Warzoid

I have a pic of this but cant post it until i have 10 posts so ill try to explain

I have a carbon fork with alloy steerer.

I thought the steerer was bent but after closer look its actually comming out of an other alluminum tube thats bonded inside the carbon with a plastic thing between the 2 aluminum parts.

Is there any way to press the steerer tube back in?

DiabloScott

I think you're describing a press fit steer tube inside an aluminum fork crown. I don't think I could ever trust it again.

WizardOfBoz

Upload your pic to google pics and post the url here if you want.

But I agree with old El Diablo: If the alloy steerer was a press-fit and it's now loose it would be a bad idea to trust it.

AnkleWork

How do you know it's coming out?

alcjphil

This is a very vague description. However, if your steer tube is coming out of the fork crown your fork is severely compromised. Pressing it back in will not solve the problem.
You need a new fork

davidad

Do not ride on that fork. Take it to the dealer and see if it is covered.

Wilfred Laurier

From your description, I would give you 50/50 odds that it will fully separate while riding.

Separating while riding WILL 100% result in you getting seriously injured. How do those odds sound?

HillRider

You need a new fork. End of discussion.

Andrew R Stewart 

Often these failures are "hidden" during riding by the ft brake mounting bolt acting as a bolt keeping the, loose in crown, steerer from coming out. Remove the ft brake and watch out!. Andy

dddd

I've definitely never seen or heard of an alloy steerer connected to a fork crown with any sort of plastic interface.

Pic's or it didn't happen!

CliffordK

@Warzoid's Album:

https://www.bikeforums.net/g/user/507458
https://www.bikeforums.net/g/album/15541797



This appears to be @Warzoid's other thread.

need help with fork replacement
Bought a 2004 Devinci apex bike with full tiagra

CliffordK

That is an absolutely bizarre fork.

I have to agree with others. Time to send it to the great trash bin in the sky, and source a new fork.

All forks tend to have a slightly raised part for the crown race seat. But, that appears to be larger than I would otherwise expect.

I'd measure the bearing seat and steer tube carefully. Is it possible that that is a pseudo 1 1/4 x 1 1/8 tapered fork?

Here are the dimensions of the tubes and the crown race.
https://www.sheldonbrown.com/cribsheet-headsets.html

CliffordK

Looking at your photo, that construction looks odd. But, I'm not sure that is the correct interpretation.

I'd go ahead and pull off the lower crown race so you can get a good look at the construction (and you will probably want it when you replace the fork.

What I'm wondering is if the inner 1 1/8" steer tube goes the whole length into the fork.

The outer sleeve may only be a short stub of 1 1/4" sleeve stub.

Thus the outer sleeve & piece of plastic may simply be on the frame to hold the crown race and lower bearing in place. It may not be significantly structural at all.

Your fork does look like it may well be bent.

The interpretation is likely the same, new fork. But, you need to measure what you have carefully to get the right one.

Wilfred Laurier

I also can't tell what's going on with that for, except for that it should not be used. Even if it is not separating, the steerer tube is clearly not parallel to the bearing seat.

WizardOfBoz

I agree with Clifford:
1) That fork is bizarre,
and with Clifford and Wilfred:
2) That fork is toast. Dangerous. Don't ride with it.

I believe that the design is inherently flawed. You are depending upon the steer-tube for rigidity. And at the base of that tube, at the worst spot imaginable, is a press fit joint. A joint WITH A PLASTIC BUSHING. Now, I like plastics. I'm a chemical engineer and did underrad research on plastics. I worked for DuPont where we made Teflon(R) and Zytel(R) plastics. But 1) that joint shouldn't be there, and 2) if its an interference fit, there shouldn't be any material with a lower modulus between the two parts (the fork and aluminum socket, and the top part of the tube. It makes the joint weaker.

Further, adjusting the preload on the headset bearings induces tension on that joint. The OP (or a previous owner) likely overtorqued the preload bolt which pulled the tube out of the fork head. Even without the other design flaws, this setup should be keyed so that you can't pull the tube out with over-aggressive preload.

Design is bad enough, and dangerous enough so that the OP, I believe, should go back to the mfr and ask for a proper fork. In any case, that fork should be replaced

WizardOfBoz

Re-reading Clifford's note prompted a question*. Can you pull that tube out of the fork? How far down did it extend? Was it drilled to allow the brake mounting bolt to act as a key? The tube looks like it was swaged down (or necked down). How long is the smaller diameter part of the tube? Was the fork precision bored to accept that tube? Last, the OP states that the steerer is alloy. Are we sure? The surface finish looks like plated steel. Check with a magnet.

If you remove the brake, you may be able to pull the tube out.

* I guess a lot of questions....

caloso

That looks hella sketch, as the kids would say.

AnkleWork

Another non-conversation.

Warzoid

dont worry guys i already changed my fork this one on the picture is in the trash

Andrew R Stewart 

Warzoid- Maybe you should have kept quite and let us go on ad infinitum Good decision though, to replace the fork. It would have been interesting to see a sectioned cut through the steerer/crown. Andy

WizardOfBoz

Awwwww. Yeah.

Seriously, I would have liked to see the design of the polymer-assisted interference fit.