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Sleeve to repair broken top tube, replace tube, toss in the trash?

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Sleeve to repair broken top tube, replace tube, toss in the trash?

Old 09-23-16, 09:59 AM
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Sleeve to repair broken top tube, replace tube, toss in the trash?

I picked up a broken Somec (Columbus tubing, probably SL) on Chicago CL yesterday for its parts. This photo from the seller explains why I didn't buy it for the frame:



I felt under the down tube when I picked it up, but felt no ripples. You can see a pretty big distortion in the top tube behind the break.

I got to thinking, could the top tube be cut off a half inch or so behind the break and an external sleeve brazed on to cover the area of the break? Clearly, it wouldn't look perfect (the sleeve could be sculpted to have shorelines and windows similar to the original lugs), but it might still turn out to be a functional frame. Is there enough metal left between the break and the head tube lug to make a strong joint?

Clearly, I haven't thought this through to much yet. Some things which did occur to me, however:
  • The frame might well be damaged in other areas I've yet to discover
  • It might be better to just replace the entire top tube
  • If it was originally silver brazed, heating the metal to braze on a sleeve might well compromise the brazing of the head tube lug

Right now I'm just in the idle speculation stage. Assuming no other damage to the frame or fork though, I think this frame might well be repairable.
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Old 09-23-16, 08:37 PM
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Yes, a sleeve could be made that could work, and yes it would look really odd. Disturbing the original brazing wouldn't be a concern.
But why did it break like that in the first place? Was there damage that caused a crack? A cable guide right at the butt transition and many thousands of miles of stress?
I'd be really suprised if there wasn't some other frame damage anyway.
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Old 09-23-16, 09:29 PM
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Thanks. I had some time this evening while stripping the parts from the frame to take a closer look. The downtube is bent, but it wasn't immediately obvious, because the bend was actually in the lower head lug. The frame would appear to be toast.
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Old 09-25-16, 09:26 AM
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Well what I did in the past was to replace a down tube with a new one by heating up the lug after I cut the old tube in two and grabbed it with a big vice grip. I had to replace the down tube and the rear part of the lug (it helped me by being put together with silver to start with.)and I removed the lower part of the down tube by the same method. The bottom bracket was pretty strong and did not bend or shift when I heated it up to take off the lower section.

Since I own a Henry James Jig I could hold all of my tubing with correct alignment to start with so I know that the frame was as straight as new or even better when I handed it back to the customer.

Turns out that the guy did it for was a friend of mine so I didn't charge him what I should've. If I had charged him what it cost me to do the job you probably would've cost as much as a new frame.

Mike Frye A.K.A. Frye Bikes
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Old 09-25-16, 09:41 AM
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Thanks, Mike. If any budding framebuilder would like something to practice on, the frame is still hanging on the fence out in the alley, awaiting the arrival of a scrap metal hauler. It's yours for the postage.
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Old 09-25-16, 08:00 PM
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The bulge in the TT and stated bend of the DT suggest a classic head end impact. So check the steerer and blades too. As for merely sleeving the TT- The bulge will need to be dealt with. As the OP is finding out this kind of repair tends to mushroom into a larger one. Andy.
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