I'm with the backpackers. I've used several backpacks over the years & have found the best one for me is the GoLite Ion. The only downside to it is that it is just one large pack, with no compartments or little pockets or anything. What I like about the pack is that it is very light, has great shoulder straps & is waterproof. I have several cycling-specific packs as well, but these seem to make my whole back sweaty. The advantage of the Ion (for the way I ride) is that it is kind of slack, so it does not conform to my back. (I tend to pack pretty light-just a change of clothes, cell phone, ipod, bike lock & a book usually). There are plenty of gaps between it & my back, so I usually just end up with a small spot on my back that's any sweatier than the rest of me. The pack works great for carrying my stuff once I'm off the bike though, much better than any Panniers I've tried. I've tried strapping my pack to my bike rack, but so far, no love. The rack straps always seem to be either too tight or too loose. I did find one on amazon.com that gets great reviews and has several pictures that users uploaded showing it carrying backpacks among other things. I have one on order & I hope it solves the backpack to rack attachment problem. If that happened, my golite would be the perfect solution for me.