tNuvolari

I have a 2006 Wilier Triestina Izoard(carbon fiber fork & steerer) and I bought a Cinelli/Columbus 1 1/8" expansion plug which I assumed would fit but it it too big to slide in (that's what she said!). Anyway, it doesn't fit despite the fact that the outer measurement of the fork is 1 1/8" or about 28.5mm. The interior measures about 22mm. The Cinelli plug is 23mm at its smallest so no way it will fit. The plug comes with identifying info that says "23-25mm." They also make a plug for 1" steerer but I can't find the Cinelli info that specifies the exact sizing. It only states the 1" model is made for their 1" Minimal fork so not sure if that is a specific fitment for that fork.

So what's going on with this fork? It came with a very small FSA plug which is only about 20mm long whereas the Cinelli is 40mm and provides full support for the steerer tube to counter the full stem clamping length.
I assume the measurement of the steerer is the outer dimension, correct? So why doesn't it fit? And will the 1" version fit or be too small?
I ordered the 1" version tonight but now thinking it's incorrect so still time to cancel.

tNuvolari

https://www.universalcycles.com/shop...s.php?id=17005

HillRider

The plug that came with the fork should be adequate.

DaveSSS 

Your steering tube has a smaller ID than most. I have the cut offs from my low-level Colnago c-rs frames and my Cinelli superstar frames - all made in Taiwan. The ID is 23.6mm on all of them. Nothing wrong with the fsa plug, just don't get carried away when tightening the bolts.

tNuvolari

My frame is made in Italy but the fork is made by Advanced Composites. I guess a thicker fork tube is good in the long run as it must be stronger. I used the FSA plug for a few days but I had already ordered the smaller Cinelli 1" plug which I received today so I installed that. It's not much wider than the FSA but it lines up better with where I have my stem clamped so I think it's better. Plus, it has a nice Columbus dove on it!
I'm kidding as I see how any plug provides support since the fork is pretty stiff and stable so as long as there's something in there to provide a little support, things should be ok.





The new bike at the beach a couple of days ago! You have to love SoCal for the good parts like this even if I'm a true east coaster at heart!

DaveSSS 

I'm surprised that a 1" plug would expand enough to anchor firmly in a 1-1/8" steering tube.

tNuvolari

I know, I wasn't sure it would work either and I didn't have to expand it excessively either. The ID of my steerer was around 22mm and the thickness of the steerer tube is about 4mm (maybe a little less as it all adds up to 29mm or 1 1/8") which is pretty thick, I guess.

Anyway, it fits as did the FSA and I don't think the fitment is overly critical as long as it's in there and torqued appropriately, along with the stem bolts. I torqued it to about 6nm as it's slightly wider and the torque required to overcome the expansion was much higher than on the FSA due to the fact that the Cinelli must expand the metal while the FSA only needs to expand a rubber O ring. My stem says 5nm so I went with that.

Thanks for the help and guidance regarding all of this.

tNuvolari

Oh, is carbon paste needed here? How about inside the steerer tube where the expansion plug sits? It all seems to grip pretty securely without any paste so maybe it's not as critical here as in the seat post.

blamester

The stem holds the headset in place not the plug. So it shouldn't be nessecary.
The plug offers very little if any support to the steerer. It is only there to pull the headset together before you tighten the stem bolts.
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DaveSSS 

The plug must have enough resistance to pull out to allow proper preloading for modern angular contact bearings. If the bearings are not adequately preloaded, road vibrations will ruin them quickly. Some weight weenies even remove the top cap and plug after tightening the stem clamp bolts.