Our new Sackville series bags are as fine as saddlebags get. The Britamerican materials (including waxed and waterproof cotton duck), the Connecticut craftsmanship, the California design, the melted thread-ends, and the total absence of any cost-cutting measures add up to bags that cost us a mint to make, are worth three mints, but cost you only a mint and a half. They're over-the-top good and a joy to use. They load and unload easier than any saddlebags we've used; they're more secure; they're more handsome.
They are the result of 20 years of nearly daily saddlebag use, for every purpose imaginable, and extensive (and expensive) experience with every top brand made here or anywhere else. There are many fine bags around. None beat this, and only the Nigel Smythes are in the same league (there are many fine bags not as good. These bags are made much better than necessary).
SaddleSack-Medium
Capacity
Not bulged (imagine): 1134 cubic inches, or 18.6 liters (the British way)
Bulged but not ridiculous: 1418 cubic inches, or 23.2 liters
The pocket adds about 50 cubic inches, or .82 liters
This is our most all-around useful biggish saddlebag, just shy of the size needed for bike camping and monstrous loads.
It's about 1,050 cubic inches before you overstuff it, which you can do, easily.
That's big enough for any commuter and wide enough for a MacBook Pro (14.1"), good for general shopping, and packing full of extra clothing on long rides in slurshy weather. It's two inches shorter in every direction than the SadddleSack-Large, and not quite as tall top-to-bottom, so you might not even need a rack or undersupport for it.
Key thing here, the big difference between this and the SaddleSack-Large: THIS ONE IS DESIGNED TO ATTACH TO THE SEAT POST, LIKE MOST SADDLEBAGS. WITHOUT A RACK SUPPORT. So if you absolutely don't ride with a rack and you want a biggish-ol' saddlebag, this is the SaddleSack for you. If you ride with a rack and the size fits your needs, even better.
It has the same flaptop pocket as the SaddleSack Large. The same Scotchlite reflecto-strip, the same flasher light strip, the same side pockets. It lacks the rider-side pockets, because it sits closer to the seat post, and you wouldn't want to stuff them.
If you like bags and aren't already bagged-out, the SaddleSack-Medium is a great bag for sub-stupendous loads. If you don't yet have a saddlebag and are considering your first one, or if you just want to support a small business that, in its zeal to bring you really good products, makes foolish financial decisions related to that.....and if you can handle the purchase better than we can handle its absence, then the SaddleSack-Medium will set a standard that'll be impossible to match.
Approximately 15.25" wide, 8.5" tall and 11" deep.
No rack necessary if:
--You have at least 11 inches of vertical distance between bag loops and tire.
--The bag just barely rubs the tire. And it will, if the saddle-loop-to-tire distance is an inch or two shy of 11 inches. But we've planned for that. There are two D-rings at the outside bottom of the bag to lift the bag up off the tire. Just rig straps or something from the seat rails to the D-rings, and lift. That's their sole purpose. On other big seat bags people've scrunched the bags with wide belts to lift them off the tire. The D-rings we include work much better.
Benefits to using a rack even if you don't need to:
--You can strap or zip-tie the bottom of the bag to it and eliminated 99.009 percent of the swaying. The swaying bugs some people (new to saddlebaggers), but not everybody.
--The rack lets you pull the bag away from the seat post, which means it won't brush your legs as you pedal. "Brushing your legs," sounds worse than it is. I LIKE it. But some people don't, and if you're one of them, just use a rack.
Finally... 
