Originally Posted by
CliffordK
What if one just cleaned it up and rewelded. Grinding down the original weld some (V-grind the crack if possible). Especially grind a V in the gusset.
It may not bring the frame back to 100%. I wouldn't do competitive cyclocross on it. However, it should be usable for typical city/commuter riding, and certainly could extend the life of the frame for some time.
Personally I have troubles getting a good weld in a deep V between tubes, and that could be a weak spot, although the gussets should help.
On the right side, the crack does deviate from the head tube, but still should be weldable,and still should be within the double butting if the tubes are double butted.
It can be rewelded fine IMO. But what you would do is cut out the whole TT and sand the HT and ST ends back to smooth metal. No grooves or anything, just get rid of the entire original tube and the welds. Since both those tubes are quite thick (HT probably 1.3mm, that ST lug probably more) there's plenty of good metal to weld to. Then just mitre a new tube and TIG weld it in and it will look like new.
You can see Brodie did this with some CS:
The BB shell is also thick enough to just grind it back and reweld onto it. In fact with the exception of where the ST joins the ST all the joints on a bike frame are thin to thick and the thick end will stand rewelding.