removing a zinn insert from a carbon steerer tube

[boomforeal]

i bought a used frameset last year. the original owner had epoxied a zinn aluminum insert into the steerer tube of the fork, like this one:

https://www.cornercycle.com/about/carbon-fork-insert-pg69.htm

last week i pulled the front end apart to check the headset bearings and clean the cups (its been a dusty summer). found that the insert had pulled up and out of the steerer tube by a 1/4"

this seemed to suggest that the bond of the epoxy holding it in place had broken, so i figured i would pull it out and either rebond or replace

stacked several spacers on top of the stem and started using a top cap and bolt to pull the insert out. worked fine for about 1.5" and then the insert refused to budge any further; rounded the bolt head with my park alan wrench at which point i decided to stop and regroup

any ideas what could be preventing the insert from moving any further after not protesting for the first inch plus, or tips on getting it out? i'm a pretty confident wrench but this is my first carbon steerer tube so i don't have much relevant experience to draw from

thanks

[m_sasso]

Have you completely loosened off the stem clamp bolts?

[boomforeal]

Have you completely loosened off the stem clamp bolts?

yes

[robt57]

heat gun

[glepore]

You pulled it up and the epoxy residue came with it until it wedged itself solid. Heat might work, but it might also weaken the epoxy matrix in the steerer. We need input from someone who builds these forks (ahem) as to what would be safe to break the logjam.

[pdmtong]

You pulled it up and the epoxy residue came with it until it wedged itself solid. Heat might work, but it might also weaken the epoxy matrix in the steerer. We need input from someone who builds these forks (ahem) as to what would be safe to break the logjam.
I would think this is the case so couldn't you get a wood block on top and gently pound it back down and try to pull it out again...the re-insertion acting to break up the wedged residue?

actually, why bother removing the insert if you are ok running the X2 and the bar drop/reach is ok? that insert is not mandatory structural like the alpha Q is so I would also thing it's ok to leave it in there no epoxy.

[Dave]

I would take the fork off the bike and try using a slide hammer.

[Peter P.]

Why not contact Lennard Zinn (https://zinncycles.com/contact/)? I'm sure he's had experience with such work.

[cuda]

here is my 2cents.
try putting some white grease on the insert and push it back in and then repeat what you did with the stem cap bolt. More than likely some of the old epoxy was skimmed off while pulling the insert up and has narrowed the steerer tube. Pushing it back in may free that up. The grease that gets in should make it easier to pull it back out again.

[ergott]

heat gun

I'd try the opposite. The aluminium will shrink more than the carbon if iced.

[robt57]

I'd try the opposite. The aluminium will shrink more than the carbon if iced.

Easy enough to try that first.

[Veloo]

A heat gun can be too uncontrollable.
If you have a decent hair dryer, that may be enough heat without actually burning anything.

To do the cooling, you can try the air duster in a can thing. We used this method in electronics often.
Here's one example.
https://www.youtube.com/watch?v=yaNFNe7qobg

Wonder if both would be that much more effective. You may need a helper you you try both at the same time.

[boomforeal]

thanks all. Some sound and creative ideas here, exactly what I was hoping for. Going to try a few of them and will report back re. results

[prototoast]

Don't use a heat gun, it could just as easily weaken the epoxy you like as the epoxy you don't.

Are you twisting or just pulling? Twisting is the easiest way to break a bond like that, in my experience.