The Symbiosis Gear Aspen UL backpack is an ultralight, frameless backpack designed for women by a woman. This makes it unusual in the world of ultralight backpacks, where most packs are unisex. This mostly means they are made for men.

• Type: Frameless
• Voume: 48L (38L main, 10L external pockets)
• Weight: 25 oz/ 708 g
• Gender: Unisex but made for women and those with narrow shoulders, with S-shaped shoulder straps
• Pockets: 5 open
• Waist belt pockets: No
• Hydration compatible: No
• Load lifters: No
• Maximum recommended load: 20 lbs
• Sizing: One size
• Materials: 420D Extreema (Nylon), Spundra UHMWPE
• Fit: 5’2” to 6’1” height
• Hipbelt range: 18”-50”

Backpack Storage and Organization

The top Y strap is the best place to attach a foam pad

The Aspen is a top-loading backpack with a total capacity of 48 liters. This includes 38 liters of internal volume and 10 liters in the external pockets. The pack bag has a roll top with snaps for closure and a Y-strap to hold it down.

There are five open pockets: a large front stretch pocket good for storing stuff you need easy access. There are two large side pockets made of solid, durable 420D ripstop nylon fabric. It is possible to grab a water bottle from the side pockets and put it back in. It can be done with a Nalgene, but it’s much easier with a tall bottle with a smaller diameter, such as Smartwater or a similar brand. One pocket will hold two such bottles or one bottle plus other gear. Both pockets have a cord-locked shock cord on the opening.

There is a fourth pocket on the bottom of the pack. It is the same stretch fabric as on the front pocket. It could be a good place to put a map, a sit pad, or a bandana. Also, anything inside it can get squished when you set the pack down. This pocket is most secure when the pack is full, but it’s not a good place to keep valuables.

The fifth pocket is an integrated stretch phone pocket on the right shoulder strap. I was initially skeptical about this pocket, but it holds onto my phone quite well, and it doesn’t impede shoulder movement.

The Aspen phone pocket holds a phone securely

You can fit a full-size bear canister vertically in the pack, then pack around it. However, this takes up a significant amount of the usable interior space. It is recommended that you add a sit pad to the back for padding. You could also put it on top using the Y strap; however, you would probably want it empty or filled with light things, rather than adding a large amount of weight high up on the pack and throwing off your balance.

There are no pockets on the waistbelt. However, a detachable pouch is in the design phase at Symbiosis Gear.

Backpack Frame

The back panel is covered in breathable mesh

The Aspen is a frameless backpack with a padded mesh back. The pack is outfitted with female-friendly S-curve shoulder straps. I found them quite comfortable, and they should fit any breast size. The sternum strap is very easily adjusted along the shoulder strap. Part of it is stretchy so that you can get a firm yet forgiving fit.

The Apen does not use load lifters, and they’d be pointless on a frameless backpack anyway because there’s no frame to anchor them to. When packing the pack, you want to make sure you don’t oversuff it so it barrels against your back but lies flat against it.

The waist belt is simple 1.5” webbing, so it does not transfer load to the hips. The buckle lies nicely flat and is easy to operate. Wide elastic bands wrap around the belt that you can use to manage any excess belt webbing

External Attachment and Compression

The Aspen has zigzag side compression straps that run the length of the pack and can also be used to attach items to the sides. There is not much excess length, so it’s difficult to attach anything bulky. There is a long Y-strap that can be used to compress the top of the pack or to secure a bulky item, such as a foam sledding pad.

In addition to shock cord over the front stretch pocket, there are gear loops at the base of the pack to facilitate carrying trekking poles. There are also daisy chains on the shoulder straps for attaching accessory pockets.

The back panel is covered in breathable mesh

Maximum Recommended Load

The Aspen is rated for 20 lbs, and when I go over that, it becomes uncomfortable. Ideally, you’d want to get your base weight (minus food, fuel, and water) down to around 10 lbs and carry a minimal load to fit into the pack’s 38L of closed capacity and 10L of open pocket space. That’s a pretty minimal summer load by my standards, with few nice-to-have comfort items. While the Aspen is a backpack designed for women, you’ll want to shrink your load volume and weight substantially to use it comfortably, particularly if you use a backpack with a frame and hipbelt today.

Recommendation

The Symbiosis Aspen is an ultralight frameless backpack designed for women. With a total capacity of 48 liters (38L of closed storage), it’s primarily designed for thru-hikers who want a durable ultralight backpack made with thick nylon (Extreema) rather than more expensive Dyneema or Ultra fabric. That said, the Aspen would also make a nice pack for shorter-duration or weekend backpacking trips, provided you can keep your total pack weight under 20 pounds.

Disclosure: Symbiosis donated a backpack for review.

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