Originally Posted by DiabloScott

I think you're looking for IBERA

You have to get the rack and pack both, the pack won't fit onto a normal rack. I have tha BA-1 pack and I started with the RA-1 monorack that goes on the seatpost but the weight was too high and so I got the RA-5 rack and really like it... the bottom of the pack is rigid and it snaps onto the rack with one latch - much easier than dealing with a bunch of straps. Went to this system after someone stole my saddle bag with flat tire stuff in it.

AHA, found a photo:


Edit: I see you want the rack to come off easily rather than for the bag to come off the rack easily. Here's the monopost rack I mentioned above...



Again, I didn't like this but it's sturdy and it is pretty easy to take off... just one allen bolt.