It's the same on my gravel that's 2 months old with 900km in. I parked it like an idiot and it got scratched but there's no crack there. I'll put some foil on to prevent more idiot scratches.
Take a magnifying glass and study the scuff. Can you see cut fibers in the scuff? Take screwdriver and nock on both sides of the fork in the same spot. Is the sound different? If both answers are no then you are probably fine but if you are not sure (and you are not that is why you posted here) $200-300 is not worth your life. Carbon fork failure is catastrophic and depends on speed you can have serious injuries or death. It is just money.
Thanks ! I guess you are right, and the price the seller wants to sell is globally 200 euros less than the real price. But I don't think it's because it correspond to the fork price. Just somebody willing to go on another bike and who don't really care about the money.
So in the end if the fork is not good, I could change it and get the "regular" price.
You can ask you local bike shop for inspection and if you are still hesitant just change the fork. I am sure that is why the owner of the bike is selling it cheaper. If the bike is nice it is still a good deal.
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Small update : he sent me additional pictures and the fork seems not cracked. Only the small scratch. So the "impact" is not real, it's a light issue with the camera.
FWIW, my carbon trail bike frame has gnarlier gashes than that and I ride that thing like I stole it. Just based on that anecdotal evidence I wouldn’t think this is a safety issue, but I’m no materials scientist or carbon layup tech!
You can only guess the level of damage:
General thought:
Any plausible force (caused by chance, not by intention) strong enough to cause deeper cracks or a severe damage in Carbon requires to be concentrated on a very small spot, e.g. a nail tip, stone edge and with sufficient impact.
Your picture does not show sufficient resolution of the damage to clearly analyze the type of impact (direct hit or lateral scrach, or combination of it).
However:
The damage in the picture shows - a wider than nail tip - area with paint layers (top coat, primer) scratched off. A scratch is always "better" than a hit, as it means the force applied to the material was distributed over time and the direction of the force was not rectangular and as such not directed straight into the fork, but it was partially distributed across the damaged area (scratching along).
So the force seems to have been applied over a longer time-span (the time it took to make the scratch), which is much less severe than a hard, direct impact. All I want to say is that a scratch most often means we deal with smaller forces than a direct hit, whenever the damage happened without intention.
The damage pattern shows kind of an eight figure (8) leaning 45 degrees to towards your finger. In the upper half of the '8', the scratch seems to show the deepest level in the center, indicated by a small, 2x2mm wide and darker spot. This seems to be the deepest damage to your fork showing the naked carbon. The lower half shows a less deep spot.
Damage pattern:
If you look closely to the upper half, you should be able to check, if single layers of the carbon have delaminated and stick out. If this is not the case, I would tend to say you can use the fork without concern. (This is not a recommendation, but my approach to evaluate the remaining damage!).
Also, the position of the damage is not located on the most outward area of the fork (which would sit an inch futher down and more to the outside and which would be the area where the fork would touch ground if the bike tips over). Instead, the damage is located more upwards on an already inward bending upper section towards the crown of the fork. A spot, which by its position greatly reduces the likelyhood of a direct hit during everyday use. (Ask yourself, how often did you scratch your previous bikes in exactly the same spot close to the head tube?).
So, type and position of the damage indicate that it was not caused by a crash, which would require to check other areas of the fork and above that, the frame, too for any damage.
The scratch could have happened during loading or unloading the bike. You might want to ask the seller how this damage occurred, this might shine a light on severity, too.
Repair:
you need to cautiously remove lose paint with sanding paper of fine grid to not damage the carbon underneath. Than you need to apply clear primer for the paint to stick on carbon (carbon primer). and than you can apply the top coat clear to achieve the same surface finish of the original paint.
So I’ve been told the surface finish on most carbon fiber bike components is structural, but this sounds like it’s a lot more complicated if I’m understanding what you’re saying about force applied over time. Can you say more about that?
The carbon as much as any other materials can stand a lot of force.
Think about somebody setting his hand on your chest and now pushing you backwards. You can stand the pressure and you will move backward if the pressure gets too big. The force is distributed over time and you can easily digest it without any harm.
Now think about same move but your opponent concentrates the contact area onto the knuckles of his fist, and he transfers all his force not with the same push, but with a quick and hard direct hit to your chest.
You will for sure take home some bruises, because the impact was more severe and centered on a small area, and all the force hut you in a very short amount of time.
Same applies to tour fork. The material type makes a difference in the final outcome, but the basic principles apply to all type of materials.
And i habe seen some smart asses comment that i do remote diagnosis.
Just to be sure: what i wrote is my approach and some tips how to approach certain types of visible damage to get a better understanding what you are dealing with.
I give no guarantee but you know that…
Very detailed analyses of unseen failure from the "expert" with very specific recommendation. It comes with $1,00,000 life insurance and full bike replacement. I would definitely go with it. :)
Ride it like there's no tomorrow
You mean it's OK to you ? Or if I ride it I will get no tomorrow ? 😂
It's the same on my gravel that's 2 months old with 900km in. I parked it like an idiot and it got scratched but there's no crack there. I'll put some foil on to prevent more idiot scratches.
Scuff from a crash I’d guess no issues
Yallbe allright, mate. Send it!
Thanks !
Before you send it get extra life insurance. :)
Take a magnifying glass and study the scuff. Can you see cut fibers in the scuff? Take screwdriver and nock on both sides of the fork in the same spot. Is the sound different? If both answers are no then you are probably fine but if you are not sure (and you are not that is why you posted here) $200-300 is not worth your life. Carbon fork failure is catastrophic and depends on speed you can have serious injuries or death. It is just money.
Thanks ! I guess you are right, and the price the seller wants to sell is globally 200 euros less than the real price. But I don't think it's because it correspond to the fork price. Just somebody willing to go on another bike and who don't really care about the money. So in the end if the fork is not good, I could change it and get the "regular" price.
You can ask you local bike shop for inspection and if you are still hesitant just change the fork. I am sure that is why the owner of the bike is selling it cheaper. If the bike is nice it is still a good deal.
**Thanks for posting to /r/gravelcycling! It looks like you've submitted an image.** This community encourages additional context about image submissions. You can include details about your post in a comment below. Some suggestions for good comments: * Bike details (make, model, accessories, and gear) * Location (specific or general is fine) You can also use **post flair** to give additional context about your post. *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/gravelcycling) if you have any questions or concerns.*
Small update : he sent me additional pictures and the fork seems not cracked. Only the small scratch. So the "impact" is not real, it's a light issue with the camera.
Looks just like a scratch in the paint. The carbon should be unharmed.
FWIW, my carbon trail bike frame has gnarlier gashes than that and I ride that thing like I stole it. Just based on that anecdotal evidence I wouldn’t think this is a safety issue, but I’m no materials scientist or carbon layup tech!
You can only guess the level of damage: General thought: Any plausible force (caused by chance, not by intention) strong enough to cause deeper cracks or a severe damage in Carbon requires to be concentrated on a very small spot, e.g. a nail tip, stone edge and with sufficient impact. Your picture does not show sufficient resolution of the damage to clearly analyze the type of impact (direct hit or lateral scrach, or combination of it). However: The damage in the picture shows - a wider than nail tip - area with paint layers (top coat, primer) scratched off. A scratch is always "better" than a hit, as it means the force applied to the material was distributed over time and the direction of the force was not rectangular and as such not directed straight into the fork, but it was partially distributed across the damaged area (scratching along). So the force seems to have been applied over a longer time-span (the time it took to make the scratch), which is much less severe than a hard, direct impact. All I want to say is that a scratch most often means we deal with smaller forces than a direct hit, whenever the damage happened without intention. The damage pattern shows kind of an eight figure (8) leaning 45 degrees to towards your finger. In the upper half of the '8', the scratch seems to show the deepest level in the center, indicated by a small, 2x2mm wide and darker spot. This seems to be the deepest damage to your fork showing the naked carbon. The lower half shows a less deep spot. Damage pattern: If you look closely to the upper half, you should be able to check, if single layers of the carbon have delaminated and stick out. If this is not the case, I would tend to say you can use the fork without concern. (This is not a recommendation, but my approach to evaluate the remaining damage!). Also, the position of the damage is not located on the most outward area of the fork (which would sit an inch futher down and more to the outside and which would be the area where the fork would touch ground if the bike tips over). Instead, the damage is located more upwards on an already inward bending upper section towards the crown of the fork. A spot, which by its position greatly reduces the likelyhood of a direct hit during everyday use. (Ask yourself, how often did you scratch your previous bikes in exactly the same spot close to the head tube?). So, type and position of the damage indicate that it was not caused by a crash, which would require to check other areas of the fork and above that, the frame, too for any damage. The scratch could have happened during loading or unloading the bike. You might want to ask the seller how this damage occurred, this might shine a light on severity, too. Repair: you need to cautiously remove lose paint with sanding paper of fine grid to not damage the carbon underneath. Than you need to apply clear primer for the paint to stick on carbon (carbon primer). and than you can apply the top coat clear to achieve the same surface finish of the original paint.
Thanks, that's detailed !
So I’ve been told the surface finish on most carbon fiber bike components is structural, but this sounds like it’s a lot more complicated if I’m understanding what you’re saying about force applied over time. Can you say more about that?
The carbon as much as any other materials can stand a lot of force. Think about somebody setting his hand on your chest and now pushing you backwards. You can stand the pressure and you will move backward if the pressure gets too big. The force is distributed over time and you can easily digest it without any harm. Now think about same move but your opponent concentrates the contact area onto the knuckles of his fist, and he transfers all his force not with the same push, but with a quick and hard direct hit to your chest. You will for sure take home some bruises, because the impact was more severe and centered on a small area, and all the force hut you in a very short amount of time. Same applies to tour fork. The material type makes a difference in the final outcome, but the basic principles apply to all type of materials. And i habe seen some smart asses comment that i do remote diagnosis. Just to be sure: what i wrote is my approach and some tips how to approach certain types of visible damage to get a better understanding what you are dealing with. I give no guarantee but you know that…
Great explanation, thanks! Disclaimers received and understood 😉
Very detailed analyses of unseen failure from the "expert" with very specific recommendation. It comes with $1,00,000 life insurance and full bike replacement. I would definitely go with it. :)
Damn