when you've finished stripping a new find, start cleaning it, and discover a headlug/downtube braze joint is separating.

Yep, just bought this yesterday...

You see a great find at the Co-ops bike sale
[IMG]IMG_1389 by Ryan Surface, on Flickr[/IMG]

Only to see the fatal flaw
[IMG]IMG_1388 by Ryan Surface, on Flickr[/IMG]

Hmmm. That does look nasty, but looking closely at the photos I wonder why it is fatal. It looks to me like the paint crazed and allowed rust to start. The rust is significant, but the tube should be thick there. Is the fatality that this level of exposure indicates more serious internal rust, or that the rust you see is a structural problem in itself?

I think the discussion was that this indicates a front-end collision, and kinked tubes.
Although for the right price, I'd probably right the poop out of it anyway.

The double rust spots behind the head tube lugs is usually indicative of a front end crash and a compromised frame, too many great old bikes out there for me to want to deal with that. If I didn't have a zillion other projects I might have picked it up to salvage the Shimano 600 bits but I just wasn't feeling it.

Definitely a flaw, from a front end collision, but not necessarily fatal. These collisions can flex the frame enough to crack the paint and allow rust, but may not make the frame unrideable or unsafe. The pictures provided don't show how much, if any, permanent bend the frame took as a result of this collision.

Agreed. While the paint on the top of the tubes is the telltale sign, it's the condition on the underside of the tubes that's important. That is where the compression from the collision takes place and the tube starts to buckle.

After stripping the rattle can paint on a found Super Course frame I found cracks/braze separations on both rear stays at the seat tube. $40 at a local welding shop that also does motorcycle frames fixed it. I don't think they were structural, but at over 200 lbs, I felt better having them re-brazed. Pics of before, after re-braze and after final paint.

Try not to buy bikes in the dark, i mean sometimes you just have no choice cause you gotta get there before the other 40 ppl trying to get to it. Often times you miss stuff you'd easily see in the day when at night.

How did you know that is how I bought my Trek 610? I learned from the experience and told a seller that I don't like to buy in the dark. He cut his price in half. Pinarello for $150 was a good deal even though it look horrible. The parts on the frame alone are worth more.

Yup. Happens at least a couple times per year to me.

Last bad one for me was hidden under a bottle cage a couple months ago. Never fails, you'll see some, you'll miss some. It never fails to piss me off, though, and I've ranted about several here since I finally signed up after years of lurking.

A lot of sellers either don't think it's a big deal, others find clever ways to distract from or all-out hide damage.

Like the LeMond I bought at night during a driving rainstorm only to find the seized seatpost and rust bubbles the next day?
Not a killer flaw, the bike is still going strong, and is a joy to ride, just took a lot more work that I had planned.

I remember that thing sitting back there for months, though it was filed in alongside the million other ones in the back of the Bike Works warehouse, so I never got close enough to see the paint damage. They've had an old Fuso there for, I would say, a year or so. Don't know what they'll do with that. It's a 55cm give or take. There are a few gems in there, thankfully the Marinoni that [MENTION=340794]Dfrost[/MENTION] and I saw a few months back resurfaced and then dropped into my lap (I ride it often).

I thought I was on to something but I draw a line at front end collision damage. Someday I'll find a nice Centurion IM, A Marinoni is a nice score. Chapeau

I would be in the exact same boat, thinking hey, no one else is hip to this, and then seeing the paint...dang it. There are a few super tall Trek standard and touring models in great shape. The back of the warehouse is just a holding area and not a step-away-from-the-grave purgatory (thankfully). I'd love to help them out and refurbish those things so that they can sell them, but my/our current volunteering scope is not that wide yet...