ULA Catalyst: The Ultimate Review (I Used this Backpack for 10+ years)

In the spring of 2015, I backpacked 400 miles through the Grand Canyon over the course of 36 days.

The trip called for more planning than a traditional thru-hike, because there was no opportunity for resupply.

Zilch, zero, none.

I placed 5 food caches to see me through the trip.

I was solo. A major gear failure would not only end the trip, but require an exhaustive evacuation.

The ULA Equipment Catalyst is the backpack I chose.

See more about my 10+ years of experience with this pack at the end of the article.

Overview: Where does The Catalyst fit a need?

The Catalyst may be the best pack for carrying 40+ pounds for the long haul.

There’s other, more durable packs for carrying heavy loads, but none can do so at under 3 pounds while maintaining such a reasonable level of comfort.

Therefore, the Catalyst is best for a weight conscious (or even ultralight) backpacker that has a need to carry more stuff. Sometimes there’s a need for climbing gear, glamping supplies, extra food, extra beer, and so on. This is the realm in which the Catalyst shines.

As a perfect example, professional backpacking guides tend to like the Catalyst for their work trips.

Seasoned backpackers often find it as a bridge in the journey to cut some weight. Rather than getting an even smaller and lighter pack (like the ULA Circuit or Hyperlite Southwest 3400), you may find some comfort in the additional volume found in the Catalyst – 75 liters, to be exact.

Specs & Features

The ULA Equipment Website lists the following specifications.

WEIGHT: Precisely 47.6 ounces (just 0.4oz under 3 pounds) or 1,324 grams. This weight is specifically for those with a medium torso size and the medium hip belt. I am 6’0 and I wear the medium torso and small hip belt.

MAXIMUM LOAD: The recommended maximum load published by ULA is “40 pounds or less.” Most hikers like myself find this to be somewhat conservative, comfortably carrying 45 or even up to 50 pounds. Note that hauling heavier weights shortens the lifespan of the pack, hence the conservative rating.

VOLUME: 75 liters, or 4,600 cubic inches. The volume breaks down as follows, in cubic inches:

• Main Body: 2,600
• Front Mesh Pocket: 600
• Left Side Mesh Pocket: 350
• Right Side Mesh Pocket: 350
• Exterior Collar: 600
• Left Hipbelt Pocket: 100
• Right Hipbelt Pocket: 100

MATERIAL: The majority of the pack’s material is called ULA 400 Robic fabric. It’s about as durable as can be in this weight class and water resistant, but not waterproof.

Can I get mine in Red?

In April of 2021 the fabric is offered in a choice of 6 colors. These are blue, purple, red, teal, black, and original green. If the color you want is out of stock, they will make your pack “to order” for a $15 dollar fee, which provides a nice opportunity for dialing in all of your customizations.

Does a bear canister fit in the ULA Catalyst?

Absolutely. The BV500 fits my medium Catalyst horizontally as well as vertically, though I find the horizontal fit to be a bit snug and cumbersome for the daily grind of the trail. ULA states that every bear canister on the market will fit the Catalyst horizontally, with the exception of the Bearikade.

If you’re packing a bear can horizontally, remember it’s best not place it at the absolute bottom of the pack.

J-Strap vs S-Strap

When going through checkout on the ULA website, you’ll see an option to select “J Straps” or “S Straps.” I always opted for the traditional J-shaped straps. They always felt comfortable enough, but after reviewing the details I begin to wonder if the S-shaped straps would work even better for me.

I’d always assumed that the J Straps are best for men and the S straps are best for women. This is mostly true, but now I see that the official ULA statement says:

men with athletic builds, i.e. strong, square shoulders will find the S straps work better. Swimmers, climbers, weight lifters, surfers, triathletes, XC skiers, etc usually prefer the S straps.

Is ULA trying to tell me that I need to hit the gym?

Don’t hesitate to send them an email or give them a call to help determine the best style for you.

Availability

It’s rare for an outfitter to carry the ULA Equipment brand, so must of us will be ordering the pack without the opportunity to try it on. REI, for example, does not offer the ULA Catalyst for sale.

ULA Equipment can be found, though, at a handful of home-grown outfitters. You can check the ULA website for the complete list of retailers. I think it’s no coincidence that most of the outfitters happen to be in trail towns along the Appalachian Trail and PCT.

You can also find used versions for sale on websites like Geartrade.com.

Sizing & Fit

The ULA website has very specific and reliable instructions for dialing in your personal size, so don’t be afraid to order online – it’s how I’ve always bought their packs.

You’ll want to have a measuring tape on hand, and a friend to measure your torso via the length of your spine. Torso length and body height will determine the overall size of your pack, and your normal waist size will determine your hip belt size.

Please take the time to go over the detailed instructions on the website, and again, you’re encouraged to contact peter@ula-equipment.com with questions.

The Frame

The frame of the backpack consists of 2 vertical aluminum stays that run down the height of pack. Each is held in a fabric enclosure that connects it to a thin, hard foam pad that acts as the pack’s skeleton. This is buffeted by a thicker, softer foam pad that rests against your back.

The metal stays start at about 8 inches apart at the top of the pack, but taper inward so at the bottom of the pack they’re just 3 inches apart. If you own a ULA Catalyst for long enough and properly use and abuse it, the stays will eventually begin to show through the bottom of the pack (see below).

All of these elements are accessible for you to examine via a zippered compartment (pictured above). It’s possible to bend the stays to help align the frame to the curvature of your back. Personally I tend to leave it alone, so over time the frame will get “broken in” to my body’s ergonomics and typical load.

Storage Functions

If you came here from my Ultimate Gear List, you’ll know that I’m big fan of breaking down backpacking gear to its primary function or purpose.

A backpack of course, simply carries things. So let’s look at where the Catalyst carries things.

The Main Compartment (It’s not Waterproof)

With a volume of 2,600 cubic inches, the main compartment is the meat and potatoes of the pack. It’s a simple space that’s only accessible through the top – you won’t find a silly sleeping bag compartment in a ULA. The sides are composed of the 400 Robic fabric, and the front (under the outer mesh pocket) is made of a softer ripstop nylon. The bottom is reinforced with a heavier material.

The top of the compartment is designed with a roll-top closure, similar to those found on waterproof dry bags. Buckles on each end of the roll top can be fastened via straps that connect to the side of the frame.

There’s also a single buckle that fastens over the top. It’s ideal for fastening light but bulky items, like a foam sleeping pad. I personally never took the time to fasten the roll-top closure. I’d simply fold the closure over itself and fasten it shut with the single, over the top strap. My foam sleeping pad was secured under this strap and kept everything in its place.

This would leave the straps for the ends of the roll top closure dangling uselessly, so I eventually cut these straps off. Proceed here with caution – it’s best to spend a lot of time with your Catalyst before you go chopping away any of its bits and pieces.

X-PAC Fabric vs. Robic?

Note that the Catalyst is NOT waterproof, and that it’s best to carry a waterproof pack cover (ULA makes some of the best).

When you opt to customize your pack, you’ll notice that there’s a choice to be made among numerous customizable fabrics and something called X-PAC, which claims to be similar to cuben fiber (aka Dyneema Composite).

I personally have not seen a ULA with anything but the stock 400 Robic, and do not recommend straying from it. Don’t just take my word for it though, here’s what someone said in a Reddit thread:

I had an email exchange with the owner Chris on this topic. He has found the Robic fabric they use to be the toughest for the weight and he did not recommend the lighter weight Xpac fabrics.

Otherwise, enjoy your further explorations down the rabbit hole of fabrics and limitless options.

Water Bladder Compatibility

The main compartment has two openings for threading your water bladder hose. These are located at the top of the frame on both sides of the pack. ULA used to include a sleeve for your bladder as an included component. It was found that a majority of lightweight backpackers were removing the sleeve as a means to save weight, so now this feature is only available as an accessory.

When backpacking with the Catalyst, I almost always used a Camelbak 3L bladder. I’d often carry 2 of these bladders for more serious water needs on my desert hikes in the Southwest. In all these miles I never found myself particularly wanting of a sleeve for them.

The Hip Belt

The hip belt is connected to the bottom of the frame with a thick strip of velcro and a single strap on each side. In practice this setup is more sturdy than it sounds, and allows for swapping belts if your size should change. For example, you may start a thru-hike of the PCT with a size Medium, but discover after a few months that you’d now prefer a size Small. No problem, you can easily swap the belts.

Hip Pockets

The dimensions of the hip pockets are approximately 6.5 x 4.5 x 2 inches, each with a published volume of 100 cubic inches. A pocket will perfectly fit my iPhone XS with a Lifeproof case. They are made of a very durable material that I’ve put through the off-trail wringer, thrashing through thorns. The zippers have never failed me (Take note here, Big Agnes Tents!).

Side Pockets

The early versions of the Catalyst used a simple mesh material for their side pockets, but they soon switched to a more robust material after hikers shredded them all too easily. Today I still find the side pockets to be the first part of the Catalyst to fail. I feel that this is primarily due to their exposed location, especially when they’re loaded with water bottles whilst tearing through thorns or against solid rock.

Each pocket has a volume of 350 cubic inches – plenty of room for 2 Smartwater bottles (1 liter each) or a single Nalgene. Each side of the pack has a single compression strap above the pocket, perfect for securing long thin items like tent poles.

The lip of each pocket has a yellow shock cord (similar to those found on the shoulder straps) to hold items in place. The cords are reachable while you’re wearing the pack, and operable with one hand. I’d rarely take the time adjust these.

ULA claims that water bottles in the side pockets are accessible while wearing the pack. This may be true for some folks, but I find it to be impractical, especially when it comes time to replace the bottle.

Front Pocket & Compression Cord

The front compartment of the Catalyst has a substantial volume of 600 cubic inches. It used to be a genuine mesh, but now it’s made of solid, more sturdy material. I like to keep my daily needs here – like snacks throughout the day, maps, and so on.

Over the top of the mesh pocket there’s a long, cross-threaded compression cord. Some hikers that carry a foam sleeping pad like to store it here, held in by the cord. For the majority of thru-hikes that I did with the Catalyst, I carried a bulky fleece hoodie that I liked to store with the cord. This way it didn’t occupy the interior space, and was easily accessible for temperature changes throughout the day.

Off-trail hikers will discover that the compression cord occasionally gets snagged on tree branches. Such is life. Some folks never use the cord, and choose to permanently remove it.

There’s a set of ice axe loops below the front mesh.

The J Straps

The J-strap shoulder straps are a simple design, weaved into a thick seam at the top of the back pad. It’s always prudent to avoid lifting a loaded pack by a single shoulder strap, but I’ve never had one fail as result of this (or heard of such a failure in the Catalyst). This may be due to my good practices, or good design – likely a combination of both.

The shoulder straps are tightened at the bottom (no surprises here) and also include the “load lifting” adjustment at the peak of the straps. The idea is that you can tighten these to bring the load snug to your upper back for uphill hiking, and then loosen them to curb the pressure on descents. Personally I’d always end up leaving this adjustment in its tightest position at all times.

Each strap used to have 2 small shock cords. These are intended as water bottle loops, and provide a snug fit for a Smartwater bottle, but I’ve never used them for this purpose. I also must say I’m not partial to the ugly yellow color they use for the shock cords. They’re now only available as an accessory.

Likewise ULA used to include hand loops on the straps. Those that don’t use hiking poles find them convenient as a grip to avoid the pooling of blood in their hands. Nowadays ULA only lists these as an accessory too.

A basic sternum strap is also included. Some brands utilize the plastic buckle in the sternum strap to include a built-in emergency whistle (which I always thought was pretty neat) but ULA doesn’t include this feature.

I have never tried the S Straps.

The Back Pad

The rear side of the hip belts, shoulder straps, and back pad are made of the same perforated material. It holds up great, and combined with the soft foam underneath, it’s wonderful for ventilation and lifting sweat from your back. In this realm ULA is not quite as advanced as Osprey’s system, but it’s certainly more comfortable than the suffocating material found on Hyperlite’s packs.

If you go off-trail a lot (or even if you don’t) the design of the back pad has a tendency to collect small twigs and thorns that will embed themselves there, persistently stabbing your back. Granted this is a minor annoyance, but you may find it worthy of consideration.

Add-Ons

ULA offers a handful of accessories. These include the aforementioned water bladder sleeve, hand loops, and an internal zippered pouch for securing important items, like a wallet or keys.

These used to be standard items, but a majority of hikers were removing them to save some weight. Likely after noting the popularity of Andrew Skurka’s article about how to do so, ULA wisened up and changed these features to add-ons. He did the company a favor by spelling out exactly how to reduce the published weight for their product.

My Experience with the ULA Catalyst

The purchase of my first ULA Catalyst in 2008 marked the beginning of my transition from being a heavy backpacker to going lightweight, and even ultralight. My previous pack (a Gregory Shasta, purchased in the summer of 2000) weighed 8 pounds empty, so my switch to the Catalyst gave me an immediate savings of 5 pounds from my base weight.

2008 was also when I first moved to the South Rim of the Grand Canyon, and all of my ensuing, most notable hikes in Grand Canyon (over 4,000 miles) were accomplished with the Catalyst. I additionally carried the pack on thru-hikes of the JMT and Colorado Trail, as well as a long section of the Hayduke Trail in Utah.

As mentioned at the beginning of the article, I replaced my original Catalyst with a new version in 2015 for a 400-mile Grand Canyon hike without resupply, where a gear failure would have meant the end of the trip.

Rather than sending my old backpack to ULA in an attempt to receive a free replacement, I bought a new one at retail price. I thought the 6 years of abuse that I gave it didn’t warrant getting a new one for free (Though in hindsight I guess it was worth a try). So in this regard I can’t speak for the customer service in the ULA returns department.

Using the Catalyst as a Carry-On

I’ve used the ULA Catalyst both as a carry-on and as a piece of checked luggage for airline travel. Before using it as a checked bag, I was sure to fasten all the buckles and take some time to ensure that all of the loose straps were neatly wound amongst themselves and tied.

The one time I used the Catalyst as a carry-on was in 2012 when I traveled to Peru to backpack the Inca Trail to Machu Picchu. I was flying solo and changed planes about a millions times (Phoenix to Houston to Mexico City to San Salvador to Bogota to Lima to Cusco, for the curious) so rather than dealing with checking bags, I managed to fit everything I needed in the Catalyst as a carry-on.

Granted this was almost a decade ago, but I did not have any problems with its size and bulk as a carry-on. Here’s the dimensions of the Catalyst, as I’ve personally measured them:

Dimensions

These are the dimension for a Medium torso size – other sizes may vary.

Height: 24 inches (2 feet)

Width: 14-15 inches, nothing in side pockets

Thickness: 10 inches (back pad to front, fully packed, nothing in mesh pocket)

The hip belt pockets are about 6.5 x 4.5, with a thickness of about 2 (inches)

Let me know in the comments if you’re interested in any more specific dimensions.

Wear & Tear: the 3 Hot Spots

The 3 places I found the Catalyst most likely to begin breaking down are as follows.

First, I’ve already mentioned the shredding of the side pockets, but I believe this is somewhat inevitable given the punishment of thorns that I’d put them through.

Second, the plastic buckles can easily break – particularly the one found on the strap that cinches over the top of the pack. In both versions of my Catalyst, over time I’d find that at least one of the 2 teeth would snap off the male part of the buckle.

This could be a result of the way I’d cinch it tight to hold my sleeping pad in place, combined with prolonged sun exposure in the arid Southwest. To fix the problem in the field or at home, I’d just remove one of the yellow side buckles (intended for securing the ends of the roll-top) and replace the top buckle with one of those, since I didn’t use them anyway.

Third, over time the aluminum frame stays can wear through the bottom of the pack. Eventually (again, in both my Catalysts) this would develop to the extent where one of the aluminum rods would descend and begin poking a few inches through the bottom of the pack. At least once or twice a day I’d reach behind me as I was hiking, and shove the stay back up into the pack. That worked okay, so this failure isn’t the end of the world, but it was a sure signal to replace the backpack soon.

I think this is the result of scraping the bottom of the pack on rocks, and loading the pack with too much weight.

Summary – Is it for you?

In 2019 I went on a shopping spree prior to a hike on the Arizona Trail and overhauled all of my gear. For years I’d been considering downsizing from the volume of the Catalyst for something smaller to save weight, so I ultimately replaced it with the Hyperlite Southwest 3400.

For most weight-conscious thru-hikers, the Catalyst is a mule and simply more backpack than is needed. With that said, the Catalyst is perfect for serious hikers with a need to carry more stuff, like a few extra beers to a base camp, a giant first-aid kit for backpacking guides, a packraft, and so on.

If you’re considering a thru-hike of the PCT or another long trail, I think you’re better off with a smaller pack. In particular, my 3 favorite packs for thru-hikers are as follows:

• the ULA Circuit
• the Hyperlite Southwest 3400
• the Gossamer Gear Mariposa

I’ll end the article with a few statistical comparisons to other backpacks. I hope you found this review to be useful, and let me know what you think of the ULA Catalyst in the comments!

Vs. the ULA Circuit

Weight: The Circuit is 10 ounces lighter.

Volume: The Catalyst has more volume, +400 cubic inches

Max Load: The recommended max for the Catalyst is 40lbs, whereas the Circuit is 35lbs.

Horizontal Bear Can: Not possible in the Circuit

Features: The Catalyst and Circuit basically have all the same features. The Circuit is just a slimmer build, with a single aluminum stay as opposed to 2 in the Catalyst.

Vs. the Zpacks Arc Haul

Weight: The Arc Haul is 24 ounces lighter than the Catalyst.

Volume: The Arc Haul carries 13 liters (820 cubic inches) less than the Catalyst.

Max Load: The maximum recommended load for both packs is 40lbs, though most hikers agree that ULA’s assertion is conservative, whereas Zpacks’s is pushing an upper limit.

Horizontal Bear Can: The Arc Haul will not fit a horizontal bear can.

Features: The Arc Haul has a true outer mesh pocket, ideal for drying wet items throughout the day (the Catalyst does not). The Arc Haul does not have hip belt pockets.

Vs. the Osprey Atmos AG 65

Weight: The Osprey Atmos is 23 ounces heavier than the Catalyst (about a pound and a half).

Volume: The Catalyst has 10 more liters of volume than the Atmos (roughly 600 cubic inches).

Max Load: Osprey publishes the max load for the Atmos at 50 pounds – 10 more than the Catalyst.

Horizontal Bear Can: Yes, the Atmos 65 fits a horizontal bear can.

Features: The Osprey Atmos is the widely regarded as the best all-round pack on the market. It comes with a strong suite of bells and whistles – a removable lid, zippered outer pockets, a sleeping bag compartment, buckled straps for additional gear, etc. Osprey also stands apart for its awesome back ventilation and lifetime warranty. Unfortunately you’ll pay the price for all this with some additional weight.

Vs. the Gossamer Gear Mariposa 60

Weight: The Mariposa is 16 ounces (one pound) lighter than the Catalyst.

Volume: The Catalyst holds 15 more liters than the Mariposa, or 915 cubic inches.

Max Load: The maximum recommended load for the Mariposa is 35 pounds, 5 pounds less than the Catalyst.

Horizontal Bear Can: Some small bear cans will fit horizontally, but most (like the BV500) will not.

Features: The Mariposa is a favorite pack among thru-hikers. It’s features and durability are second to none in its weight class, as the Mariposa includes a convenient over-the-top closure, an extra side pocket, durable Robic fabric, and more.