Best to ask the local engineering company to make you one up 😉 piece of cake with the right kit and skill!

I used a friction fit as mine was fine without the extension, this just made sure I could tighten the top clamp bolt correctly and not cause the stem to fracture by pinching the clamp till the gap closed.

Machine screws are not a good solution, epoxy glue is fine but you need to do it properly with a small clearance for the glue layer and the surfaces must be prepared properly etc.

If in doubt, dont.

I have successfully pressed out an old steerer tube and fitted a longer one. Cooled the whole top assembly in a freezer then heated the aluminum crown casting with a heat gun keeping the steerer tube as cool as poss then pressed out in a vice. Use a cutting of suitable size pipe to allow the steerer to push through the crown. Same in reverse to fit the new steerer tube. Heat expands the one where the cold contracts the other to give minimal resistance. You could likley do the same with the above mentioned bung to give maximum friction fit.

I Used the forks for years with no issues.

njee20, yes I WOULDN’T!

Machine screws are not a good solution, epoxy glue is fine but you need to do it properly with a small clearance for the glue layer and the surfaces must be prepared properly etc.

If you are relying on friction alone i can’t see why machine screws combined with friction fit are a bad idea? A couple of small holes in the steerer won’t weaken it noticeably especially at the top, wouldn’t think of it down near the crown where maximum forces will be in action.

At least if you ever wanted to remove it you could screw out the machine screws and push it out. Not so easy if it is epoxied in.

it does not rely on friction alone , the part that inserts into the steerer is also clamped by the lower stem pinch bolt.

I rode it without the extension as well and the stem did not slip before I did this.