Hairline crack in carbon frame

[Paradiddle]

I was cleaning my bike this morning and noticed what looks like a hairline crack on the joint of the seatpost and chainstay. It's about an inch in length and the width of a hair.

(I've tried to attach photos from Tapatalk but it has been behaving strange so let me know if you can't see them)

The bike is fairly new and bought from Sonder/Alpkit last September. So far it has only done less than 700km. I'm doing the London-Essex 100 ride at the end of the month and don't want this to get any worse.

Anyone have any idea what I should do?

As far as I can see my options are:
A. Get an opinion from a LBS
B. Get it repaired by a professional CF shop
C. Do nothing and hope it's superficial/cosmetic and doesn't get worse

Any suggestions or other ideas?

In any case I'll be contacting Alpkit about this. I'll need to check their warranty policy but I don't have much hope as their service has been disappointing so far.

[KM2]

Email so you have a date of the problem.
Surely this would merit a new frame?

[Dingdong]

I've seen a lot of damaged carbon professionally in my line of work, and that's not looking of the 'cosmetic' variety. If your frame is definitely under warranty you should get another no problems.

[Jdsk]

Your consumer rights are probably not limited to the warranty.

Ask the vendor for comments as soon as possible.

Keep a record of all communications.

Jonathan

[Paradiddle]

Thank you all for the input. Good to get a confirmation that this is not looking like just cosmetic damage.

I've just emailed Alpkit with the photos and quoted their Alpine Bond warranty which apparently covers their carbon frames for 5 years.
https://alpkit.com/policies/terms-of-service

Will keep this thread updated with any response from them.

The other worry is the 100 mile ride event I've got in 3 weeks. If repair or replacement takes a while then I won't be able to train for it or even do it.

[DevonDamo]

It seems like an odd location for a crack to appear - I'd have thought the big stresses would be on the underside of the frame, e.g. when your back wheel strikes a pothole and the chainstays are forced upwards, putting the bottom of the chainstays, close to the bottom bracket, under tension..

Of course, you'll want to exhaust all possibilities of getting the manufacturer/retailer to take responsibility for whatever it is but, if you can't get any joy that way, my number one priority would be to investigate whether it's the paint or the frame. Ideally, that would be by getting some effective paint stripper and clearing a centimetre-wide strip along the crack. If the carbon has failed, that should be visible in the carbon weave, and you may end up with a load of paint/stripper slurry in the crack, making an obvious line - similar to one of the methods used to locate cracks in metal. If it's not so obvious, you may have to use a magnifying glass and maybe find some way to apply downward pressure to the chainstays to try and get the crack to open up. (Creative use of ratchet luggage straps and/or bottle jacks may be needed here.)

[wirral_cyclist]

It seems like an odd location for a crack to appear - I'd have thought the big stresses would be on the underside of the frame, e.g. when your back wheel strikes a pothole and the chainstays are forced upwards, putting the bottom of the chainstays, close to the bottom bracket, under tension..

Maybe he hasn't looked underneath? OR, the top side gloss might be thick and show a crack, but unmarked below could be thin and stretches fine, I don't have enough CF experience, do you DD? Can you DD be really sure a top side mark is always benign, will you underwrite OP for medical or funeral bills?
Frame/bike is brand new, so the OP just needs to just skim it back to the retailer, for replacement, or for their reassurance, they'll surely be very happy to guarantee "it's fine, don't worry" and obviously insist on saying the same in writing, or not, so get any "it's only cosmetic in writing".

A chainstay failure will probably just hurt, if not actually as nasty as most(?) failed forks - though if the 40 ton artic is just inches away when you start losing skin it's probably a bit academic which bit of the bike actually failed...

To the OP, just train on that old heavy clunker and if this bike gets the all clear within the 3 weeks you'll fly round!

[Jamesh]

Obviously if a new frame then it's back to a manufacturer...

If an old frame id guess it's cosmetic, in that the paint has fractured rather than the CF.

I gave many such paint failures in my 10 yo Cannondale six which has done coast to coast and lejog.

Being that it's a gravel bike the layup is going to be quite heavy.

One good reason why a standard modulus is better than a high modulus frame in every day use...

[DevonDamo]

Maybe he hasn't looked underneath? OR, the top side gloss might be thick and show a crack, but unmarked below could be thin and stretches fine, I don't have enough CF experience, do you DD? Can you DD be really sure a top side mark is always benign, will you underwrite OP for medical or funeral bills?

I could understand your hysterical response, WC, if anyone had actually given a diagnosis or tried to convince the OP that that crack is definitely benign. However, nobody in this thread has given such a reply - we're all singing from the same hymn sheet, i.e. the OP's first port of call should be to get the retailer/manufacturer to deal with it.

I did comment that if I weren't able to get the retailer/manufacturer to deal with the problem, my next step would be to look at what's going on with the structure underneath the paintwork. I do have rather a lot of experience working with composites and I think this would be an eminently sensible approach, but if you, WC, have a better plan then I'm all ears.

[Dingdong]

It looks to me like a crack at the chainstay joint, it's weird because this is a really old (sic) fashioned bottom bracket design, I'd expect to see this on a frame from 2005-2010. It was popular on Italian frames of this era, from the likes of Bianchi and Dedaccia. Popular I'm thinking, until they failed in numbers. These U shaped carbon mouldings were never my favourite design and I've seen at least 3 frames with a fresh crack in roughly the same place.

Definitely a warranty job, if they are any way a decent manufacturer they'll have a replacement out to you asap. Though if it was me I'd be asking if there were a more recent design/model. Probably you could keep on riding it, as it may not get any worse. But if you have a serious thump on the road you might be walking home with a very expensive set of carbon fibre coat hangers!

[Paradiddle]

Thanks all for the replies. I did have a look underneath the frame last night and there wasn't any other crack visible.

I'm just waiting for a reply from Sonder and hoping for the best. Worryingly the carbon version of the Colibri has disappeared from their website a few months ago. I'm hoping it's not a quiet product recall or from them getting too many complains about it. The above comment about the old bottom bracket design does not give me confidence in the frame. I probably won't ride the bike until I know more about the damage.

I've also asked a local CF repair shop if they could give me an estimate for a repair. Could be a backup course of action.

[Paradiddle]

Update

Gave Sonder a ring today. The person on support looked through the photos and said it's unclear whether the crack is on the paint or in the frame. He suggested I get it checked out by a LBS before getting back to them with more information. If it is structural, he said they'll see what they can do in terms of repairs or other options.

He also mentioned that they no longer produce and sell the carbon Colibri due to sustainability reasons. He also had a look to see if they have any leftover frame left lying around and unfortunately it looks like they don't.

My next step will be to get the bike checked out by a LBS in person and hopefully they can provide a first-hand professional opinion.

[Nearholmer]

My gut feeling is that if this is anything other than cosmetic (and I’m not competent to even speculate on that), you have been sold an item that is “not fit for purpose” under the Consumer Rights Act, and should have redress accordingly. Since it is more than six months old, you may have to get an “expert opinion” to back any contention that it was not fit for purpose from the outset.

[Bonefishblues]

There are NDT (Non destructive testing) specialists if you do have to evidence an issue, but hopefully things will get sorted long before that.

[rareposter]

Update

Gave Sonder a ring today. The person on support looked through the photos and said it's unclear whether the crack is on the paint or in the frame. He suggested I get it checked out by a LBS before getting back to them with more information. If it is structural, he said they'll see what they can do in terms of repairs or other options.

He also mentioned that they no longer produce and sell the carbon Colibri due to sustainability reasons. He also had a look to see if they have any leftover frame left lying around and unfortunately it looks like they don't.

My next step will be to get the bike checked out by a LBS in person and hopefully they can provide a first-hand professional opinion.

I suspect that the only way to prove it one way or the other is an examination from a CF specialist, potentially involving X-rays or ultrasonic testing which could get expensive. If you can't tell if it's crack or paint defect, it's unlikely that a shop will commit to saying it's safe.

Really it should just be going straight back to the shop you bought it from or, if you bought it online either sending back to them or taking to an Alpkit store that's convenient for you. It's not really up to some random LBS to be declaring it safe or saying it's warranty, it's not technically anything to do with them. I know that if I had a Sonder bike and took it to my LBS, they'd obviously do basic repairs, upgrades etc but anything to do with frame integrity they'd say "take it to Alpkit".