Carbon steerer w/ star nut?

[FastforaSlowGuy]

Pulled out a fork I got recently, and someone installed a star nut instead of a compression plug. There's gouging down the inner walls of the steerer tube. I know that's bad, but can I just tap it down deeper, install a compression plug, and call it a day? Has the gouging made this a toasted fork? For now, I will just build it up and stick it on the trainer, but I'm trying to decide if I need to source a new fork.

[robt57]

Some that use the star in carbon used an alloy or even an heavy clear vinyl tube. I'd consider getting it out and J/B welding a tube of ti or alloy with an star nut still in it if it is any kind of desirable fork. Else sell it to someone with, or use it on short Head Tube small frame with the nasty bi cut off.

My Premium Plus fork is on a 56 now, I got it damaged on a 60 CM frame and cut it down to get ride of the nasty bit and then some...

[Mark McM]

What brand of fork is it?

Some brands of carbon fork are actually designed to be used with a star nut. In particular, Cannondale carbon forks often use a star nut.

Also, can we assume that that the fork does not a (metal) insert bonded into it? Many bonded in inserts also use star nuts.

If the fork is not intended for a star nut, you should probably not use it, unless you can cut off the steerer below the star nut. Tapping the star nut deeper will just increase length of the steerer that is gouged and weakened.

[FastforaSlowGuy]

Cannondale fork. Did they use a star nut? I thought they all used a compression plug other than the true temper forms with that bonded sleeve thing.


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[oliver1850]

I would not drive it down any deeper than it is now. If it's not any deeper than the middle of the stem clamp, I'd drill/dremel the star nut out. I would want to avoid having star nut gouges below the mid point of the stem clamp, and especially right at the bottom of the stem and immediately below. If there are spacers under the stem now, all the better. Mount a stem with a bit more rise below the area where the star nut was.

[Mark McM]

Cannondale fork. Did they use a star nut? I thought they all used a compression plug other than the true temper forms with that bonded sleeve thing.

I don't have the entire list of Cannondale forks that used star nuts, but just as examples, here's some documentation from Cannondale from installing star nuts in Slice and SystemSix forks:

https://www.cannondale.com/-/media/files/manual-uploads/manuals/2004_slice_carbon_fork_topcap_starnut_technote_en. pdf

https://www.cannondale.com/-/media/files/manual-uploads/manuals/2006_system6_owners_manual_supplement_en.pdf

[hollowgram5]

My 60cm SystemSix has a star and the tall/long top cap that sleeves into the steerer for the stem clamp load to rest on.

I've been riding it for nearly a decade, and it's from 07/08 production.. I'm also not a featherweight but everyone's experience is different.

[robt57]

Cannondale on those if memory serve should have no spacer above the stem. And I think like Trek the stem should not have less than 10mm from the opening inside stem to the top or bottom of the stem stack.

[FastforaSlowGuy]

I'll give C'dale a call on Monday, but I see some folks have "drilled out" the star nut and used an expander. This may be a stupid question, but how does one drill out the star nut?

[Charles M]

I'll give C'dale a call on Monday, but I see some folks have "drilled out" the star nut and used an expander. This may be a stupid question, but how does one drill out the star nut?

with a... yep :)

You just have to get the solid part out and the fins will pull out afterward. The starnut forms a nice pocket for the bit...

[robt57]

If the bit grabs and spins the entire nut, kiss the fork goodbye. I think it more likely the middle threaded bit would spin in the springy star portions and you'd get nowhere fast. But never tried it myself.

I'd take a super close look at the rest of the fork and steerer for anything remotely suspect that should make you move on to another fork as well.

I just never get used carbon forks anymore. And my Strong road bike made in 2000, is on a steel fork after all the yanking and banking a younger me did for 12 years straight.

I'd see the smallest of a crease or notch and wife's bike got a new [my used once new] carbon fork with the suspect portion cut off being she rides 10CM smaller bike that me.

But I just ordered a Wound up for 1/2 off.

[GregL]

I'll give C'dale a call on Monday, but I see some folks have "drilled out" the star nut and used an expander. This may be a stupid question, but how does one drill out the star nut?
Very carefully...:) I drilled out the star nut in one of my Cannondale carbon steerer forks. The fork in question was the much sought-after Slice Premium fork that came on my 2007 Six13 Team frame. These forks have a larger inner diameter than other 1 1/8” carbon forks. My fork did not come with the correct top cap, so I elected to use an expander plug. I solicited advice from the best machinist at my company. He had me wrap the fork in a soft, padded cloth and gently hold it in a vice. I then used a sharp drill bit just slightly larger than the inner diameter of the star nut threaded hole for the first drilling. After the first drilling, I used successively larger drill bits for each drilling. After several drillings, the star nut simply fell apart. This method ensured that the drill bits would not grab the star nut and spin it inside the steerer.

Greg

[robt57]

Very carefully...:) much sought-after Slice Premium fork that came on my 2007 Six13 Team frame.

Greg


Mine is too, it got cut and moved from a 60CM 6/13 to a 56 CADD 5 after I cut the crushed top. Seems the CADO plug for the wrong fork was used and the air space allowed the crush. That friend got a Ritchey torque tool for x-mas soon after from me. ;)

It till has the wrong top cap, but with a shim that makes it fit perfectly. It is a nice fork to roll IMO.

[GregL]

Mine is too, it got cut and moved from a 60CM 6/13 to a 56 CADD 5 after I cut the crushed top. Seems the CADO plug for the wrong fork was used and the air space allowed the crush. That friend got a Ritchey torque tool for x-mas soon after from me. ;)

It till has the wrong top cap, but with a shim that makes it fit perfectly. It is a nice fork to roll IMO.
I used a shim for a while too, but kept looking for an expander plug that had enough adjustability to fit the steerer’s oversized ID. The KCNC expander plug from Fairwheel Bikes (https://fairwheelbikes.com/kcnc-expander-plug/) works perfectly. I agree that the Slice Premium fork is a great ride. Best fork I’ve ridden on a Cannondale road bike thus far.

Greg