After testing out my new bender with some hardware store conduit, I bought a couple of 4-foot lengths of 3/4″ dia., .065 wall, 1026 mild steel DOM tubing. The bender did a fantastic job. I got a perfect, kink-free 180-degree bend with minimal time and effort.
However, if you look closely at how it sits on the diagonal frame extensions I machined previously, the loop is about half an inch too narrow. I might fudge it by spreading the loop a bit, or I might do something more precise to make them line up. I still have to bend the front of the loop in 30 degrees on each side and marry them to the existing seat tubes with an internal plug, similar to the way I mated the rear supports to the frame below. I am thinking it will be easier to bend the front tubes separately and then weld them to the loop, rather than bet that i can make three bends all perfectly in plane, then assemble with internal plugs there as well.
I haven’t come up with a way to positively attach the diagonal supports to the loop beyond just gobbing them together with a weld. I have been striving to always build in a more secure, mechanical secondary means of attachment. I won’t have the rear shock mounts to worry about, but some gussets would be a very smart addition. I had been thinking a single 3/16″ triangle along the tube centerlines, lightened with some speed holes. However, now I think a boxed-in or angle arrangement of thinner gauge would be smarter.
