The original Sierra Designs Flex Capacitor backpack has performed and sold well since it was released three years ago. So Sierra Designs recently expanded the Flex Capacitor series with two new editions, while also updating the original.
I was involved with the design and launch of the original Flex Capacitor. But I haven’t been affiliated with the brand for nearly two years, and did not help with the development of these new and updated models. Last spring I visited the local Boulder office to get an early preview.
Preview: Flex Capacitor 25-40L, 40-60L, and 60-75L
The three-pack lineup now consists of:
- New: Flex Capacitor 25-40L ($180, 2 lbs 7 oz/1.1 kg), best for thru-hiking and overnights/long weekends;
- Updated: Flex Capacitor 40-60L ($200, 2 lbs 9 oz/1.16 kg), still the sweetspot of the line, and best for 5- to 10-day trips, bear canisters, and colder/stormier conditions; and,
- New: Flex Capacitor 60-75L ($220, 2 lbs 10 oz/1.19 kg), best for winter backpacking and the family pack mule.
All three models are now available. It’s difficult to launch a summer product in October, but at least they’ll be available for holiday shoppers and thru-hikers this winter.
The new Flex Capacitors will be available in just one or two sizes, with each size accommodating a 3-inch range of torsos. (To measure your torso, watch this video.) The limited sizing will compromise sales, but may have been necessary if sales forecasts did not exceed factory minimums. If the packs catch on, Sierra Designs can add sizes later.
- 25-40L: S/M (16″ to 19″)
- 40-60L: S/M (16″ to 19″) and M/L (18″ to 21″)
- 60-75L: M/L (18″ to 21″)
Each model is available in two hipbelt sizes:
- S/M (29″ to 32″)
- M/L (32″ to 35″)
What’s the same, what’s new?
The basic aesthetic and core feature set of the original Flex Capacitor was extended to the new models, and is largely unchanged. Expect:
- Gusseted front panel that can be collapsed or expanded to uniformly adjust the pack volume;
- Durable all-nylon construction;
- Multiple and functional exterior pockets;
- Two horizontal compression straps; and,
- Robust suspension system with a comfort capacity much greater than the average 2.5-pound backpack.
The updates to the Flex Capacitor are mostly small or behind the scenes:
- Two color options: Birch, an off-white, and Peat, a dark gray;
- A second shoulder strap pocket was added, bringing the total number of exterior pockets to seven.
- The internal hydration sleeve is double-duty: it can be used as an exterior mesh “shove it” pocket, the lack of which was a common complaint (among non-owners, at least).
- The pack bottom fabric is the same 420d nylon oxford, but the body fabric was switched to a silicone-coated 100d nylon-polyester rip-stop with better tear-resistance.
- The anchor stitching for the volume adjustment straps was improved, to prevent tear-outs.
- The hipbelt was redesigned for simpler manufacturing, but its performance should be about the same.
I was disappointed that the harness was not more fundamentally designed, so that it more consistently wraps around the body. Currently, there’s a “wedge” between the hipbelt and lumbar pad. The problem is not exclusive to the Flex Capacitor — my ULA Catalyst shares the same flaw. This redesign would have required more time and testing.
Note that the 25-40L and 40-60L use the same 8-mm aluminum Y-shaped stay, while the 60-75L version was spec’d with a stronger 9-mm version. Given the higher expected loads for this model, that seems appropriate, but I wonder if a tougher pack body fabric should have been used, too (e.g. 200d instead of 100d).
Leave a comment
- What questions do you have about the Flex Capacitors?
- What do you think of the updates and the new models?
Disclosure. I strive to offer field-tested and trustworthy information, insights, and advice. I have no financial affiliations with or interests in any brands or products, and I do not publish sponsored content
This website is supported by affiliate marketing, whereby for referral traffic I receive a small commission from select vendors like Amazon or REI, at no cost to the reader. As an Amazon Associate I earn from qualifying purchases.