Here is a Motobecane 40T Frame. The stock frame is rigid and could be easily bent. I traced out the pieces by making cardboard templates and then transferred them to sheet metal. Then I cut the sheet metal out with a cut off wheel. The sheet metal was then clamped in place. I borrowed one of my friends MIG welders for this project and it was kind of hard to adjust properly for the size of sheetmetal (cheap welder). I tacked everything in place and then burned it all together. The welds need to be reground, primed and painted from here, but the swingarm should be much stronger now.
Motobecane 40t Frame