Most steel frames featured brazed lugs. A few Miyata models were welded. For 1983, the first year, the RidgeRunner frame was partially welded, partially fillet brazed.
For tubing Miyata used Miyata FM-1 HardLite SpiralSpline Triple Butted Crome Molybdenum. Hello, you are still there? Besides this was Miyata's way to express they use high quality steel all those definitions mean something. SpiralSpline for example is spiralshaped butting. On right you can see a TT pictured. Click pic to enlarge.