blakcloud

Yes. I fully understand that you can't tell much from this particular photo but I am asking a more generalized question. Is this common with through axles and carbon bikes?



Her is my correspondence with the seller

Me: The red paint is showing through where it shouldn't. Right at the through axle. Can you tell me what is happening?
Him: The red paint is underneath the black, and it's common for paint to flake on carbon bikes where the thru-axle threads into the frame. Nothing structural there, and it's been consistent on all of my carbon TA bikes.
Me: I am going to pass because I am not confident that the flaking paint is just flaking paint.
Him: I work full time at a Trek shop and am the service advisor/warranty contact. I assure you it is flaking paint and nothing else.

He doesn't own the bike but is selling for a friend, so the ad says. My guess is the through axle was tighten too much and at bare minimum cracked the paint but maybe more. TA don't know the same kind of tightness as a quick release.

So, would you drive the 90 minutes to look at this bike or would you just pass? We are talking about a $5000 Cdn selling price here.

So do the experts and non-experts here think/know that paint flakes at the through axle?

CliffordK

The first thing I'd do is try to track down a good description of the rear-end construction on that frame.

I see two bolts below the paint spot which I presume go to the gloss black rear derailleur hanger. Can you tell if that is an OEM hanger?

Then, there is probably an aluminum insert that the thru-axle threads into. Is that insert removable?

Where does the carbon end and the aluminum begin?

My guess is that aluminum thru-axle insert has moved slightly. I don't know if that is normal for that frame.

You could try the manufacturer customer service or technical support.

As you probably know, once you purchase a used bike, you likely give up all warranty rights.

mrt2you

i would ask for a close up pics of the area in question possibly from different angles. if you can't get those pics i would move on to another bike.

MattTheHat 

I’ve owned three carbon thru-axle bikes. None have paint chipping at the drop out like that. I’d pass.

HillRider

What is so special about this bike that makes it worth $5000 Cdn? Unless this is a real exotic (and the Ultegra DI2 tells me it's not) for that kind of money you could get a quite high-line brand new bike complete with warranty.

Marcus_Ti

What brand of bike? That is sloppy masking and painting

hokiefyd 

It may be the picture, but it almost looks like the black is some sort of plasticized coating on top of the red paint. It almost looks like plastic has cracked and come off.

If it's not plastic, and is just black paint, why would there be red paint under black paint? Would the red paint be some sort of primer?

CliffordK

There is red on the chainstay. If the bike was painted in layers, one might get red under black.

But, it is an odd mix of gloss red/black, and flat black.

Perhaps it is a plastic chainguard.

Hopefully it wasn't rattle-can spray painted.

In that case, one might need careful inspection in person, or by a 3rd party mechanic of the area. Perhaps cut a thru-axle stub to thread in, and see if there is abnormal flex in that threaded insert (I can't say what would be normal).

blakcloud

Thanks for everyone's opinion. I should have mentioned the brand of bike because it might help. It is a Trek Domane SL7 (2017) with carbon rims and Di2. This bike in Canada is $10,000 so the price is alright if the flaking paint wasn't there. I would own if it didn't have that.

AnkleWork

The used bike is over-priced until and unless proven otherwise.

Driving 90 min to evaluate the bike makes the Trek guy's expertise irrelevant -- I'd have to get a discount for that.

Driving 90 min to evaluate the bike weakens your negotiating position and strengthens the seller's -- I'd have to get a big discount for that (in writing). Good luck with that.