2000 C40 Repair Advice

[cd_davis]

Hi all - I own a 2000 Colnago C40 in 8.5-9.0 out of 10 condition. Except for the second time, corrosion has developed on the rear dropouts; this time on the inside of the right rear dropout at the chain stay interface. Two pics are attached, along with two pics of the undamaged left side. Colnagos of this vintage have been known to have this problem.
At the corrosion site, the minimum thickness is ~12mm. I have options to consider for this bike:
1. Clean up and paint the corroded area, but with a question of strength and safety; is it strong enough/safe to ride?
2. Get a carbon repair service to overlap carbon at the stay and drop junction, paint, and clean coat so it looks like the left side. One repair estimate is $375 plus getting shipping the frame to/back. Figure $75 for that. The frame might be worth $600-750.
3. Part it out, sell the Colnago Star 1 inch fork, seatpost, donate the Mavic wheels to a junior club, sell the great condition 7800 gruppo.
4. Donate the bike as is to a junior club in the DR that CCB supports.

Although not my primary ride for years, but one favorite, it may be time to let it go. I'd appreciate advice on the pros and cons of the options, what am I missing?
Thanks
Chris

[prototoast]

So the problem here is that the corrosion is where the aluminum dropouts are bonded to the carbon. This can cause the bond to fail, and the dropout can separate from the chainstay. Personally, I wouldn't ride this as-is. I'd also be hesitant to do the cheapest carbon repair solution (overwrap with carbon to secure the joint) because that still leaves underlying corrosion. I'd opt to replace the whole dropout, but that would likely cost more than the frame is worth.

[m_sasso]

Long discussion here, too long for me to read it all, so don't know if a solution was reached besides retirement. https://www.roadbikereview.com/threa....245227/page-3

[cd_davis]

Hi M_Sasso - wow, long read back and forth, lots of impolite BS. The thread points to retirement of the frame.

[m_sasso]

Originally Posted by cd_davis

Hi M_Sasso - wow, long read back and forth, lots of impolite BS. The thread points to retirement of the frame.

I would go to a respected Carbon specialist ask for an estimate on a ultrasound determination on condition of the joint and the possibility on cleaning the joint surfaces up if required and rebonding the dropout. Viable cost is your decision. I would not be to concerned on the current drop out thickness at the axel, lots of material.

Your second picture although dark appears as though the chain has been dragging on the drop out to chain stay socket and abraded away a good portion of the drop out to chain stay socket? This looks like a bigger issue to me. Is your axel properly spaced?

[Nomadmax]

Originally Posted by cd_davis

Hi M_Sasso - wow, long read back and forth, lots of impolite BS. The thread points to retirement of the frame.

Yow, I'll never go there and ask a question

[C40_guy]

My heart breaks for you Chris...I know you love that C40. I loved mine too...and I love my C50 even more.

I'd be tempted to say "screw it, whatever it costs, it's staying in the stable."

But...as we talked about offline, your stable is pretty full. And you said you could donate it to a developmental team.

Many years ago I donated my first road bike to a Bikes across Borders group or something similar, and I still get a kick picturing some young person riding a vintage racing bike with Nuovo Record components to school in the bush or whatever.

It felt good moving it along.

Just saying,

...and more of my fleet seems to be moving towards the forever Ti bike. Litespeeds and Lynskys and Merlins and Moots and cockroaches will be here after the world ends!

[weiwentg]

My main bike is a custom frame from the mid 2000s that takes 25s, and can sort of just barely take 28s. If it had some sort of equivalent damage, I'd repair it for sure. Too much sentimental value. You don't need to make this decision purely based on logic.

However, I basically don't have any other active bikes right now. So your calculus will differ.

[dgauthier]

If you yourself wouldn't ride it, I would think donating is out of the question unless you can be sure it wouldn't be ridden in that condition. Unless you repair it, part it out and retire it.

Edit: On this forum we talk a lot about what one's teeth/head/life are worth compared to various bits of equipment. If you can't be 100% comfortable a repair will make the bike as good as new, it's time to move on.

[Spoker]

With 3 d printing progressing a replacement dropout will get affordable in the future maybe?

[cd_davis]

There is no chain drag and the axle is properly spaced. I can understand your thinking, but that’s just the way the corrosion eroded. Thanks for all the comments. And if it is unsafe, I would never donate especially to a junior club.

[cash05458]

Entirely up to you...of course...but those C40's are such nice frames so I would say invest some to fix it properly and enjoy it. Yeah, it may only be worth "so much"...but I don't think great frames really go by that measure...but I say this knowing what I would do and pay if my beloved C50 came down with a bad problem that involved some money to save.

[C40_guy]

Originally Posted by cash05458

I say this knowing what I would do and pay if my beloved C50 came down with a bad problem that involved some money to save.

Same here. I "graduated" from a lovely C40 with a wonderful classic paint job (can't remember the name of the colourway) to a nude carbon C50. I regularly tap every tube just to make sure all is good...if it needed repair I would not hesitate...

I have a feeling Chris might go the same route.

[cash05458]

"I would go to a respected Carbon specialist ask for an estimate on a ultrasound determination on condition of the joint"

I think this is solid advice...I will say tho I think folks overreact about safety on frames and parts at times...not saying that here so check it out maybe...it is very rare that frames just explode and you go down hard...I have had a few frames break over the decades and I would be riding and then notice a difference...and be ok...of course some here will spin it to imagining you are cooking down a mountain and that stay goes and you are catapulted over a rail and need spoon feeding for the rest of your days...which is always possible in bike riding of course...maybe just ride it and see how it feels and watch and use your common sense...

[Spaghetti Legs]

I feel your pain. I have a worn and partially stripped BB shell on my ‘96 C40 which I fortunately found a solution for. At the time I was sorting it out, I learned Colnago isn’t interested in performing repair work on these older frames.

In your situation I would want to learn more about the corrosion process. Does it just occur on the surface? If that’s the case, then it could be treated similarly to a rust repair, take it down to healthy metal and then build it back up.

That’s one area where I would think a sudden failure is possible and a sudden failure could cause some significant injury.