Hey folks - I just put together a new carbon fork on my road bike.

It's my first full carbon fork - it came with an expansion plug which was straightforward enough, but it also had this thin aluminum sleeve, split lengthwise, with the expansion plug.

I played around with it, but couldn't figure out how to use it - I assume it is for steerer tubes with a little larger inside diameter than mine.

I assembled the fork without it - it feels solid enough that way, and I'll do a shakedown ride tomorrow to see how it goes, but I thought I'd check with the helpful crew here on BF - is this an optional part?

Was the sleeve included in the package with the expansion plug or did you buy a stem also? It's possibly a shim to allow a 1-1/8" stem to fit a 1" steerer and a lot of 1-1/8" stems come with them.

it was packaged together with the plug - wrapped up in plastic and taped to the fork.

it was less than 1 mm thick, so i doubt it was the shim you speak of - silver aluminum, textured coating - looked like something to help the expansion plug "bite" - but I'll be damned if I could figure out how to use it with my fork ....

Once the fork, headset and stem are assembled the plug and cap serve no purpose except to fill the hole on top of the steerer. The purpose of the plug is put a little preload on the headset bearings before you tighten the stem. You could take out the plug and ride thousands of miles or until there was a need to readjust the headset preload. One time I bought a stem at a swap meet and wanted to try it out on my ride back home. It wasn't quite as tall as the old stem so the cap did not bear down on it to set preload and nobody there had spacers. I enlisted the help of a friend to push down on the bars and stem as hard as he could and tightened the stem -- no problem.

Bottom line: if your headset is not loose you are OK.

Don in Austin

Maybe your original guess was correct that it's there to allow the plug to be used in steerers with a larger ID, say Cr-Mo instead of carbon. I know Profile Designs sold expander plugs in different OD's for use in various steerer materials and the ones for Cr-Mo steerers were larger.

I used one of their steel steerer expanders in my Surly Cross Check as an adjuster until I determined exactly where I wanted to cut the steerer and then replaced it with a starnut.

Another use Is when the steel steerer was cut too short ,
you can get a steel tube stem raiser to bring the bars up on threadless steerers too.
it uses a Quill to secure it, so the expansion plug is removable,
to Re-tighten the quill bolt , later, or remove it.
and then the spacers under the stem cover up the addition, fine..

Clarification - I assembled the fork WITH the expansion plug (which was logical and I fifired it out)

What confused me was that flimsy sleeve the same length as the plug, split down the entire length.

I didn't use it. Going out for a shakedown ride. I'll see how it works out!

Would be better if you post a picture of the parts, some expansion plugs work backwards and use something like a sleeve. My BMC comes with one that is so weird and use a darn sleeve also. Is the sleeve knuckled around???

I think I'm good. No headset/fork issues on a deliberately bumpy, twisty ride.

The sleeve, and I'm just calling it that for lack of a better term was thin, and cut/split along the entire length, as if to accommodate various diameters. Coupling it with the plug I got with the fork was out of the question - the both wouldn't fit in any way that makes sense to me. I really think it's designed to fit over the plug and help fill in the gap on a larger ID steerer tube than the one I bought. Not sure why it shipped with the fork though. No biggie - my bike is good to go now.

Probably a generic plug and set up to match whatever steerer it happens to be used with.

my full carbon fork came with a cheap (they are really just a couple of cartridge bearings and a spacer) NECO headset. it has one of those. the outside of it is knurled and digs into the softer carbon, sort of like a star nut. once installed it isn't removed easily. here's a pic of something similar.



if slide over and up the plug before installation it will expand as the plug is tightened, but if all is well, well... i guess it isn't necessary.

It is something like this???