Originally Posted by
jliet
I bought this track frameset recently, and it has a weird weld in the bottom bracket. To me it doesn't make sense - was this done on some BBs or is this just an attempt at a repair job?
That's a bulge-formed bottom bracket shell. It starts out as a piece of sheet metal. Spigots for the various tubes are pressed into the sheet. then the sheet is rolled circular to form the bottom bracket shell and the seam welded closed. The ends of the tube spigots are milled off, and the shell tapped for the bottom bracket cups. On a low-end frame, little or no effort may be spent making the weld seam attractive.