3alarmer 

...
...that's about it. I know nothing about them. This one seems well put together for its age.
It has a strange seat tube problem I've not encountered previously, but I hope to get that sorted.

Also, I presume the routing for the front derailleur cable runs under the BB shell and up through the angle purposely set nto the stay bridge. I can figure out no other solution, unless the frame is missing something, and I can't see where anything has broken or fallen off. Thanks for any information or references.

rhm

That's pretty cool!

I don't see any evidence there was ever a front derailleur.

KenNC

A very interesting frame, hope we hear and see more about it! I have a 1970 Witcomb of London that had a small crack in the seat tube similar to yours, apparently from having too large a seatpost forced in. Hasn't been a problem for me now that I have a proper post in it--27.0 and not 27.2 . I did have a tiny hole drilled at the end of the crack by a local frame guy, but not sure that was even necessary. Given the seat stay placement on yours would you be able to reach the end of the crack with a drill? In any case I hope you get your sorted out, or get comfortable with it, as that looks like a very interesting and high quality frame.

3alarmer 

...yes, the small relief hole, drilled at the bottom of each crack. along with a well fitted new seat post, is my backup plan. Good to hear that yours has not been a problem. I am waiting to hear back from the local frame builder here on my e-mail inquiry re solutions. When I look at it, it seems to me that the stresses from the post itself ought to exert mostly on the clamp at the top, which is fine, and the lower portion of the post insertion, which I intend to make relatively long. the other stresses would appear to be from the seat stays pushing up at their attachment, which is also solid, with no evidence of failure.

The tubing has very thin walls, and the frame is light, for something made from steel in the 70's. I haven't tried to fit the new post yet, but perhaps this was another case of fit error. Thank you.

SJX426 

@3alarmer - I don't see any evidence of FD either. Only one marking from a cable on the BB shell, or is there a light marking for a FD? Only one guide too.

The paint looks thick. Is it a repaint in your opinion? If so, do you plan on stripping? The condition of the paint might justify a strip. Then you can assess the cracks you presented. That might explain the lack of a cable guide for the FD on the BB shell.

Interesting CS bridge with that curve feature.

3alarmer 

...
...the current plan is to wait for a response from the frame builder, Steve Rex. If he has some kind of genius fix that involves a reinforcement at the botom of the crack area, I'll pay him to do that. If not, drill a couple of relief holes, carefully fit a new seat post, then build it to rideable condition. At that point, I'll try to fit a front derailleur and run a cable under the BB, first trying out the run as under there and through the formed groove in the stay brace.

If that seems iffy, I'll probably install one of those plastic thingies on the underside of the BB shell and see how that works out.

I do think I'll probably paint tit, but not until I'm convinced I like riding it enough to warrant the effort. It looks like an easy white to match, so I can pretty much touch up the bad spots in the meantime. I guess it's a product off one of the guys who got out of frame making, and did not make and sell enough of them to leave much in the way of a history. It does seem to me to be very well constructed. Like a labor of love.

Paint looks original to me.

repechage

Those cracks do not look good.
Probably is repairable, but at what cost?
I vote retirement.

3alarmer 

...interesting. Given a well fitted (snug slip fit) post that extends far down into the seat tube, what do you think will be the manner of eventual failure ?

I get that the stays do push up and a little forward, but if this were a high stress area, that would argue about ever slitting a seat tube/stay lug as a construction method in the first place. I think. Maybe. I could be 100% wrong on this. My best guess is that the initial cause for this was someone running a seat post in too small a diameter. Which is just my best guess, because it came with only a Tange bottom bracket and an Avocet headset.

No history, no provenance. Anyway, if I get an answer from Steve Rex, I'll post it in the thread. Like I said, I've never personally seen this mode of failure before.

repechage

failure has started. It won't heal itself. let's say you can get ahead of it with a stop crack drill on both sides, the stays are still less supported than they could be.
For a time is no object repair, I would detach both stays at the same time. fit in a reinforcement half sleeve, the stays will need to be re-mitered, and there is where the big energy will be spent most probably, always possible detaching the stays will also present hidden stress that will show up in the form of a bend or twist in the stays. The stays might be pliable to get in and dress with a spindle sander sleeve, unknown. then it all has to be brazed up again, keeping the alignment in check. Note too the dropouts were heavily filed back, that could be the next domino of failure.

The balance of the frame up front is not impressive, but it could just be the lousy paint, one headlug shows a curious crack in the paint around the outer edge of the lug shoreline.
if a repair was contemplated, get all the paint off by chemical means and assess for overheating of the tubes and cracks that are lurking elsewhere. Then take it to the builder.

3alarmer 

...thank you.

rhm

The paint may be too thick, but the lug lining is fabulous. I wouldn't want to try to redo that. Where it's chipped, the metal is shiny. Is it chromed?

3alarmer 

.
...yes, the paint is very thick. And yes, as far as I can tell, the whole frame is chromed.

repechage

Mr Rex upon seeing the whole frame bare, may well advise punt.
Or get the chrome removed. Might be possible to submerse most of the frame and retain the chrome stays upon de-plating. You will need a co-operative plater.

3alarmer 

...I'm prepared for all possible outcomes. It is not something I had planned on investing heavily in. Worst case is I will end up stop drilling the cracks, fitting in a proper seat post, not go to all the work of a proper repaint, put it together with parts on hand, and see what happens. I guess I could go with a stainless hose clamp beneath the stays and below the cracks as a tacky accessory, but I am loathe to do that.

I don't much care about saving the frame chrome, and have been known to repaint chrome forks to match frame color.

repechage

While seat stays are lightly loaded in general, the crack is at a placement where a tear will just propagate.

3alarmer 

...yes, thank you. I think I understand that issue. I'm still puzzled why slicing the seat tube in the rear seems to be such a popular construction method, and why you see this sort of failure so rarely on bikes that get ridden pretty hard and put away wet. Upon inspection at initial receipt, the ears of the top lug were definitely drawn inward, in the manner you sometimes see with an undersized post fitted to the frame.

My speculation (and it is only that), is that in this case, the thin frame tubing walls of a higher end frame tubing set, coupled with the fastback stay cluster design, and too small a seat post, gave just enough flex in the area of the bottom of the slotted tube to initiate this failure. It also looks like whoever built this frame did not do much relief rounding at the lower end of the slot. In retrospect, this seems unfortunate.

My hope is that with some relief drilling and a well fitted post for support, it might be either arrested, or at least become one of those failure modes that can be ridden for years without much danger. Certainly the clamping action of the seat lug on a properly fitted post is what makes this design possible in the first place. Ah any rate, it should be obvious if this was a bad surmise on my part well before any sort of catastrophic failure occurs, wouldn't you think ? Or am I mistaken ?

We do have the earlier post in the thread by someone with a similar tear, who has done a similar thing with success. But I'm guessing from his description of his frame he has a more traditional seat stay attachment.

I always wondered about those wrap around stay attachment designs, as to purpose. I guess this might be one reason for doing that.