Since I co-developed the Flex Capacitor with Sierra Designs, naturally I want to see strong sales of it. But I also want prospective buyers to understand its optimal applications and tradeoffs, and ultimately find the best backpack for them. All else being equal, I hope you will support my forthrightness.
1. Limited sizing and color options
A limited production run will become available in October, directly from Sierra Designs. Sign up for updates. It will come in one color scheme and three unisex torso-length sizes (S, M, and L).
The color option will not change for retail distribution in spring 2017, but sizing will. It will consolidate to unisex S/M and M/L, which will still have 3-inch ranges but which will cover most of the market with one less SKU.
These limited sizing and color options will limit interest in the Flex Capacitor, especially among women and among men with very short or very tall torsos. But due to SD’s newcomer status and to the state of the retail backpack market (i.e. dominated by Osprey, with a few pegs leftover for everyone else), SD believes that a tight assortment is its best hope of gaining a foothold.
2. It’s not “ultralight.”
With relative ease, we could have substantially reduced the weight of the Flex Capacitor, which currently specs at 2.5 pounds (1.1 kg). How? Mostly, by:
- Eliminating its full suspension, back panel padding, and hipbelt;
- Removing its six exterior pockets;
- Using a lighter weight fabric; and,
- Shrinking its volume, or at least making it static (rather than adjustable).
These actions may have pleased the thru-hiking community, BPL forums, and r/Ultralight, but it would have left the broader market longing for more. Frankly, I’d be looking elsewhere, too. IMHO, the extra 16-24 ounces is well worth the improved load-carrying performance, convenience, durability, and versatility.
3. No rear shove-it pocket, sleeping bag compartment, or tall side pockets
The single most standout feature of the Flex Capacitor is its adjustable volume, using the gusset on its frontside. Unfortunately, this feature is incompatible with a rear shove-it pocket and a sleeping bag compartment.
Shove-it pockets compromise load-carrying performance (because the weight is far from the user’s center of gravity, and often sits outside the compression system) and are abrasion-prone if made of mesh. When using the Flex Capacitor, I store oft-needed items in exterior pockets or at the top of the main compartment (easily accessible via the zippered top lid); and I store wet items like my rain gear and tent fly inside the main compartment but outside my pack liner.
I struggle to see the case for sleeping bag compartments, and wonder if they are just a relic from a bygone era when sleeping bags were much less compact. When I pull into camp, everything must come out of my pack — shelter, food bag, stove, puffy layers, etc. Why is a second access point supposedly more convenient?
Finally, tall side pockets are not accessible without taking off the backpack. At that point, why store items outside the pack, when they would carry better and be more secure inside the main compartment?
4. Lack of “wrap”
Frameless backpacks fit like a glove — they conform to the user’s back, not the other way around. Unfortunately, frameless packs cannot comfortably carry loads of 25-ish pounds or more. To carry more weight, you must use a full suspension backpack.
Whether in a frameless or full suspension pack, weight carries best when it is flush against the back, so that it minimally affects the user’s center of gravity. Unfortunately, this direct contact results in SBS, or “sweaty back syndrome,” especially in hot and humid conditions.
To avoid SBS, there must be airflow between the user and the backpack. Unfortunately, this pushes the load backwards and compromises load-carrying.
See the tradeoffs?
The Flex Capacitor is a full suspension backpack with decent airflow around the kidneys. But it does not “wrap” the user like a frameless pack will, and its load-carrying is not at max potential. Further refinements to the back panel pods and hip belt may improve things.
5. Stretch mesh side pockets
The side pockets on early Flex Capacitor prototypes were made of durable pack body fabric. They were easily accessible and could be locked off when bushwhacking. But their bulbousness ruined the pack’s otherwise “clean” look, and the lock-off was clumsy.
The side pockets are now made of stretch mesh. They look much cleaner, and they are still easily accessible — they have some dimension, and are not flush against the pack body. However, they will be more abrasion-prone, even though we’re using the heaviest mesh available, and there is no security feature.
6. Top lid zipper snags and aesthetics
The Flex Capacitor’s main compartment is accessed through a zippered top lid. Getting in or out is refreshingly quick, relative to the sequence of buckles, straps, cords, and roll-tops on most packs.
However, it’s not entirely annoyance-free, as the #10 zipper can snag on the rainguard. We could have eliminated the rainguard by using a watertight zipper. But such zippers are:
- Less durable
- Less easy-gliding
- Not waterproof in extended wet conditions
Plus, we didn’t want to give the illusion that the pack is waterproof when it is not. To keep dry items in the main compartment, I recommend using a 20-gallon Brute trash compactor bag.
Unless the pack is stuffed full, the top lid will sag and “mushroom.” It’s merely an aesthetic issue, and common among packs with top lids.
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