The front frame is aluminum, the rear suspension is steel.
The aluminum welding is almost as strong as mild steel...so better than tig (my opinion).
Bike is experimental and took a while to work out the bugs.
Now that it's reliable, I will tear it down, clean it up and paint it.
No issues with the china chain...just keep it well lubed and it works fine. I use Rustcheck. keeps it lubed and rust free.
Check out these links for more info on aluminum welding:
YouTube - welding aluminium part 1
YouTube - Welding aluminium Part 2
YouTube - Welding Aluminium Part 3
YouTube - Durafix - 6
YouTube - Aluminum-Repair.wmv