Hi,
Looking for thoughts on this.
Bubbles appearing under the paint of a carbon fiber fork. Is this just cosmetic or is it a structural issue?
Leave as is it'll be grand or new fork/bike needed?
Bike is a 2012 Kona Honky Inc steel frame/carbon fork https://99spokes.com/en-EU/bikes/kona/2012/honky-inc
Cheers
by Sar-War
25 Comments
I would say thats a steel fork with corrosion- but i am not an expert:)
how sure are you that this is carbon?
If that is a carbon fork it’s a steel crown with carbon blades bonded on because that paint bubbling is textbook rust under the paint.
Sorry, but to me this does not look like a carbon fork. To me it’s just a rusty fork, check the mounting hole where no paint is applied – you should see steel there.
Carbon fiber don’t do this but steel does
Exactly what corrosion under paint looks like.
Test it with a fridge magnet, if it sticks it’s steel
Use a magnet. I think it’s steel.
Use a magnet. I think it’s steel.
It corrosion but it likely isn’t steel like everyone else has said. Cheaper carbon forks use aluminium crowns and steerers. I used to service bike to sell and also worked in a bike shop for two years. Never heard of steel/carbon fork, always aluminium/carbon.
That ain’t carbon, brotha.
Are you familiar with corrosive sweat? Some people have sweat that destroys bicycles, and I believe that is what we are seeing here. If I’m correct there will be evidence of that in other places on the bike such as the headset and spacers.
It is not rust under the paint, but salty sweat had gotten under there.
This is pretty rare, but I’ve seen it many times. I’m not aware of a solution, but bikes of these owners need a lot more maintenance than normal.
Is your fork ok? Probably, but you really need to do what you can to prevent additional corrosion.
If it’s steel you can check with a magnet
That ain’t carbon, at least not the entire fork.
That’s steel with rust underneath the paint
That is not carbon fiber.
My guess is the steerer tube and crown is steel and only the legs of the fork are carbon.
Carbon forks with metal steerer/crown. Galvanic corrosion under the paint. Might be fine, might be a deathtrap.
Looks like the Alu crown in the fork is corroded. If you scrape the paint at that point and its chalky white, thats what’s going on.
I’d replace this fork if it were my bike. When the alu crown does this it causes the carbon laminate to seperate front the alu section of the fork, inevitably causing a failure
Thats not carbon
This is a high stress area of the fork and needs to be inspected, regardless of whether or not it’s all carbon or a metal crown with carbon legs. I’d note that a lot of the bonded forks from yesteryear haven’t held up very well and there have been a number of recalls over the years.
It’s likely an aluminum crown and steerer with carbon legs.
That looks very characteristic of aluminum corrosion under a paint finish to me. You might want to scrape some of those bubbles off and see what’s underneath that.
r/thatssteel
carbon fork bubbles is a weird way to say rusted steel
Put a magnet on the crown to see if it’s steel.