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I've relocated to a new town so I'm still looking around for good bike shops. For the time being as I was re-assembling my stem, i noticed a small notch of about 0.5mms on the front of my fork (the back side is clean). It is perfectly aligned with stem so I suspect that I was probably riding with a loose (or overtightened) stem at some point, which tbf despite the fact that it is a bit scary, it is not that bad because it indeed looks like a surface scratch.

However, today I thought about checking the fork from the inside just to make sure that this is not a crack, and what I realized was that indeed the stem has pushed the fork so bad that it has created a similar sized extrusion from the inside. The shadow makes it a bit wider that it is, but there is definitely some kind of anomaly there.

As of now I really don't feel safe riding the bike with this fork, and I'll try to get it checked asap, but until then I would like the opinion from some more experienced people.

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  • The most effective fix would be to bypass the compromised section of tube: remove all the spacers and compensate the height with a rising stem, then you can cut off the tube just a little above the crack. This way there wouldn't be much load on it, and even if the crack were to propagate it would not cause the bars to fall off. Mar 2 at 0:06

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This question and the answer will probably help some, and the answer includes photo examples of types of damage. The steerer ring of death photos may be a helpful reference.

In this case, I don’t think that the ridge on the inside was created by impacting the outside. Imagine many sheets of fabric, like your bedsheet or your shirt. Carbon fiber is made of many layers of fabric like that, only thinner and much stronger. It won’t dent all the way through like metal might. You don’t usually expect to fracture it all the way through the steerer wall - if you did, I think the fork would break.

Unfortunately, it does look like a gouge in the surface, which means fibers are broken, which means the entire structure is compromised. This is why we all need to check our headsets for correct preload - if you can spin the spacers, you need more preload. By the way, metal frames could have the bearing seats ovalized, which is also bad. If there’s enough preload, that steerer can last a very long time.

These days, I don’t think a lot of people make third party carbon forks. Whisky Components, Enve, and Wound Up are two names I remember that are still active, with Enve being the premium version. You would want to match your fork’s rake. Also, it looks like your steerer is 1-1/8” straight, which should simplify things. The bike manufacturer may have spares, but this can be expensive. It is possible that a carbon repair shop might be able to bond a new steerer in, although I don’t know how many of them do it and if this is cost effective. You would need to ask around for credible local shops.

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    Thank you for your detailed comment. Since the external impact would not necessarily cause the internal ridge, what do you think caused it? I do have a very decent carbon shop not very close to me but this is my best option I guess. I'll ask for prices. I'll also contact the manufacturer to see how much would it cost. Do you think that the fork at its current state would be safe for indoor riding?
    – Greg
    Mar 1 at 23:05
  • @Greg talk to the carbon shop - they may be able to sleeve the inside with aluminium, and apply a top-filler coat. Or they may recommend replacing the whole steerer tube. Consider the failure risk - your handlebars would disconnect from the bike and your steering control would stop. That would be bad. It looks like some combo of overtighteneing, a possible ridge on the inside of the stem, and plastic-deformation of the CF binder. Temporary workaround is to move some spacers from below to above the stem, but you'll likely develop a second trench/ridge lower down.
    – Criggie
    Mar 2 at 22:46
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    @Criggie thanks for the recommendation. Spoke to the carbon shop, they said that when it comes to serious damage on carbon fork, they always recommend a replacement :/ So I guess that's what I got to do now :(
    – Greg
    Mar 6 at 13:41

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