Thanks for photos, how did repairs hold up? For even stronger joints, there are epoxies available from West Marine that's twice as strong as JB. I like to add 30-50% steel powder or filings to increase strength further. To point where you can machine, drill and tap it like metals.
This is interesting as I used to build custom racing bicycle frames. Some questions about failures:
- did any of bracket or tubing break? Or was it just weld?
- at break, did most of weld go with bracket?
- or did most of weld go with tubing?
- did any of tubing bend?
I've got some ideas for improving design and repairing failed joints. Would involve brazing like how high-end custom frames are made. Heat-treated alloys made into thin-wall tubes such as Reynolds 853, Hexcel or Columbus Nivacrom don't react well with elevated temperatures of welding, so they are joined with brass brazing or even lower-temp silver-solder using lugs.