What you're doing looks similar to what I had in mind for my bike. Is that conduit you're using, and are you brazing the tubing instead of arc welding?
Correct. I'm using 1/2 EMT conduit. EMT is specified as "mild steel" so you won't get performance like 1020 DOM tubing. This means that whatever you build is going to be heavier for a given design load (ie: you'll use more material to achieve the same strength.)
Like DOM, EMT is formed and welded, though DOM generally has the seam ground away while EMT has a seam you can feel on the inside of the tube.
I'm using an air-acetylene torch and flux coated brazing rods. I hand notch all the joints and use the torch to create a generous fillet. I'm confident that the joints will fail after the actual EMT.
*** WARNING ***
EMT is galvanized on the outside and in many cases as an organic coating on the inside so be very very careful when working with it.
Know the symptoms of zinc poisoning and understand how to reduce your risk of exposure to fumes.
I do all my work outside and try to stay well upwind.
*** END OF WARNING ***
EMT is just fine, provided you don't mind the weight penalty and limits imposed by conduit benders (5" diameter bends.)
I'd love to be building with DOM and have a TIG welder, a real pipe notcher (actually a bandsaw and a jig would be better) and a real tubing bender.
These things cost money and take up space, neither of which I have much of right now so for the cost of EMT @ 1.95/10 feet and acetylene & brazing rods I'm pretty happy with it.
It looks great! I'm not really planning on a luggage rack, but I am planning on building pannier racks to add some Ortlieb QRL waterproof saddlebags from Aerostich. What are you using for your mounting points?
My rack attaches to the four grab-rail mounting points. I used angle iron & round bar to create lugs that the tubing slips over, and then brazed the tube to those lugs.
The pannier racks currently attach to the shock lugs and bolt to the front rack mounting lug. I need to add an additional mounting leg on each side to connect them to the passenger footpegs. I've got the flat stock mounting points installed but need to cut and bend them a little to allow the slotted round bar mounting lugs to be mounted in the right position.