Originally Posted by
wesmamyke
Not uncommon on entry level bikes to have seamed tubing used in the frame. Meaning it was made of flat sheet steel, rolled into a tube, and welded of course.
The bottom of the bottom bracket shell is the one place they can hide that, and make no effort to clean up the weld.
So how then are the chain stay, down and seat tube openings attached to the shell? I can see no seam that's been welded. Although it looks like the inside has been machined. So I guess the thread material was put in after the shell was machined then threaded.