Side pockets which are easily accessible on the go and large enough to carry a significant percentage of the days gear (water, food, rain gear, maps, etc) are the defining element of a modern backpacking pack. Belt and shoulder strap pockets can play supporting roles here, but my last three years of testing has heavily reinforced my conclusion that here is no substitute for good side pockets on a mileage-oriented pack. How did we manage for so long without them? Slower and less efficiently. Just look through this post and cringe.
That said, there are plenty of reasons to try to get along without them if at all possible. Proper side pockets aren’t at all complicated pieces of design, but getting the details just right is fiddly. The deeper reasons for avoiding them have to do with the more rugged and technical pursuits. Backpack width is the most premium number in balancing capacity and performance, and good side pockets necessarily add a lot of this, usually 3-4 inches per side. A 12 inch wide pack, the limit for conventionally sized adults wanting a sleek pack, could easily grow past 20, which can be a problem in brush and while nordic skiing. Side pockets also don’t play well with things like a-frame ski carry, at least without making the pocket design more complex and heavy still.
Another limitation of side pockets is their gaping opening, which while bushwacking, hiking in the rain, and crashing on skis become magnets for pine needles, water, and snow. Pocket security is also a consistent issue, the number of water bottles and cans of bear spray lost during the Bob Open to wrecks, creeping willow branches, and logpile gymnastics is easily in double digits, something that isn’t just an inconvenience, but potentially a safety concern.
When I started developing a pack targeted at trips like the Bob Open pocket accessibility and security was right up with load carriage on my list of problems to understand and find balance for (aka “solve”). The first prototypes sought extra pocket capacity and utility by extending the pocket out on to a wing which cinched to the hipbelt. One had a zipped closure, the other a flat zippered pocket inside the bellowed cinch-cord pocket. These pockets worked well, but didn’t make the cut for a number of reasons. One, they’re a serious pain to sew, and extending the pocket on to the wing doesn’t add enough function to merit the added complexity. The zippered security was nice, and it is very possible to make a zippered pocket that is easy to open and close with one hand, so long as the pack is full, if you extended the zips with wings. The zips become mostly if not entirely unusuable with a partially empty pack. They’re also a long term durability concern, even with #10s, and in winter the zips can freeze up.
About that accessibility; there is a narrow window of efficacy with side pocket dimensions. Assuming fairly conventional pack width and a bag that doesn’t hang too far down from the illiac crest, anything beyond 7 inches of depth demands more than most folks shoulder flexibility will allow. Much less than 6 inches of depth makes for a pocket that gives up capacity. The obvious answer is to extend the pocket all the way to the base seam, which is what I’ve been doing on all the recent prototypes. Bumping the base of the pocket up the side panel a hair is tempting, as it enhances abrasion resistance, and a straight base line is the ideal in functional capacity, but in the end more space is better, simpler, even if un-ideal in some ways.
MLD and HMG are the top examples (with pockets that are identical in function if not construction) of a simple design that prioritizes durability over function, with flat, pleated side pockets elevated above the base. MLD is on record as endorsing the loosen the straps and cant the back off the belt approach to bottle grabbing, with the physics being undeniable and the coherence, in situations where you don’t want to go for the flop, rather lacking. Gossamer Gear has long been the other side of the coin, with the Gorilla (for instance), having dimensioned (i.e. 3D patterning) pockets right at the base. These work a lot better than any flat pocket.
The answer to abrasion concerns with low pockets are to pack side pockets intentionally, which occasionally means leaving them empty, as well as using appropriate fabrics. The 140D gridstop on the old Gorilla was, for instance, too light for my taste even for trail backpacking. I discovered early in the pocket process that it is possible (easy, on a pack 8 inches or more deep) to make a side pocket too big. The trick on the Tamarisk (7 inches deep at the base) was to make pockets that could hold a 48oz nalgene and sundries, while also collapsing mostly flat when empty. Dimensioned pockets have been the only way to make full use of pocket real estate since the side pocket revolution got going, but with the Tamarisk I reverted to a hybrid style.
Against the user they’re dimensioned, and 4 inches deep, while the non-user side is flat, the excess depth of the pocket taken up in two pleats sew into the seam. The curves of this seam goes both upwards and inwards towards the users spine, in both cases just enough to make for smooth edges without blunting functional capacity (more in the next installment). The way the pleats limit pocket capacity ends up blending with the dimension of the main bag, creating a pocket that if big, but mostly disappears when needed. The finishing touch is doubled shock cord, whose tension is adjustable on the fly (shout out to Luke Fowler). In use tension is high enough that the pocket can almost be sealed shut, while maintaining easy accessibility, and with the perishable elements being user replaceable.
Alpine packs won’t and shouldn’t have side pockets, for the reasons listed above. But if the wholistic mission of a backcountry pack is limited to 4th class and below, be it on rock, snow, or in the bush, side pockets are a necessity, as the best way to maintain efficiency and keep hydration, nutrition, and day gear close at hand. As a process they embody well the compromises that shape every aspect of a technical, multiday pack.