Under normal circumstances I am a cycling minimalist, i.e., I don’t carry much with me on a ride except for a small bicycle mini-tool, tire boot, a can of compressed air and a spare tube. However, I had to make some adjustments a few months ago when I bought a Surly Necromancer Pugsley and had a Shimano Alfine 8-Speed Internal Geared Hub installed on it. The Pugsley in an awesome Fat Bike, but a spare 26 x 4.0 inner tube is enormous and will not fit in a standard bicycle saddle bag. In addition, the Alfine hub pretty much demands that you carry a pair of needle nose pliers with you for when have to remove the rear tire to fix a flat. Because the Alfine hub is only available as a bolt-on (no skewer) you also have to carry a short 15mm box wrench! It took me a while to find a seat bag that would hold everything I need, but the Topeak Aero Wedge Pack Saddle Bag holds all I need and has room to spare (it is an expandable bag).
The large Topeak Aero Wedge Pack Saddle Bag is made of 1200 Denier Polyester with a Dupont Teflon coating and has an internal storage capacity of 90–120 cubit inches (this bag is also available in two smaller sizes as well). The bag measures 9.1″ x 5.1″ x 5.5″ and weighs just under six ounces. You attach this bag to the rails of your saddle with two nylon straps that have fast release buckles—there is also a Velcro strap that wraps around your seat post. The back flap on this bag has a slot so you can clip on a taillight, and above the slot is a large 3M reflective strip (one of the largest you will find on a seat bag).
I used this bag all winter and it held up well to snow and ice. However, I did have a problem once the snow on the trails turned into mud. My Pugsley has very wide knobby tires (Surly Nates) and they kick up so much mud that words defy description (see photo above). While the mud washed off the bag fairly quickly, the zippers were so clogged up that I could not get the bag open. Even after several thorough cleanings with soapy water and brushes the zippers still won’t work smoothly, and I can’t find any sort of lubricant that helps. Therefore, while I would highly recommend this saddle bag for most conditions, if you ride on muddy trails you really need to either find a different saddle bag or at least wrap this on up with something like Saran Wrap. At the moment I am testing a Topeak Wedge DryBag, but have not used it enough to offer an opinion on it yet.
The Topeak Aero Wedge Pack Saddle Bag retails for $28 and should be available at your local bike shop.