Sackville Backabike Rear Bag, Olive, each
Simple, waterproof, extremely well-made, and more expensive than Ortliebs. SOLD SINGLY, but please get two. It mounts via two small leather buckle straps and a strap (included). It's not the one hand/ one second mount and release of a lot of modern bags, but if you can spare 30 seconds, you'll see the beauty in its simplicity and security, and may have some bonus peace of mind knowing there's nothing to break. They attache to any rack via leather buckles (see last pic in grey). Not plastic auto-open/close German wizardry buckles. They're simple, strong.
Loading and unloading couldn't be easier. The toggle arrangement is wonderful and fast and feels like you're doing a real thing.
Symmetrical shape works equally well on the left or right side and also on the Nitto Big rear, Nitto Big front or Clem racks.
Approx. Dims - 14" x 11.5" x 5" (36cm x 29cm x 13cm)
About ? cubic inches per pair. Let's see, let's figure it out.
14 x 11.5 = 161, x 5 = 805 cubic inches each, or 1610 cubic inches per pair. That is a perfect size for rear panniers. Carry more on top of the rack, and some in front of the bike, and heavens to mergatroid, you should be able to take a good trip with 3,600 cubic inches or so...right? People always bring too many clothes and too much food. Shop along the way, and wear a lot of wool so you don't smell so bad so soon and have to do laundry so often or smell.
NOTE: It seems like a lot for ONE bag, but it's right in there with Ortlieb and other "high end" rear bags. The design is simple—there are no pockets inside, no compartments, no zipper access to anything unseen. You don't need that. In a rear bag, you want it open and stuffable, to maximize the capacity. In rear bags, you carry things you don't have to look for on a ride. Shopping--it's groceries. You don't need to check up on them during the ride home. Touring--it's spare clothing, food, cooking gear, stuff for the campsite. To compartmentalize, use color-coded or mesh stuffsacks for things you want separated. It's convenient and unfussy.