Should I remove the starnut from my carbon steerer?

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TMI
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by TMI

I have a 2001 CAAD6 frame with TIME Slice carbon fork/steerer that came with a starnut installed. While working on the headset, I noticed that the starnut was slipping along one edge resulting in the nut sitting unevenly inside the steerer and the top cap bolt at an angle.

Should I remove the starnut altogether and replace with a compression plug like the KP017? Would it fit into this older fork?

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nickf
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by nickf

I had an old carbon fork with a junked up star nut before. I ended up just pushing the star nut lower into the steerer and used an expander plug. Worked like a charm. There was no way of pulling the old star nut out. Maybe someone will chime in with a way of getting one out without damaging the steerer.

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TMI
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by TMI

I have heard of others drilling out a starnut to remove it, and I have the tools to do it, but I wasn't sure if there would be any disadvantage to leaving it in and pushing it further down the steerer.

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Calnago
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by Calnago

No disadvantage to leaving it in. Pushing it further down and out of the way could be your best option as @nickf suggested. However, a starnut should never ever be used in a full carbon steertube to begin with. Are you sure there isn’t an alloy sleeve inside the carbon steertube. Alpha Q (acquired by True Temper) used to use this method, as did Cervelo. In those cases there is an alloy sleeve bonded to the inside of the steertube serving to both reinforce the steertube and also make the use of a starnut ok.
You could also drill it out if you desire as long as your careful not to touch the carbon steertube. And you won’t be scoring the inside wall of the steertube any further by pushing it down.
Either way would be ok, just be careful if you’re drilling it out.
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mattr
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by mattr

There was a cannondale CF fork that did specific a starnut, not sure if it is this one (probably not) but i've not seen one for ~10 years.

You can get the existing star nut out with a 7 or 8mm drill bit and a steady hand. You'll drill the core out and then the stars will collapse as there isn't enough material left to support them. You'll need a decent bit, some lubricant and a very steady hand (or a pillar drill)

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TMI
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by TMI

Here are pics of the fork and the removed starnut. A hole saw worked well on this starnut. I expected it would be larger. Waiting on a compression plug in the mail.

Image

Image

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Calnago
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by Calnago

Ouch!! I cringe when I see stuff like that... the scoring of the inner carbon from pushing that starnut down. I don’t think that came from the factory that way did it? All the Time Carbon steertubes I’ve ever seen use a close fitting alloy sleeve for support, that stays in place once you snug up the stem. That process “squeezes” the walls of the steertube around the alloy sleeve. Did your stem ever come loose without they sleeve in it. I would think it might as the walls, with that vectran in it, seem kind of soft when compared to the all carbon steertubes in most other forks.
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TMI
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by TMI

Calnago wrote:
Fri Sep 28, 2018 8:12 pm
Ouch!! I cringe when I see stuff like that... the scoring of the inner carbon from pushing that starnut down. I don’t think that came from the factory that way did it?
Yes I believe it did, though I am not the original owner. I found this document that lists the types of starnuts for the Cannondale forks of this era.
http://wodocs.com/docum/541-cannondale_ ... ote-2.html
The KB506 matches what is in my photo.
Calnago wrote:
Fri Sep 28, 2018 8:12 pm
All the Time Carbon steertubes I’ve ever seen use a close fitting alloy sleeve for support, that stays in place once you snug up the stem. That process “squeezes” the walls of the steertube around the alloy sleeve. Did your stem ever come loose without they sleeve in it. I would think it might as the walls, with that vectran in it, seem kind of soft when compared to the all carbon steertubes in most other forks.
I put over 9k miles on the bike without incident, though I was never confident that I had the headset adjusted properly, and I think it gave my LBS mechanic trouble, as well. A slipping starnut is the likely culprit.

Would it be prudent to have the top portion of the steerer tube cut? There is currently about 55mm of steerer above the headset cap.

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Calnago
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by Calnago

The slipping starnut was likely not the culprit. It is very difficult for the starnut to slide back up without digging/cutting even further into the steertube. That’s why I asked about whether the stem would come loose. Without the alloy sleeve, there is nothing to stop the “squeezing” effect of the stem on the relatively soft steertube, and as such it can work loose through riding.
I’m actually dealing with a starnut placement issue right this moment on a Cervelo with an alloy sleeve epoxied into the steertube.

Edit: I just realized that you are using this Time fork in a Cannondale frame. So you will need some kind of compression plug that stays put in order for you to provide the preload on the bearings. Perhaps that’s why the starnut was jammed in there in the past. That is probably not an ideal steertube to be used without the Time alloy insert, but then you wouldn’t have anything to be able to provide the preload. The Time headset preload is applied at the headset, unlike any other manufacturer. I wouldn’t want to be clamping a stem onto that steertube without the proper internal support that is provided by the Time fork insert.
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TMI
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by TMI

Calnago wrote:
Fri Sep 28, 2018 9:15 pm
The slipping starnut was likely not the culprit. It is very difficult for the starnut to slide back up without digging/cutting even further into the steertube. That’s why I asked about whether the stem would come loose. Without the alloy sleeve, there is nothing to stop the “squeezing” effect of the stem on the relatively soft steertube, and as such it can work loose through riding.
I’m actually dealing with a starnut placement issue right this moment on a Cervelo with an alloy sleeve epoxied into the steertube.

Edit: I just realized that you are using this Time fork in a Cannondale frame. So you will need some kind of compression plug that stays put in order for you to provide the preload on the bearings. Perhaps that’s why the starnut was jammed in there in the past. That is probably not an ideal steertube to be used without the Time alloy insert, but then you wouldn’t have anything to be able to provide the preload. The Time headset preload is applied at the headset, unlike any other manufacturer. I wouldn’t want to be clamping a stem onto that steertube without the proper internal support that is provided by the Time fork insert.
This TIME fork was designed for this Cannondale frame. https://www.bikepedia.com/QuickBike/Bik ... item=35248

When did TIME start using vectran in their forks? I don't think this is an issue for the fork I have as I never experienced any loosening of the stem. The original top cap was a beefy alloy piece that fit very snugly into the steerer. No doubt it was intended to reinforce the steerer from the clamping forces of a stem, but it was a bear to remove if one wanted to change stems.

Here is a close-up pic of the fork.
Image

Here is the FSA compression plug I intend to install into the steerer. It's nearly identical to the one I have in the carbon bike I've been riding for three seasons. https://shop.fullspeedahead.com/en/type ... evice-3887
That should provide enough support inside the steerer so that no sort of additional insert is needed.

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Calnago
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by Calnago

Yes it does look like they were using a starnut in some of their carbon steertubes back then. Don’t know of any manufacturer that would be doing that now. All you can do is try it out I suppose. That compression plug you’re planning on using seems as good as any for what you need to do. Especially if the top piece that screws down has an outer diameter that’s a close fit to the inner diameter of the steertube.
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