That's a good question, and one that I also need an answer to. The rear rack on my bike broke the other day - just fatigue I think.
I'm planning to run a couple of spines down the subframe of by bike, along with some triangulation. I wanted to attach the pannier hoops onto the passenger footpeg hangers...
Difficult to explain, but if you've done the work, did it look like this (extremely amateurish artists impression)?
http://www.ucl.ac.uk/~ucfalmi/FrameStrong.jpg
Linear Mode
