Zanella Professionale, my favourite bike of all 9.
lighest, nimblest, comfortable ride I own.
vertical nd seat stay near the dropout.
after



spreading, i can get a fingernail in there.
time to call Marc at Marinoni to get his opinion.

how the f did that happen? crash? you ok?

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gugie bulgie Doug Fattic



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I have fixed cracks like that before, in seatstays, very close to the dropout. The way I like to do it is to widen the crack and file the tubes so that they are square, then make a plug-type fitting that fits into the long portion of the seatstay, and has a tongue shaped end on the other side to engage with the dropout tab. I slot the droput tab and remaining tube still brazed to it, to receive the tongue, making a sort of tongue and groove joint between the plug and the dropout. This renders the remains of the tube that is still brazed into the dropout mostly cosmetic. I spring the seatstay away from the frame and silver braze the plug into the stay. Then I spring it back into place in the dropout/remaining tube and silver braze it into place there. It works. You can also braze it up all at once, but I prefer to do two operations.

No crash, this bike saw only nice weather and inside of the frame was treated with oil film

That's an unusual place for a crack.
Any chrome? I have seen seatstays that rusted out from the inside due to some chrome-plating acid being retained inside. The crack is right about where any little puddle of liquid inside would tend to stay while the bike is 'rubber side down'.

Are there vent holes? Preferably two, near each end, for best flushing of the interior. Even brazing flux is a little corrosive and should be thoroughly washed out.

On two of the frames I saw with the seatstay rotted out from chroming acid, the FB had tried to prevent acid getting in by filling the vent holes with brass braze, but that's difficult to do without leaving a little pinhole or porosity that lets a little acid in, but prevents proper rinsing afterward.

I'm not saying that's a likely cause, just one possibility.

Mark B

Perhaps the DO/chainstay was overheated when brazed in and eventually cracked?

-Kurt

Could just have been internal stresses. The one I made the aforementioned plug repair for, was a bike that was equipped with a coaster brake. The crack was in the seatstay, which I surmised had some internal stress put on it by the coaster brake's reaction arm pulling on the chainstay - putting various loads on the dropout and the seatstay. The same sorts of stresses could potentially occur if the dropout faces weren't parallel but were squeezed together to be so, or if the frame was ridden with a broken axle held together with just a quick release, or even a bent axle, etc.

The bike has no chrome and original paint, no rusting or bubling.
indeed a head scratcher

Vent hole near drop out on both sides, no top vent holes

QUOTE=bulgie;22848371]That's an unusual place for a crack.
Any chrome? I have seen seatstays that rusted out from the inside due to some chrome-plating acid being retained inside. The crack is right about where any little puddle of liquid inside would tend to stay while the bike is 'rubber side down'.

Are there vent holes? Preferably two, near each end, for best flushing of the interior. Even brazing flux is a little corrosive and should be thoroughly washed out.

On two of the frames I saw with the seatstay rotted out from chroming acid, the FB had tried to prevent acid getting in by filling the vent holes with brass braze, but that's difficult to do without leaving a little pinhole or porosity that lets a little acid in, but prevents proper rinsing afterward.

I'm not saying that's a likely cause, just one possibility.

Mark B[/QUOTE]

The spreading did not help.
paint hides cooking of tubes
it is repairable.
Good there does not show a big offset at the fracture, this is beyond a crack.

Repair and or look for an alternate bike.

Try to find a bike mechanic who can do repairs/welding, what steel was it?

Talked to Marc at Marinoni, head fabricator and wizard who did a lot of jobs for me.
repair seems possible or a replacement stay
going down there tomorrow

I wish you good luck ​​​​​​​

Here is where the wizards live.



up above, one the magicians, my go to guy Marc
Here are a few tasty treats:











Update coming