Carbon Steerer Wear
 

Bought a frame and fork off the fleabay and noticed that the carbon steerer has some grooves on it where it contacts the headset bearings. I don't see any cracking in the carbon but I have never seen a steerer look like this before.https://lh3.googleusercontent.com/-e...930_194552.jpg
https://lh4.googleusercontent.com/-L...930_195113.jpg

What do you think? Rideable?

Is that a groove worn into the carbon? If so, I wouldn't ride it.

I'd say notrideable.

Edit: Nevermind my previous comment. Looked at it on my phone and only saw the top part and not the deep groove. Stay away.

I think it's the epoxy because if it was worn into the carbon there should be broken fibers, right? That being said it is about .1 mm deep.

If it were me, I'd run away as fast as I can. Something like that, no matter how small, is a stress riser, and if you don't have an issue now, you will in the future.
That is into the carbon, from what I can see. Not broken, but they're creased.

What bike is this from? I would absolutely return that to the seller...

I would not ride this myself or allow a friend of loved one to do so.

dave

0.1mm deep? circumferentially?

There is no possible way I'd ride that!

I've seen a few steerer tubes with similar wear marks. Likely cause was a loose headset. I would never ride that fork again.
Things like this don't happen overnight. It's another reason for frequent bike inspections and regular bike breakdowns.

...looks like a ham-fisted "mechanic did a number on that one. NOT rideable, unless you cut below the deep groove and install on bike with short head tube.Lou

Ditto
 

Don't ride it. Is the potential damage from the failure worth the cost of a replacement fork? NO. Maybe think about replacing the headset too, that's not right.

And I'd consider replacing the headset, too. To wear a groove that narrow, the headset would have to have had a sharp edge directly in contact with the steerer. So it could potentially do the same thing to the next for it was in contact with.

This, but who knows if the fork always been like that, the groove is perfect and looks like has been there forever.

What you can do is just cut it below the line and sell it? It is a 1inch colnago fork by any chance?

Some Look forks have a groove much deeper than this for the Headfit circlip...it must be 1mm or more. But I guess they make the the entire steerer with thicker walls to make up for it...

It's a 1.125" fork.

i've seen this. its not cracked but rather suffering from what is called creep. i've also seen it on seat tubes with band clamp FDs that are on the small side for the tube(or visa versa)

essentially the matrix is held in a position contrary to where it was when cured. it will "creep" into that shape or position.

google creep behavior in FRPs(fiber reinforced plastics) if you wanna get all technical

while it may seem ok to ride, you do have distortion in the matrix at a fairly critical point. I'd replace myself.