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ULA Catalyst Backpack Review

ULA Catalyst Backpack Review

ULA Catalyst Backpack



The Catalyst is a lightweight expedition sized backpack for carrying heavy or bulky loads. A favorite of backcountry guides, it can be used for many different types of trips from thru-hiking to winter mountaineering.

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The ULA Catalyst Backpack is the largest volume backpack in ULA’s line of ultralight style packs with over 75 liters of volume. Weighing 44 -48 ounces (depending on configuration), it’s a durable backpack that can carry an enormous amount gear and food, packed inside its main compartment or lashed to the exterior. I affectionately refer to it as the “moving van” of the ULA product line because it can carry so much. That said, the Catalyst is a great lightweight pack option for people who plan to take extended trips into the backcountry and need a pack that can carry a lot of extra food, cameras, or technical equipment in addition to your normal backpacking gear. It’s also an excellent pack for professional guides who need to bring extra equipment or carry their clients’ loads, when they need a little extra help.

Specs at a Glance

  • Total Volume: 4,600 cu in /about 75 liters
  • Rec’d Max Load: 40 lbs or less
  • Rec’d Base Weight: 20 lbs or less
  • Fabric: 210d Robic standard, or 500d Cordura available
  • Torso Lengths: 15″-24″
  • Hip Belt Sizing: 26″-42″
  • Gender: Men’s and Women’s-specific shoulder straps available.
  • See ULA’s Catalyst Product Page for Complete Specs

Main Compartment and Storage Capacity

The ULA Catalyst an ultralight style roll top backpack with a large main compartment, rear stretch mesh pocket, and large side water bottles pockets, with large zippered pockets on the hip belt. Several optional interior pockets come with the pack for storing a hydration reservoir (there are two hydration ports on the sides) or personal effects, but can be non-destructively removed with the plastic clips that hold them in place.

The Bottom of the Catalyst is curved rather than square in order to bring the heaviest items in close to your core where they can be carried most efficiently.
The Bottom of the Catalyst is curved rather than square in order to bring the heaviest items in close to your core where they can be carried most efficiently.

The main compartment is enormous with a long extension collar. It closes with a roll top, that’s clipped to webbing straps attached along the sides of the back panel below the shoulders. When the top is rolled close, the position of these webbing straps helps pull the load forward over your hips for maximum load transfer. There’s also a piece of webbing that runs over the roll top from between the shoulders to the top of the rear mesh pocket, providing additional top compression for keeping the load under control.

Rather than being square, the bottom of the pack rounds inward instead of having a square bottom in order to bring the heaviest items, typically placed at the bottom of your pack, as close to your lumbar back area where they can be carried most efficiently. Clever design.

The side water bottle pockets are solid, not mesh, to protect them from abrasion and tearing. They’re also quite large and you can fit 2 x 1 liter bottles in each side, easily reachable while wearing the backpack. Both water bottle pockets have drains at their base and are covered with solid 210d robic fabric for extra durability, including reinforced pocket bottoms. The top of each pocket has an elastic cord than can be cinched closed and secured with a cord lock to keep items from shifting or dropping out. If you habitually rip up mesh water bottle pockets, these should keep you out of trouble.

The front of each side pocket has a small hole you can stick you hand into although that’s not the intention; it’s part of the shoulder strap suspension system which terminates at the base of each pocket. But be forewarned, small items can fall out of the side water bottle pockets and shouldn’t be used for that type of storage.

Like many ultralight style packs, the Catalyst has a full length rear mesh pocket that’s ideal for storing wet gear or layers you want fast access to during the day without having to open up the pack’s main compartment. The mesh is very fine and heavy-duty so it won’t snag on protruding items or tear. I typically store my rain gear, water filter, and an empty wet reservoir in the mesh pocket when I hike, or a wet shelter, so I can pull it out easily to dry during rest stops and keep it away from my dry clothing inside the main compartment.

The Catalyst has a large rear mesh pocket good for storing wet or loose items you don't want to keep inside your pack. The outside of the pocket has a heavy duty criss-crossed elastic strap good for hanging wet gear or securing snowshoes to the back of your pack.
The Catalyst has a large rear mesh pocket good for storing wet or loose items you don’t want to keep inside your pack. The outside of the pocket has a heavy-duty crisscrossed elastic strap good for hanging wet gear or securing snowshoes to the back of your pack.

Finally, there are two large zippered pockets on the exterior of the hip belt, large enough to store a hat and gloves, a camera, snacks, Aqua Mira bottles, bug dope, and such. The fronts of both pockets are hard faced to prevent tearing with heavy-duty zippers for durability.

External Attachment and Compression System

The Catalyst has two primary mechanisms for compression, the roll top w/ top webbing strap for squishing your load down vertically, and a single tier of side compression straps for pulling gear in the main compartment closer to your back and core muscles. When fully loaded, carefully balancing the weight inside the pack and pulling the side compression straps tighter results in an easier carry. At 75L, the Catalyst has a larger capacity than most ultralight style packs and pack compression becomes more important for comfort and carry efficiency than on smaller volume packs.

In practice, I’ve also found it easy to store long items such as fishing rod tubes and umbrellas in the side water bottle pockets together with a water bottle, using the one compression strap to keep the longer items secured against the side of the pack. But the water bottle pockets are so large, you can store much bulkier items in them like a two person tent rolled up (held in place with the top compression strap), although I’d recommend balancing the weight on the other side of the pack with something that’s equivalent in weight.

The Catalyst as a long webbing strap the loops over the roll top to provide additional top compression
The Catalyst as a long webbing strap the loops over the roll top to provide additional top compression.

Having just one pair of side compression straps makes it a bit difficult to secure a pair of snowshoes to the sides of the backpack over the water bottle pockets (two straps are preferable). Snowshoes weigh 5 pounds per pair, making them one of the heaviest and most awkward items you might carry on a backpacking trip. While you can secure snowshoes under the elastic strap over the rear mesh pocket, there’s nothing stopping you from rigging up your own ad hoc side compression straps using cord and cordlocks between gear loops on the outside of the water bottle pocket and the perimeter of the rear mesh pocket. You just need to be a little creative.

One area where the Catalyst is very strong, is the ability to attach gear to its shoulder straps. This is great on wilderness trips where you want to keep electronic devices or map cases within easy reach. The front of the Catalyst’s shoulder straps have daisy chains attached to them, plastic gear loops, and four elastic water bottle holders (the latter are also easy to remove nondestructively.) Want to attach an umbrella to your shoulder straps? It’s quite easy with the rich set of shoulder strap attachment points provided on the ULA Catalyst backpack.

Backpack Frame and Suspension System

The frame, shoulder strap, and hip belt customization options on the Catalyst and ULA’s other packs are what sets their packs apart from most off-the-shelf backpacks you can buy at retail stores. In addition to 4 torso sizes ranging from 15″ to 24″ and 5 hip belt lengths ranging from 26″ to 42+”,  you can further refine the sizing and fit of the Catalyst  in several important ways to get an even more personalized fit.


The ULA Catalyst has a fairly beefy frame as ultralight style packs go, with two interior foam panels and two aluminum stays that terminate in the lumbar pad that holds the hip belt in place.

The Catalyst has two pre-bent aluminum stays that terminate in the packs lumbar pad. They're accessible inside the main compartment so you can shape them further if you need a more personalized fit.
The Catalyst has two pre-bent aluminum stays that terminate in the pack’s lumbar pad. They’re accessible inside the main compartment so you can shape them further if you need a more personalized fit.

The foam panels are used to keep angled objects from poking through the pack bag and int0 your back. The rear panel holds two pre-shaped aluminum stays (flat-sided metal rods) that terminate in the lumbar pad of the hip belt behind the small of your back. They do most of the work in transferring the load to your hips.

The aluminum stays are pre-shaped when you receive the pack and will work as-is for most people, but can be removed and bent further for a custom fit. You can’t do this with most off the shelf backpacks or don’t use a stay system. If you’ve never bent frame stays before, I recommend you contact ULA customer support for expert advice on how to go about doing it or undoing it, if you botch it up. Bending frame stays can significantly enhance the fit of a hip belt if you find that it slips constantly or give your head more clearance if it touches the top of your pack.

Hip belt

The hip belt is available in multiple lengths independent of the torso length of the backpack, making it possible to get a near custom fit. The hip belt is held in place with velcro on the front and back where it runs through the pack frame.

If you want to fine tune the torso length of your Catalyst, you can raise or lower the hip belt about 2″ by unsticking the velcro and moving it up or down, adjusting the torso length in the process. Reconnect the velcro – it holds solidly – providing yet another way to really dial in a personal fit with the ULA Catalyst. I never really appreciated this feature on ULA packs until I used it on the Catalyst. It made a big difference in load-to-hip transfer when I had to carry a lot of heavy gear and getting the right torso length was critical.

You can fine tine the torso length of the Catalyst by raising or lowering the location of the hip belt in the lumbar region where it connects to the frame
You can fine tine the torso length of the Catalyst by raising or lowering the location of the hip belt in the lumbar region where it connects to the frame

The Catalyst hip belt is quite wide and has two interlocking straps on each side that let you tension the top and bottom half of the belt to fit your precise body dimensions The top and bottom straps on the hip belt are actually one strap (if you make the top longer, the bottom gets shorter). I usually make the top strap tighter than the bottom, to prevent the hip belt from slipping down over my hip bones. But hip belt fit is a very personal thing that can be affected by your dimensions, how much body fat you have on your hips, and the curvature of your lower back. Experiment and contact ULA for fitting advice if you need it. They’re very responsive on fit issues.

The sides of the hip belt also have what are called hip control straps that pull base of the pack bag closer to your back and help dampen lateral sway when scrambling. This is important for a high-capacity backpack like the Catalyst to help reduce momentum that can make you lose your step and tumble when carrying a heavy load.

Both the hip belt, back panel, and shoulder straps are covered in padded spacer mesh which is cushy without being too soft. The holes in the spacer mesh have a tendency to collect debris like spruce or pine needles however, if you wander off-trail.

Shoulder Straps

The Catalysts shoulder straps are available in too styles, J-shaped or S-shaped, to accommodate people with breasts or barrel chests. Ladies, S-curved shoulder straps are better than the so-called “unisex” shoulder straps provided by other pack makers. ULA is one of the few lightweight pack makers that provides features and sizing that are tuned for a female fit, something to seriously consider if you plan to wear a backpack for the six months at a time, especially if you need to haul more gear in a pack that’s the size of the Catalyst.

In addition to the numerous attachment points (discussed above) the shoulder straps have front load lifter adjustments, which slide down the front of the shoulder pad to let you adjust the angle of your load lifters if they’re too flat (a 45 degree angle is ideal). Most of these shoulder pad options are usually only found on high-end expedition or custom packs costing much more than the Catalyst.

The ULA Catalyst is a great backpack for gnarly trips above treeline - shown here climbing Mt Washington in New Hampshire's White Mountains
The ULA Catalyst is a great backpack for gnarly trips above treeline – shown here climbing Mt Washington in New Hampshire’s White Mountains.


The ULA Catalyst is one of the largest sub-three pound ultralight style backpacks that you can buy with 75 Liters of carrying capacity. It’s ideal for more experienced backpackers who need a high-capacity backpack to carry a lot of extra gear or supplies into the backcountry, but want a minimalist style backpack that’s all function with little extraneous fluff. Like ULA’s other packs, the Catalyst is available with a wide variety torso lengths and hip belt sizes, so you can get a great fit, with additional capabilities that let you tune the fit to your personal dimensions – really an essential when carrying heavier loads. The Catalyst is also a durable and proven pack for tough trips, one that’s earned near legendary status among guides and backcountry adventurers.

While the Catalyst can be used by backpackers transitioning from more traditional gear and a heavy pack to a lighter one, I would encourage you to look at the 68 liter ULA Circuit backpack if most of your trips are going to be four days or less. The Catalyst is a high-capacity backpack that is really best used for larger loads and longer trips.  While the two packs are very similar and can even be difficult to tell apart for the untrained eye, the Circuit is a better sized pack to get if you intend to further reduce your load and gear volume over time. For more information about the ULA Circuit, read my review.

See also:

ULA Equipment-Free Shipping on all US Orders

Disclosure: ULA loaned the author a Catalyst backpack for this review. 

Editor's note: Help support this site by making your next gear purchase through one of the links above. Click a link, buy what you need, and the seller will contribute a portion of the purchase price to support SectionHiker's unsponsored gear reviews, articles, and hiking guides.

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  1. I’m torn between this and the Seek Outside Divide for my cold weather pack. Was hoping for a bit of versatility as my loads vary pretty drastically depending on if I’m bringing the dog or not. He’s less able to carry his own stuff as he ages. How do you feel the packs perform with less bulky loads compared to eachother?

    • The Catalyst is a bit better but Neither are great with a load that doesn’t fill up the capacity even if you pack your sleeping bag loose. They really are high volume packs.

  2. The Catalyst is the most comfortable pack I have used in recent years. Took it on 3 TGO Challenge two week backpacks across Scotland and loved it.

    It has one weak point. It lets in an awful lot of water in wet conditions and I now take a lightweight outer cover with me to reduce this.

  3. I have been using the Catalyst for any hikes over 4 days the past two years and have found it comfortable even when having to lug 35+ pounds (food and water included) several times. My last hike I used an Wild Ideas Bearikade (Weekender) and the pack held it horizontally without any problem. I have also experienced a smaller item poking out the hole in the side pockets as mentioned, but before anything was lost I made sure to put those somewhere else. Also to note, due to the amount of use of this pack, I have had to wash it a couple of times and it was very easy to remove to remove/re-insert the stays and back panel (washing was done in a front loader washing machine). Overall I have been very happy with the pack for longer trips and where I want to minimize my resupplies.

  4. I’ve used my Catalyst for several years now, and I just can’t say enough good things about it. I use it on ALL my overnight trips regardless of duration. I recently pitched all my compression sacks, and I just stuff everything: sleeping bag & pad, tent, clothing right into the pack. It takes up more space, but there’s no more pissing around rolling things up and compressing them (YAY…!!!) in the mornings when I break camp. People look at me like I’m crazy for carrying such a big bag on one-nighters, but it only looks big. I generally carry 24-34 lbs including food and water (sometimes 10 lbs of that weight is just water). In the SW we often carry more water than those living in wetter areas. You really don’t want to run out of water here, and water holes are often unreliable or disgustingly stagnant.

  5. I really like the features of this pack! I have a petite frame and 5’2″. Looking for lightweight and was interested in the rounded base aspect (“to keep heavy items close to my core”). On a long backpacking excursion, I carry my max % weight at just under 30#.
    Loaded, how’s the low back fit- curvy? flat? stiff?
    Recommendations for dealers to try one?

    Any input on this pack from smaller women would be especially appreciated.

  6. I’m taking a crew to Philmont next summer and it looks like I’ll need a larger pack to meet their requirements. From what I read they are the exact opposite of ultralight.

    Should I be considering something other than this pack?

    • I know many people who’ve gotten away with lighter weight gear at Philmont. I suggest you seek them out. The 75L catalyst is a big pack. I’d take the 60: ULA Circuit if you could get away with a smaller volume one, but the Catalyst is a moving van and very good if that’s what you need for a troop. You might also look at the Seek Outside Divide if you decided you need to carry heavy gear, as it is an external frame pack.

      • I owned a 2016 Seek Outside 4800 series pack. It is a nice design but the pack needs further development. The straps don’t work well and it flopped all over on me. I’ve owned a lot of packs and am used to adjusting them so it wasn’t a fit problem. After 50 miles I called Granite Gear from the trail and had them drop ship me a new pack. The Granite Gear pack is great but the ULA weighs less so I plan to change. Try to get your hands on a Seek Outside pack before purchasing one. The Seek Outside pack could be a great product, but the company seems reluctant to make changes. They are a small company that caters to hunters. They are not concerned about long distance hikers.

  7. I currently use a Granite Gear Crown VC 60, older model, and it has worked for all of my trips this far, up to 6 days. But, my husband usually carries the bear barrel. When I add the Bearikade Weekender it pretty much fills the pack, and I also feel it through the back panel. Since I’m planning to do some more extensive trips on my own, I’m considering either the Catalyst or the Circuit. I wouldn’t bring any more clothing or other gear, just needing to add that bear barrel. Would you recommend the Circuit or the Catalyst?

    • I guess I should say, I won’t carry more than 35 pounds, ever. My base weight is between 12-15 pounds, depending on weather. My food requirements are only about 1.2-1.5 pounds a day, max. I have gotten close to 30 when I’ve needed to carry more water for dry camping. Normally I would carry an Ursack when needed, but in some places a bear canister is essential. So that’s my real need for a bigger pack than the GG VC60.

      • Actually, I’d recommend the new Granite Gear Blaze 60. You can tuck a bear canister under the optional top lid or lash it to the top of the pack over the roll top closure. It also has an adjustable gender specific hip belt, shoulder straps, and an adjustable torso.

        But if you want to stick with with a ULA, you will have to put the canister inside, and you’ll probably want to use a Catalyst for that.

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