Tom Ritchey produced TIG-welded frames by at least the mid-80's, I believe. I used to own a circa-'89 Road Logic (Tange steel tubing) TIG welded frame built specifically for racing. Clearly not on-topic, unless you count it under KOF. My guess is that he didn't do that welding himself, but I could be wrong.
I'm sure that's not the earliest example of steel TIG welding, but if it turns out to be close I'll do more research (no charge, of course!).
I would imagine that there are many aluminum frames that meet Kurt's criteria.
Dave Ross Portola Valley, CA
Kurt Sperry asked:
When was the first TIG welded (or other inert gas-arc welded) lightweight road racing frame built? Any on topic?