Charles Wahl

Awhile back I noticed this as a sort of crack in the paint, which then began exuding dark material (steel rubbing steel). That has abated somewhat now. I don't think that this is just rust under paint, because I keep the bike very sanitary and waxed.

I'd be interested in comments from those of you who've seen head lugs fail: what's the failure mode -- face plant?



Frame is a 57 cm 531C tubeset Raleigh ridden on and off for 25 years, and I weigh 180#. I don't punish it.

unworthy1

this seems like a good question for the framebuilder's forum...but if I was to bet on it, I'd bet it won't fail catastrophically, and seems like the "dark matter" has to be rust.

JohnDThompson 

Steel frame failures are seldom catastrophic. This looks like the crack started in a void area in the lug window and is in the process of spreading through the lug. You could drill a stop hole at the end of the crack to prevent it from spreading, then re-braze the void are to fill it properly.

nlerner

Do I also see a hairline crack on the head tube, just in front of the lug or is that an optical illusion?

Neal

Charles Wahl

No, Neal, I've scrubbed off the whole area with a soft toothbrush, and no marks or cracks visible except the one I've pointed out. What's curious is that the rusty sort of stain within the top margin of the window doesn't disappear. I wonder if that zone is starved of braze, leading to the crack in the web.

Full disclosure: about 8 years ago I did hit a low concrete wall at low speed, just fast enough to take a header over it, taking the bike with me. I've never seen any evidence of frame damage (crumpling, rippled paint) from that, though.

JohnDThompson 

That's my suspicion, and what I referred to above as the "void area in the lug window."

John E

I have broken four steel frames (one bottom bracket/seat tube lug, one chainstay, and two downtubes just behind the head tube lug), and I can confirm that none of the failures was life-threatening in any way.

EjustE

You are fine.

That part of the lug is primarily decorative. That's why the cutouts are there. About 95% of the pressure of the lug is on the 10% front part. Lots of lugs did not go as far as where your break is and they were fine structurally.

Don't sweat it

Charles Wahl

Ah, I thought you just meant the window as a void.
That's reassuring.
I appreciate the advice.

Now my trouble is, that I'll probably retire the frame soon (have others that fit better), and I had thought to sell it. Maybe I'll just end up giving it away, with disclosure.

old's'cool

The thing about cracks is, once they start they will continue to grow until they reach a free edge of the material., unless something is done to stop the crack's growth. So bear that in mind. My concern in this particular case is not only the aesthetic aspect of the lug eventually having a crack all the way across, but that it is possible for the crack to propogate through the braze and into the down tube. Not saying it will happen, but I don't rule it out.

If I were to set out to increase the survivability of the frame with the least intrusive yet effective repair, I would grind out the crack completely using a small dremel ball end tool, making sure I penetrated to the braze underneath the lug, and beyond the visible tip of the crack. I would then fill the ground out area with some kind of putty, sand and smooth to the original contour, then touch up with matching paint. Use of the bike might cause cracks between the putty and parent metal that may need touching up from time to time.

repechage

It is interesting that it started on the lug, which is the more ductile than the tubing, these lugs were probably the stamped type. It is not I would think going to fail suddenly. I do think it will continue to grow, if I had access to an industrial x-ray, I would love to see what the actual internal joint is like. I have seen enough frames dismembered to know all that is shown from the outside is not what is really going on.

The stress of the impact is expressing itself here, now why is it showing on the lug, other than the sharp corner of the lug window?

Note to builders, radii everywhere...

JohnDThompson 

A better fix would be to drill a stop hole at the end of the crack and then fill the whole works with brass.

unterhausen

I wonder if there is any filler between the window and the head tube at all along that side of the top of the lug. I'm guessing no. Actually, that's one of the more stressed areas of the lug that doesn't seem to have enough filler. I don't even know if you can fix it at all. I don't think there is a magic method of cleaning that area out chemically, I'd like to know if you could do that.

GamblerGORD53

+1 Neal I also see a crack in the head tube and a dimple / bend in the DT se from the rust spot.
Likely a wee crack under there in the tube.
You are lucky that it hasn't gotten worse after those 8 years.
Ask the frame builders if it is possible or necessary to re-braze it.

redtires

Not to make light of the OP's situation, but that last line.....only a pun a framebuilder could love. (btw...JDThompson's suggestion is probably the best, especially if you would like to keep on riding that frame. A good local builder should be able to handle it for you...you'll have to re-do the paint though.)

JohnDThompson 

I'd try blasting the area first, followed by an oxalic acid soak, then plenty of flux while brazing. Flux actually does a heck of a job of removing corrosion, but it has to be fully heated to work.

old's'cool

Stop drilling and filling with braze is certainly a step in the right direction but have no illusions that the fatigue strength in that very localized area is anything but a fraction of what it was as designed.
If you drill a hole through to the down tube you have now introduced a stress riser into a very highly stressed member that did not have a stress riser (other than the crack in an adjacent member) before.

Charles Wahl

There's no crack in the head tube, nor a dimple in the down tube. Maybe one day I'll strip it, have that fixed if possible, and powdercoat the whole frame. Until then, I think I'll give drilling and the like a miss. Thanks, all.