If I don't stay in top of keeping my rear disk clean it can get quit loud too.
It's weird that 3 bike shops can't figure out a derailer... It's not that hard. Type in the name of your components on YouTube and you'll be able to adjust it yourself!
I believe the standard freewheel is from Sunlite which under warranty was replaced with the same crappy freewheel.Gus: Is the freewheel just a standard Shimano cassette replacement? Is it something end use swappable (yes I enjoy tinkering with my ST1)
I also changed the rear tube to a thick mountain tube.