Slipping nut in carbon steerer tube

[Michael]

I posted recently about a loose headset that I couldn't tighten... turned out that the star-fangled
nut in the steerer tube had slipped and tightening the top cap bolt had just drawn the nut up to the
bottom of the top cap, so tightening wasn't drawing all the headset components together.

My LBS pushed the nut back down the steerer and got the headset nice and tight. But now after just a
few rides it's come loose again. I suspect the nut has slipped again. It's a long drive to the LBS,
so I'd like to fix this myself.

How do you tighten this nut? Is there anything special about tightening it in a carbon steerer tube?

Thanks, Michael

 

[Phil Brown]

>My LBS pushed the nut back down the steerer and got the headset nice and tight. But now after just
>a few rides it's come loose again. I suspect the nut has slipped again. It's a long drive to the
>LBS, so I'd like to fix this myself.
>
>How do you tighten this nut? Is there anything special about tightening it in a carbon
>steerer tube?

Typically star fangled nuts are not used with carbon steerers because they tend to damage them. A
wedge expander is more common. Phil Brown

 

[Sheldon Brown]

Michael wrote:

> I posted recently about a loose headset that I couldn't tighten... turned out that the
> star-fangled nut in the steerer tube had slipped and tightening the top cap bolt had just drawn
> the nut up to the bottom of the top cap, so tightening wasn't drawing all the headset components
> together.
>
> My LBS pushed the nut back down the steerer and got the headset nice and tight. But now after just
> a few rides it's come loose again. I suspect the nut has slipped again. It's a long drive to the
> LBS, so I'd like to fix this myself.
>
> How do you tighten this nut? Is there anything special about tightening it in a carbon
> steerer tube?

YES! You should NEVER use a star-fangled nut in a carbon steerer! It's liable to damage the steerer
and lead to catastrophic failure.

Forks with carbon steerers generally come with some sort of expansion plug to use in lieu of a star
nut. The star nuts have sharp edges which can damage the inside of the steerer.

Sheldon "DANGER! DANGER! DANGER!" Brown +--------------------------------------------------+
| If you find yourself standing to accelerate, |
| on level ground, it is a sign that your gear |
| is too high, or that your saddle is too low. |
| See: http://sheldonbrown.com/standing.html |
+--------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Bill]

"Michael" <[email protected]> wrote in message
news:[email protected]...
> I posted recently about a loose headset that I couldn't tighten... turned out that the
> star-fangled nut in the steerer tube had slipped and tightening the top cap bolt had just drawn
> the nut up to the bottom of the top cap, so tightening wasn't drawing all the headset components
> together.
>
> My LBS pushed the nut back down the steerer and got the headset nice and tight. But now after just
> a few rides it's come loose again. I suspect the nut has slipped again. It's a long drive to the
> LBS, so I'd like to fix this myself.

>
> How do you tighten this nut? Is there anything special about tightening it in a carbon
> steerer tube?
>
> Thanks, Michael

Are you sure you don't have an expanding wedge that is not properly tightened or possibly has a
little lube on it that is causing it to slip? Something like this http://www.biketoolsetc.com/index-
.cgi?id=859065314891&c=Repair%20Parts&sc=Headset&tc=Compressor%20Plug

If you really have a star nut in a carbon steerer then you should take it to a real bike shop and
never look back.

Bill

 

[Dan Brussee]

On Tue, 25 Nov 2003 11:43:38 -0500, Sheldon Brown <[email protected]> wrote:

>Michael wrote:
>
>> I posted recently about a loose headset that I couldn't tighten... turned out that the
>> star-fangled nut in the steerer tube had slipped and tightening the top cap bolt had just drawn
>> the nut up to the bottom of the top cap, so tightening wasn't drawing all the headset components
>> together.
>>
>> My LBS pushed the nut back down the steerer and got the headset nice and tight. But now after
>> just a few rides it's come loose again. I suspect the nut has slipped again. It's a long drive to
>> the LBS, so I'd like to fix this myself.
>>
>> How do you tighten this nut? Is there anything special about tightening it in a carbon
>> steerer tube?
>
>YES! You should NEVER use a star-fangled nut in a carbon steerer! It's liable to damage the steerer
>and lead to catastrophic failure.
>
>Forks with carbon steerers generally come with some sort of expansion plug to use in lieu of a star
>nut. The star nuts have sharp edges which can damage the inside of the steerer.
>

Ok, Ive wondered this since I first heard of the star nut. Why not use an expansion plug on steel or
aluminum too? The slightly higher cost of the part would most surely be offset by the simplicity of
installation and the possibility of a screwed fork if done incorrectly.

 

[Scott Hendricks]

[email protected] (Michael) wrote in message
news:<[email protected]>...
> I posted recently about a loose headset that I couldn't tighten... turned out that the
> star-fangled nut in the steerer tube had slipped and tightening the top cap bolt had just drawn
> the nut up to the bottom of the top cap, so tightening wasn't drawing all the headset components
> together.
>
> My LBS pushed the nut back down the steerer and got the headset nice and tight. But now after just
> a few rides it's come loose again. I suspect the nut has slipped again. It's a long drive to the
> LBS, so I'd like to fix this myself.
>
> How do you tighten this nut? Is there anything special about tightening it in a carbon
> steerer tube?
>
> Thanks, Michael

One, once you've got the headset tight, the stem should hold everything snug even if you take the
top cap off. If you've tightened the stem and it's still slipping, it's not the star-nut that's
causing your problem.

And, B, try an expansion doo-hickey like Reynolds supplies with their carbon steerer-tubed forks.
Won't slip.

S.

 

[Richard Chan]

[email protected] (Michael) wrote in message
news:<[email protected]>...
> I posted recently about a loose headset that I couldn't tighten... turned out that the
> star-fangled nut in the steerer tube had slipped and tightening the top cap bolt had just drawn
> the nut up to the bottom of the top cap, so tightening wasn't drawing all the headset components
> together.
>
> My LBS pushed the nut back down the steerer and got the headset nice and tight. But now after just
> a few rides it's come loose again. I suspect the nut has slipped again. It's a long drive to the
> LBS, so I'd like to fix this myself.
>
> How do you tighten this nut? Is there anything special about tightening it in a carbon
> steerer tube?

Before the sharp edges of the star nut cut up the inside of the steerer, get the correct setup.
Assuming you have the 1 1/8" steerer, there are bike shops that sell the expander plug that goes
into carbon steerers.

Hint: how tight are you tightening your bolt? Don't use the same methodology you used with threaded
stems. The two bolts that clamp onto the steerer help to lock the stem, not the top bolt. Even with
that, don't muscle it and crack the steerer.

 

[M-Gineering Imp]

Scott Hendricks wrote:

> One, once you've got the headset tight, the stem should hold everything snug even if you take the
> top cap off. If you've tightened the stem and it's still slipping, it's not the star-nut that's
> causing your problem.

correct: it could be the steerer-crown glue joint coming apart!
--
Marten

 

[Sheldon Brown]

>>>How do you tighten this nut? Is there anything special about tightening it in a carbon
>>>steerer tube?

I replied:

>>YES! You should NEVER use a star-fangled nut in a carbon steerer! It's liable to damage the
>>steerer and lead to catastrophic failure.
>>
>>Forks with carbon steerers generally come with some sort of expansion plug to use in lieu of a
>>star nut. The star nuts have sharp edges which can damage the inside of the steerer.

Dan Brussee asked:

> Ok, Ive wondered this since I first heard of the star nut. Why not use an expansion plug on steel
> or aluminum too? The slightly higher cost of the part would most surely be offset by the
> simplicity of installation and the possibility of a screwed fork if done incorrectly.

That's one way to go. On my new IRO fixed gear bike, I installed a Winwood plastic fork, but went
with the version with the aluminum steerer. (I'm not brave enough for plastic steerers.)

To save a few vitally important grams, I installed it with no star nut nor top cap, just pushed the
stem down hard on the steerer by hand and tightened the binder bolts. The open-top steerer provides
a handy extra storage space...

The headset adjustment seems just fine, but I don't think I'm ready to do this on a customer's bike.

Sheldon "Weight Weenie" Brown +----------------------------------------------+
| My mind is aglow with whirling, transient | nodes of thought careening through a cosmic | vapor
| of invention! --Mel Brooks |
+----------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone
617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Robert Brown]

Michael wrote:

> I posted recently about a loose headset that I couldn't tighten... turned out that the
> star-fangled nut in the steerer tube had slipped and tightening the top cap bolt had just drawn
> the nut up to the bottom of the top cap, so tightening wasn't drawing all the headset components
> together.
>
> My LBS pushed the nut back down the steerer and got the headset nice and tight. But now after just
> a few rides it's come loose again. I suspect the nut has slipped again. It's a long drive to the
> LBS, so I'd like to fix this myself.
>
> How do you tighten this nut? Is there anything special about tightening it in a carbon
> steerer tube?
>
> Thanks, Michael

Could be an issue with method used?

Just to confirm your work (pls excuse this if you are indeed very familiar with how a-heads
function):

To tighten:
1. Handlebar stem binder bolts backed off
2. Star nut properly down the steerer tube (though star nut kind of dangerous in a carbon tube)
3. Tighten top cap bolt to eliminate headset play. If the h'bar stem does not move freely down the
steerer tube while doing this, you may consider twisting the handlebars back and forth ever so
slightly, in relation to the forks, to allow the stem to creep down the steerer tube while
tightening top cap bolt.
4. Tighten h'bar stem binder bolts once handlebars are aligned with wheel/fork.
5. Loosen top cap bolt so that it is no longer stressed.
6. Ride like hell.

The basic principle is that once the binder bolts of the handlebar stem are tightened (and the
headset has close to no play), it should be possible to back off the top cap bolt so that it is
slightly more than finger tight (if fingers could've reached it). What holds the tension in the
headset is the stem secured to the steerer tube. It should not move at all until you loosen the
binder bolts. The top cap and its bolt should play no further part in the game, until next time you
want to readjust the headset or remove the h'bar stem.

If all is working well it should be possible to ride without top cap and bolt at all, once
everything's tight (though it looks better with them on).

If you cannot get sufficient tightness on the h'bar stem via the binder bolts (so that the stem
starts slipping slowly up the tube, causing headset bearing play), then that problem should be
addressed *without* using the top cap and its bolt as support. In my case (Deda Zero 1 inch stem on
steel steerer tube), I used a small amount of masking tape on the inside of the stem and that
stopped the stem from creeping up the steerer tube. Inelegant, but effective.

BTW you should have no grease in the mating surfaces between steerer tube and h'bar stem.

/Robert Sweden (Colnago Chic, Campag veloce, does not grease tapers on centre bracket axle ;-)

 

[Qui Si Parla Ca]

michael-<< I posted recently about a loose headset that I couldn't tighten... turned out that the
star-fangled nut in the steerer tube had slipped and tightening the top cap bolt had just drawn the
nut up to the bottom of the top cap, >><BR><BR>

I HOPE that you don't have a geniune star fangled nut inside a carbon steerer. If you do, shame on
the bike shop as this is really STOOPID!! Can cause a steerer failure.

BUT, the nut or insert is there to adjust the HS. Once accomplished with the stem tight, the top cap
can be throw away. Your HS loosening is NOT due to this nut/insert moving up the tube. I suspect
perhaps the headtube may need to be faced or the HS cups need to be removed,, ionsrpected and
re-installed.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

[Bruni]

Has anyone on list used the Time Microset adjustable spacer? I tried one on a carbon fork not ready
to be cut and I love everything but the price. Tom

--
Bruni Bicycles "Where art meets science" brunibicycles.com
410.426.3420 Qui si parla Campagnolo <[email protected]> wrote in message
news:[email protected]...
> michael-<< I posted recently about a loose headset that I couldn't
tighten...
> turned out that the star-fangled nut in the steerer tube had slipped and tightening the top cap
> bolt had just drawn the nut up to the bottom of the top cap, >><BR><BR>
>
> I HOPE that you don't have a geniune star fangled nut inside a carbon
steerer.
> If you do, shame on the bike shop as this is really STOOPID!! Can cause a steerer failure.
>
> BUT, the nut or insert is there to adjust the HS. Once accomplished with
the
> stem tight, the top cap can be throw away. Your HS loosening is NOT due to
this
> nut/insert moving up the tube. I suspect perhaps the headtube may need to
be
> faced or the HS cups need to be removed,, ionsrpected and re-installed.
>
> Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
> (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

[Jasper Janssen]

On Wed, 26 Nov 2003 08:32:47 +0100, M-Gineering import & framebouw <"kijk maar op m-gineering.nl als
je het echt wil"@wet.en> wrote:

>correct: it could be the steerer-crown glue joint coming apart!

That looks painful.

Jasper