An innovative lightweight backpack

Sierra Designs is an American company that has been making backpacking gear since 1965 but has never had much of a presence in  the British market. There is now a European branch however and it supplied this pack for test. Why review a pack that you won’t find in any shop here? Because of its provenance and because there was some interest in my doing so on social media. When I looked up the pack to see why people were interested in it I discovered it was designed by ultralight long-distance backpacker extraordinaire Andrew Skurka (just see his list of expeditions to see what I mean – and I was fascinated to discover what such an experienced hiker would come up with.

Firstly, I was surprised to discover that the Flex Capacitor isn’t ultralight. At 1.2kg for the M/L size it is lightweight but there are packs of similar capacity that weigh under 1kg. The frame and the extra weight of a substantial harness mean the pack will handle 20+kg loads, which ultralight packs aren’t designed for, making it suitable for year-round use. The DAC frame is Y-shaped and quite longitudinally stiff. The upper arms of the Y do flex backwards and forwards to allow some give as you move your shoulders. The bottom section of the frame is curved, creating an air gap across the lower back for ventilation. There are well-padded mesh-covered scapular pads, lumbar pad, shoulder straps and hipbelt. The last is made from two densities of foam – soft on the inside for comfort and so it moulds to the body and stiff on the outside for support. This is a very supportive harness that carries the load well. It’s not quite as stable on rough ground as a body-hugging pack but it is better than most packs with sprung frames and it does keep your back fairly dry.

The packbag has some unique features, the main one being the variable capacity that gives the pack its name. There’s a full-length gusset on the front with four straps running across it. Open these up and you have a 60 litre pack, tighten them and it’s reduced to 40 litres. There are also side straps that run right across the pack that can also be used to pull the pack in around the load. This is the best system I’ve seen for reducing the volume of a pack. I would like the side straps to be longer though as they’re too short for attaching a bulky item like a foam pad when the pack is full.

The lid is unusual too. Rather than fastening with straps and buckles it simply zips round. There’s no inner flap or even a drawcord so access to the contents at the top of the pack is excellent. There is a pocket on the lid, which is good for small items. Put bulky items in and it intrudes on the capacity of the main bag though. As it is I find that the ease of access to the main compartment is such that I treated the top of it as though it was a pocket. There are three drawbacks I can see to this zipped lid. Firstly, although there’s a narrow covering flap it’s not waterproof. Water-sensitive gear needs to be in a waterproof liner or drybag. Secondly, if the zip fails the lid can’t be closed. It is a substantial zip and failures are very rare these days. I guess if it did break safety pins could be used to hold it shut. And thirdly, you can’t increase the capacity by raising the lid as you can with ones that attach with straps or carrying something across the pack under the lid. Once the pack is full any extra items have to go on the outside.

The pack has five other external pockets. Two mesh lower side ones accessible when wearing the pack that will just hold litre water bottles, two roomy zipped hipbelt ones, and a stretch mesh one on a shoulder strap that will hold a small water bottle, smartphone or GPS. Inside there’s a removable reservoir pouch. There’s no front pocket due to the compression straps.

The pack is made from tough feeling 100D nylon-polyester ripstop with 420D nylon Oxford in wear areas. There are two back lengths, S/M and M/L, and four hipbelt sizes. The S/M capacity is 39-56 litres, the M/L 42-60 litres.

Using the pack I was impressed with the load carrying capability. With 15kg in it feels very comfortable and well within its limits. Ventilation is good, which is great in hot weather, but a cold wind can whistle through that gap and give you a cold back. The compression system works well but I did miss having a big front pocket into which I could shove a wet shelter or waterproofs and use for items needed during the day. I could get used to not having one though – most of the packs I’ve used on long-distance walks didn’t have one – especially as the zipped top gives such good access to the main bag. Overall I think this is an excellent pack well-worth considering for year-round backpacking. It would be good if someone would stock it in the UK.

€220  (£197)