The Sierra Designs Flex Hike 20-30L offers good comfort and features but there are limited external carrying options.
The clue is in the name here with the Sierra Designs Flex Hike 20-30L – a system that allows you to change the capacity from 20 litres to 30 litres. It’s an unusual system with a bellowed gusset that runs the full length of the pack, adding extra width when it’s fully opened.
Peter Macfarlane’s verdict
This is an interesting and unusual pack that I’ve got on well with but do check the fixed back length works for you.- comfortable
- good pockets and features
- capacity adjustment / compression system
- limited external carrying options
- adjustable back length on the absolute limit for my height
| Quick specs |
|---|
| RRP: $149.95 / £150 (available from Decathlon) Weight: 932g Capacity: 32 litres Materials: 100D Nylon Honeycomb/420D Oxford Back system: Contact Stream back system Pockets: accessible side pockets, zipped access lid with pocket, padded hipfins with pockets Features: expandable main compartment, shoulder straps adjustable for height, hydration compatible Sizes: 20-30L capacity, one back size – adjustable Men’s version? Unisex sierradesigns.com |
The adjustment is via three webbing straps at base, middle and top. The base strap is a simple cinch with a ladder lock buckle while the higher two run right round the pack in channels through the fabric and have clip lock buckles which makes adjustment quite easy. This capacity change does put the load further out from your body rather than evenly spreading the weight when it’s at its maximum but at these volumes it doesn’t really affect stability much.
Poles and even ice axes can be stowed securely under the centre or side gusset straps. Also at the sides are mesh pockets which take up to a 750ml bottle and are accessible when wearing the pack.
The back length is adjustable via the shoulder straps which have buckled attachments to shorten and lengthen them. It’s simple and works well with the padding on the back system lining up well enough on both myself at the maximum and my partner at minimum length. The back system is quite stiff which resists deformation when the pack is cinched, and it’s a comfortable carry. The back padding is thick with large gaps so has a good amount of free air space to help with sweat management.
The zipped lid opens from your neck outwards, the opposite to most lids, and works well when you stow gear under the centre straps. It a has a big pocket with two other quite small external zipped pockets. The padded harness is well shaped and comfortable and the hipfins have stretch stuff pockets.
This is an interesting and unusual pack that I’ve got on well with but do check the fixed back length works for you.
Testing conditions
Reserve Ranger Peter rotated the packs on his regular 11km deer fence inspection walks in the Kilpatrick Hills and took them into the Munros through the winter. Peter is 1.8m in height and wears between regular and tall back lengths depending on design and brand.
This review was first published in the August 2025 issue of The Great Outdoors. Compare it with other daypacks in our guide to the best hiking backpacks.
