Main tubes are normally about 1mm wall thickness, 3mm seems crazy for an undrilled bridge since the extra metal would sink more heat away from the weld.
Tube wall worn thin and deformed inwards before the first hole appeared? -giving the impression of a greater wall thickness and also providing a backing for a pool of braze?
Main tubes are normally about 1mm wall thickness, 3mm seems crazy for an undrilled bridge since the extra metal would sink more heat away from the weld.