - nothing to hold the topcap on.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

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  • Chunkers1980Chunkers1980 Posts: 8,035
    You could fit a sfn to do that...... Wait a minute...
  • OuijaOuija Posts: 1,386
    Ouija wrote:
    cooldad wrote:
    But you could preload the bearings.

    No. It post-loads the bearings.
    Rubbish, suggest you find out what pre-load means.....

    Lol. Ok, Einstein.. enlighten us?
  • cooldadcooldad Posts: 32,599
    See two posts above. Whatever term you use its still a redundant idea. But preload just means load before you use them. Post would mean after. Unless you mean get RM to do it.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • The RookieThe Rookie Posts: 27,804
    Ouija wrote:
    Ouija wrote:
    cooldad wrote:
    But you could preload the bearings.

    No. It post-loads the bearings.
    Rubbish, suggest you find out what pre-load means.....

    Lol. Ok, Einstein.. enlighten us?
    Preload is the load applied to something during the 'build', in this case the headset bearings, prior to the design load being added, in the case of a headset you add preload and then when you get on the bike that adds the load - from wheel via axle up through the forks - plus to the lower bearing and minus to the upper (due to slight deformations) which is why you need preload to stop the load on the upper bearing going negative which would mean loose.

    Why make a comment about something when you didn't really understand it, especially when it's not hard to find out what it is. http://www.nmbtc.com/bearings/engineering/preload.html
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • njee20njee20 Posts: 9,613
    One problem with that thing - nothing to hold the topcap on.

    You don't actually need a top cap though, although I found my headset came loose more when I didn't use one - hence the need to tighten ones headset with this thing at some traffic lights I guess. I guess even though its not tight the top cap stops the very small movement of the stem up the steerer.
  • cooldadcooldad Posts: 32,599
    You don't need one, but it does leave an ugly looking hole without. I'm not a tart but....
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • OuijaOuija Posts: 1,386
    cooldad wrote:
    You don't need one, but it does leave an ugly looking hole without. I'm not a tart but....

    Top cap rubber bung.....

    31kX13Vu0cL.jpg
  • cooldadcooldad Posts: 32,599
    No thanks.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Chunkers1980Chunkers1980 Posts: 8,035
    Yeah reminds me of shitty quill stems
  • cooldadcooldad Posts: 32,599
    I wonder if posted in Cruddie how many uses we could think of.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
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