The Marmot Gravitron 58 is a ventilated, internal frame backpack that weighs 2 lbs 15 ounces. It is a combination top loader and panel loader, good for backpacking, as well as travel, because you can quickly access gear deep in the pack without having to pull everything out. The Gravitron is loaded with features including a removable top lid pocket, sleeping pad straps, trekking pole/ice axe holders, and external mesh pockets, that provide a myriad of organizational and storage options. While the Gravitron 58 can hold a ton of gear, heavier loads do result in a noticeable backward pull, characteristic of many ventilated backpacks. However, the pack remains comfortable if you can keep your load under 25 pounds.
Specs at a Glance
- Weight: 2 lbs 15 oz. (3 lbs, actual)
- Removable top lid: 4 oz.
- Gender: Unisex
- Size: One size
- Frame: Internal, ventilated
- Torso: 17–20.5 in (43–52 cm); hip belt sizing: unavailable
- Bear Canister Compatible: Yes, vertical
- Main: 70d Nylon Two Tone Ripstop
- Lining: 135d Polyester
- Reinforced areas: 100d Nylon Triple Ripstop
- Max Recommended Load: 25 lbs
Backpack Organization and Storage
The Gravitron 58 is an alpine-style, top-loading backpack with a twist, because it also has a front panel opening which is convenient for pulling out deeply buried gear, without having to unpack it and pull it out from the top. The top lid is also what’s called a floating lid, that’s attached to the pack with 4 webbing straps instead of being sewn on. This makes it possible to sandwich bulky gear between the bottom of the lid and the main pack bag, an attractive option of long treks. It also means that the lid can be completely removed from the backpack to save weight.
The top lid has a large zippered pocket with lots of space for hats, gloves, and navigation gear. It has an interior mesh pocket, good for storing travel documents or personal effects as well. Unfortunately, this top pocket and the lid flops down over front of the backpack unless the main compartment is stuffed to the gills. It’s awkward and will exert a backward pull if you put too much heavy gear into the top lid.
The Graviton has a front stretch pocket with mesh side panels and side mesh water bottle pockets, which are easily reachable when you’re wearing the backpack. While the pockets are large enough to store two water bottles at once, they’re not very durable and I’d expect them to get ripped up pretty quick.
The main compartment closes with a drawstring, but does not have a speed lid covering to block rain or dust if you choose to remove the top lid. It has a large hydration pocket inside and a single hang loop for attaching a reservoir. A single hydration port is routed between the shoulder straps to run a drinking hose.
The Gravitron also has two hip belt pockets that are large enough to store maps. They’re both mesh faced however and not ideal for storing electronics or other valuables that must remain dry.
External Attachment and Compression System
The Gravitron has an excellent external attachment and compression system, which is ideal if you need to carry bulky objects that won’t fit inside the pack’s main compartment, like fishing rods, paddles, or PFDs.
The pack has two tiers of compression straps with very long webbing straps. These close with buckles, which are easier to use, for attaching and releasing large objects, like snowshoes. The lower tier of compression straps can be routed through or over the side water bottle pockets, which is handy if you want to use them to store bottles and provide compression at the same time.
The pack has a pair sleeping pad straps, permanently attached to the base of the pack for attaching a foam sleeping pad or tent body. This is a feature missing from many backpacks, but a very useful one. In addition, there are a pair of trekking pole/ice axe loops, including top shaft holders, which many packs inexplicably fail to include.
There are 4 extra gear loops around the front mesh pockets and 4 more on the top of the floating lid, providing lots of customization options if you want to attach additional items with your own cord or webbing straps.
Backpack Frame and Suspension
The Marmot Gravitron 58 is a ventilated frame pack with a suspended mesh back panel. The frame is a 360 degree aluminum tube, augmented with a HDPE framesheet that provides excellent stiffness. The cavity formed by the ventilated frame is not excessively deep, but the pack does pull backward when heavily loaded, more so than other ventilated frame backpacks.
The hip belt is sewn onto the pack and provides good load transfer to the hips. The frame terminates in a soft lumbar pad at the base of the pad which is barely noticeable, but helps keep the pack from slipping down your back. While pre-curved, the wings of the hip belt are not heavily padded, something I prefer because I feel they provide a better hip-bone wrap than heavily padded ones. The foam padding is covered with a lightweight mesh with ventilation slits cut into it to help promote ventilation.
The hip belt closes with a single buckle, using a pull forward closure . While there are long hip belt pockets sewn to both sides of the hip belt, they’re faced with mesh, so of limited utility for storing electronics if you hike in a wet climate. Stay on trail with this pack…mesh hip belt pockets are often the first things to get destroyed if you push through waist-high brush and vegetation.
The Gravitron 58 has load lifter straps which are handy for pulling the frame closer to your back if you feel a backward pull. The shoulder straps have a moderate curve, instead of being straight J-straps, so they’ll be more bosom friendly or if you have a well-developed chest. The sternum strap can also be raised or lowered easily on a rail, but this also limits the ease in which you can add accessory pockets to the shoulder straps.
The Marmot Gravitron 58 is a ventilated backpack with the added convenience of front panel access. It has a particularly well-developed external attachment and compression system, with long webbing straps, numerous attachment points, and a floating lid, enabling you to carry bulky gear on the exterior of the backpack. However, the curious thing about the Gravitron 58, is that it you can quickly fill it up beyond its ability to comfortably carry a heavy load, over 25 lbs. The size and depth of the main compartment causes the pack to pull backwards, beyond the normal backward pull typically found on ventilated backpacks. If you still want a ventilated backpack in the ball park of 60L, we recommend you check out the similar ventilated backpacks list below, particularly the Gregory Optic 58 and Osprey Exos 58, which have much better load control than the Marmot Gravitron 58.
Disclosure: The author purchased this backpack.
Similar Ventilated Backpacks
|Osprey Exos 58||$219.99||2 lbs. 11 oz.||Ventilated||48, 58L||Top|
|Osprey Levity 60||$269.99||2 lbs. 0 oz.||Ventilated||45, 60L||Top|
|Gregory Optic||$209.95||2 lbs 13 oz.||Ventilated||48, 58L||Top|
|Gregory Zulu 55||$199.95||3 lbs. 11 oz.||Ventilated||30, 40, 55, 65L||Top, Panel|
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