Originally Posted by
cny-bikeman
IF the outside of the derailleur cage is parallel to the chainwheels and the derailleur is only 2-3 mm above the chainwheel and you changed nothing in the back then the only fix is to add a spacer. You might check from the rear to see if the chainline is good by eye from front to rear.
I have a similar issue. When the lower limit screw is at it's loosest and I shift down to the smallest chainring, the front derailleur hits the frame. This is the same front derailleur that came with my bike but I never noticed that clank sound came from the front derailleur hitting the frame.