I just put a rack on my bike so I can hang panniers off the back-I need more space than my small messenger bag and don't like the sweat from the strap.
I'm using these bags: Tandem Pannier Bag | Bike Pannier Bag | Shoulder Bag - Timbuk2 Bags
There is a little stretching cord+hook on each bag. I initially stretched them to the bottom of the rack(a topeak super tourist TopeakŪ Cycling Accessories ? Products - Super Tourist DX Tubular Rack w/disc Mounts (w/o Spring) ), at the junction of the front and middle support. But the panniers would fall off.
So I started clipping them to the seat stay instead. No problems on day one, at least. But I'm not doing anything stupid or dangerous this way, right? I figure not, but I'd rather my wheel not fall off in the middle of a ride.
Or if it does, that's something I want recorded, because it'd be funny as hell.