Hi,
i have a 2 weeks old Carbon Racebike and have noticed the following marks on the frame right below the seat post at the back fork leading down to the cassette.
What is your take? Is this a crack going to run deeper over time? should I accept this despite the bike being actually brand new? No crash or abuse or anything.
Thank you
Sure looks like it. I would return it for sure to the shop or manufacturer.
Iâm guessing thatâs the seat stay? Hard to tell if itâs a crack, but the paint certainly shouldnât be coming off unless there was an impact or was scratched by something.
Tap it with a coin and then tap other areas with the same coin and see if they sound different (i.e the other seat stay). That looks like clear coat or paint issue but you can do simple sound test to help you make a more educated guess.
If it is that new and purchased from a LBS - most certainly take it to them also.
even if it were âjustâ a paint chip⌠would you accept this on a barely 2weeks old bike?
No⌠QA should have flagged that, not shipped it.
I wouldnât accept if it was brand new, never ridden.
It does look like something got dragged across the frame there. Maybe something got kicked up from the road? It does look superficial. If the frame just simply cracked, you probably wouldnât have the scratches across the paint. What are the bits of brown on the frame in that area? Dirt from the road?
Iâd do the tap test as posted above. If there are no dead spots then at least you know itâs superficial. If this were a local bike shop purchase, you could have them look at it and see what they say.
The tap test isnât infallible. In my experience it works pretty well across relatively even and unchanging stretches of tube but isnât ideal for sections where the curve and thickness changesâlike this spot.
This could just be paint flaking (what weâre seeing is literally paint), but it also has the kind of branching stochastic pattern youâd see on an actual crack. Either way, some trauma had to cause it, and on a brand new bike if that wasnât you, Iâd most definitely be taking it back to the shop. To me it looks alarmingly like the kind of crack youâd expect if that spot had been directly hit, hard.
The frame is unsafe to ride, return it immediately and insist on getting a new one or a full refund.
For a crack that is this obvious, is a tap test even necessary? Personally, Iâd just refuse to ride it.
Thank you all. I have taken it to the shop and they are looking at it.
There was no direct hit, no abuse or anything.
There was a little brighter spot on the same place already when I got the bike and I asked the dealer about it. He looked at it and mentioned it would be the usual change of color on carbon you find regularly all over the frame. True, there are these different shades on this mate black carbon frame.
But the original brighter spot turned into this and that makes me worry.
Fully agree.
If there was a difference in the surface appearance then this and you already pointed it out to the shop I would think somewhere along the line someone tried to cover up either a scratch, chip, or other imperfection that is now visible. It was likely there before you purchased it, just covered up.
I am quite convinced that the damage will further grow under stress
This sounds a bit dramatic. The smallest imperfection blown up in a digital photo often looks like some giant disaster.
Most people have nicks and scratches much worse looking on their 5 or 10 year carbon bikes and nobody is telling them that their bikes are unsafe to ride.
This could be a defective frame. Iâm not denying it. Even if it was, I doubt a failure there would result in anything catastrophic. If this were my out of warranty, used frame, Iâd do the tap test and keep my eye on the spot.
In this particular case, Iâm glad the dealer is involved.
so, you would ask for an exchange if it were your brand new bike?
Letâs assume that it is an entirely cosmetic issue. On a two-week old frame I would find that unacceptable and return it. The outcome is the same.
The problem with carbon is that you need to do an ultrasound if you are in doubt. Is it worth it if it isnât your fault?
If it wasnât like that out of the box (it wasnât), then nobody is going to take back a frame that got scratched in some way.
Honestly, Iâve had frames scratched while riding out on the road and I never even noticed it until after the fact. Something gets picked up by the tire, swings around and smacks the seat stay right in that exact spot.
The spot was different from the very beginning and the vendor acknowledged this (I hope it stays that way).
I do not know, what kind of impact could have been there and cant imagine, what would have been picked up from the road to hit this very spot. I rather think it is a damage which was there from the very beginning and got bigger during ride, being exposed to my weight (90kg) and to stress while riding.
so what now?
So that looks like a âvoidâ, or porosity in the carbon processing. (The lightness was caused by no backup carbon or resin) Not at all a great sign for their manufacturing process, or their especially their quality control process either. True, most frame manufacturers will completely over process some spots in the frame like the BB shell area (I saw a Specialized frame that was replaced and they didnât want the frame back, so the shop cut it into pieces to show the construction. The BB area was seriously over engineered) but that looks like the junction from the seat stay and top of the seat tube, so there is a lot of stress in that area. The vibrations would come from the wheel hub, through the chain and seat stays, so either that spot would fracture right away, or over time it would. Either way, having a seat stay jutting out under pressure while riding rough-ish terrain doesnât sound comfortable. It is also possible that it would never fail, but the one issue with carbon fiber is that it doesnât bend like aluminum, or steel. Yet it can show indications of imminent failure, but it can also show no indications on a visible level and yet suddenly completely fail.
I, personally, would never ride a bike of mine that showed any possible damage (that I didnât know about before hand)
(I have a really old Trek Madone that has some damage on a seat stay. The core is visible through a small area where the overcoat is missing, and I can see they used solid carbon fiber rods for the core, so Iâm comfortable thinking that they were over designed enough that the frame is safe for normal riding, but if I see the injury getting worse, itâs off to the wall in my garage for that bike, on display so I can see it and remember the great rides we had.
Any damage on a carbon fork, and itâs done for.
