Review: Gregory Optic 58 and Octal 55 Ultralight Backpacks

Ultralight Backpack
Gregory Optic 58 (men’s) and Octal 55 (women’s)
$210, 58L/3,539 c.i. (men’s medium), 2 lbs. 7 oz. (men’s small, without the included rain cover, 3 oz.)
Sizes: men’s S-L, women’s XS-M

No one loves loading extra water into their pack—especially upwards of 13 pounds of it, as I did as we left our last water source on our final evening backpacking the Grand Canyon’s Thunder River-Deer Creek Loop. We needed to haul enough liquid sustenance to get us through the 2,600-foot climb we were embarking on at 5:30 p.m., plus another 2,000 feet uphill early the next morning. That pushed my total pack weight up toward the limit of the ultralight Optic 58—as good a test as any. And Gregory’s first foray into ultralight packs not only handled that assignment well, it shines for many other reasons, too.

The men’s Optic 58 and women’s Octal 55 (plus smaller-capacity versions of both, the men’s Optic 48 and women’s Octal 45) represent the first ultralight packs from Gregory, a brand known for high-end comfort and design, especially in its packs built for big loads, like the men’s Baltoro and women’s Deva series. Having used many Gregory models, I was eager to take the Optic 58 out for four days on the rugged, 25-mile Thunder River-Deer Creek Loop off the Grand Canyon’s North Rim in May. I carried 25 to 30 pounds for much of the trip, but a maxium of about 35 pounds for more than two hours, including that six liters of water to our final, dry camp.

Gregory Optic 58 back panel and harness.
Gregory Optic 58 back panel and harness.

The frame, an aluminum perimeter wire with an HDPE framesheet, has very slight flex to it, which results in better support and torsional stability at the upper end of the pack’s weight capacity—30 to 35 pounds—as well as a bit of bounce, especially when hiking downhill or at a stronger pace. But you’ll get a little bounce in other ultralight packs, because the whole idea is minimizing weight, which is the best way to make a load more stable (and not bouncy). The fixed (non-adjustable) harness comes in three sizes, fitting torsos across a range from 16 to 22 inches in the men’s Optic and 14 to 20 inches in the women’s Octal; most people would find a size that fits. While I’ve worn a men’s medium in other Gregory packs, the men’s small Optic fit my 18-inch torso well, even though I’m on the cusp between men’s small and medium.

Gregory’s trampoline-style Aerospan suspension consists of a tensioned, highly ventilated back panel with side openings, that’s suspended slightly off the pack bag, to allow air movement across your sweaty back; that makes a difference in comfort on strenuous or relatively fast hikes and hot weather in places like the Grand Canyon. But because the pack bag rides fairly close to the back panel and the frame transfers weight very efficiently to the hips, I never got the feeling of the pack hanging off my shoulders. Even with a full, three-liter water sack far from my spine in the pack’s front pocket for a steep, 2,000-foot uphill slog, the pack still carried reasonably comfortably.

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Gregory Optic 58 hipbelt.
Gregory Optic 58 hipbelt.

The very breathable, perforated foam in the shoulder straps, leaf-spring lumbar pad, and hipbelt softened the heaviest loads I put in the Optic 58, distributing the weight nicely and never causing any pressure points. Still, this is an ultralight pack with a comfort limit of 30 to 35 pounds; pushing that capacity will overload the flexible hipbelt and the suspension.

Gregory Optic 58 front.
Gregory Optic 58 front.

Backpackers who want to go ultralight without switching to a more stripped-down style of backpack will like the traditional design of the top-loading Optic and Octal. A wide mouth and white interior make for easy access and good internal visibility when loading and unloading. There are six external pockets (I’m not including the zippered pocket on the lid’s underside because it’s not technically “external”): two zippered pockets on the hipbelt that each hold two or three energy bars (but not a large smartphone); a zippered lid pocket with the kind of space you’ll find in other packs in this category; two stretch-mesh side pockets that hold a liter bottle; and a large, stretch-mesh front pocket that will hold a wet rainfly or, as I found, a three-liter water bag.

I found the side pockets a little difficult but not impossible to reach while wearing the pack. The three external mesh pockets suffered no damage from the abrasive rock in the Grand Canyon, but I was careful with it; that mesh will tear easily if you’re not careful. The pack bag fabric is otherwise moderately durable 100-denier nylon with 210-denier nylon in the bottom—comparable to many lightweight packs.

Removing the two-pocket lid reduces weight by only three ounces, not much weight savings for sacrificing the organizational convenience and capacity of those pockets; plus, replacing it with the all-weather rain-and-dust cover (included) over the main compartment means you shave only two ounces. The ostensibly floating lid extends by only about an inch if you want to supersize the load—limiting the ability to overload the pack and make it top-heavy.

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Gregory Optic 58 hipbelt and side pocket.
Gregory Optic 58 hipbelt and side pocket.

The Optic and Octal also sport some basic, utilitarian features found on heavier, traditional packs. Front attachments hold trekking poles or ice axes. Adjustable Z-compression straps on both sides and top compression on the main compartment shrink the pack bag for stability when it’s underfilled, and the side straps held a short foam sleeping pad. There’s an internal bladder sleeve and hose port, of course. And the left shoulder strap has an elasticized strap for holding sunglasses or trekking poles—useful for hands-free photography or scrambling without stopping to remove the pack.

While adding organizational convenience, those pockets and other features also add about a half-pound compared to more-streamlined ultralight packs like the Hyperlite Mountain Gear 3400 Windrider and the Gossamer Gear Mariposa 60.

The smaller men’s Optic 48 and women’s Octal 45 ($190) sacrifice significant capacity for the nominal benefits of shedding a few ounces and dollars.

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Gregory Optic 58 and Octal 55


The Verdict

The Gregory men’s Optic 58 and women’s Octal 55 are well-designed, comfortable packs for ultralighters who want some organizational features of traditional backpacks and the support to carry 30 pounds or more.



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See all of my reviews of backpacks, ultralight backpacks, backpacking gear, and ultralight backpacking gear at The Big Outside.

See also my “Top 5 Tips For Buying the Right Backpacking Pack,” and my stories “Gear Review: The 10 Best Backpacking Packs” and “Ask Me: What’s the Best Ultralight Thru-Hiking Backpack?

NOTE: I tested gear for Backpacker Magazine for 20 years. At The Big Outside, I review only what I consider the best outdoor gear and apparel. See categorized menus of all of my gear reviews at The Big Outside.

—Michael Lanza


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Leave a Comment

5 thoughts on “Review: Gregory Optic 58 and Octal 55 Ultralight Backpacks”

  1. Hi,
    Just wanted to post an update on the Gregory Optic 58. Per Michael’s advice on size (we are the same size and build) I went with the Optic in a small, and it fits perfectly. If you’re over 5’8″, get the medium.

    As is the standard with Gregory, the suspension really can carry the recommended max load and even a bit more. I’m a fan of putting most of the load on my hips for a long climb. The air mesh really does work at keeping my back cool while allowing the load to stay close to the center of gravity.

    It has been a very rainy summer in the Blue Ridge mountains this year, so having a rain cover has become standard daily wear. Smart hikers will use a pack liner as well to insure dry gear.

    The pack side pockets don’t seem quite as easy to reach as the older Zulu series of packs. As I get water from a hydration system, the side pockets are used for camera and GPS access (yup, I need a Peak shoulder strap camera storage system). The thumb loop on the holster pocket is much appreciated, making the right side pocket easy to use.

    Speaking of side pockets, frailty of side pocket material has been the only complaint I’ve seen on this pack from reviewers or owners. Perhaps the next version will use a more durable material for the side pockets. Mean while, Tenacious Tape will repair/protect any holes in the pocket mesh.

    Bill in Roswell, GA

  2. Michael,
    I’ve been very interested in the Optic since it came out. There are very few reviews of it and I was happy to see yours. We’re the same height, so it was interesting that you used the small size Optic (I have 17.5 in. spine length). Did you find the shoulder strap padding long enough on the small size? I wonder because Osprey’s are always too short in a size small.

    Normally I would try on a pack before purchase, but REI nor other outfitters carry the Optic in my area. REI doesn’t carry the Optic 55 online, which is the volume I would get as a year-round pack.

    Thanks and keep up the great work!
    Bill in Roswell, GA

    • Hi Bill, thanks for the good question. I know it can be hard to find a local store carrying the gear you want.

      Although I wouldn’t want the shoulder straps to be any shorter, the padding on the men’s small extends far enough for comfort on me (my chest is about 38 inches). As I wrote, I’m on the cusp between sizes, and the small works better for me–and is comfortable–because the medium is more likely too long in the torso for me. I also ordered the pack in small without trying it on, based on a recommendation from a contact at Gregory.

      The other consideration is to avoid overloading the pack or making it top-heavy, which can cause it to pull back more on the shoulder straps. You may already know this, but for the benefit of all readers, here’s my video on how to load a backpack:

      Good luck.