TOM BIHN Addax 31 Review

The TOM BIHN Addax 31 has a ton of room to pack gear inside, and its X-Pac fabric keeps it dry in rainy weather.

Our Verdict

7.9 /10
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  • Very roomy and expandable
  • X-Pac is very resilient to weather
  • Comfortable to carry thanks to harness system


  • Rolltop tends to unfurl over time
  • Feels a bit top-heavy
  • Hip belt’s large buckle rubs when it’s stowed

Technical Details

0 %

Carry-on Compliance

View 0/145 Airlines

31 %

Like the Look

Polled on Instagram

  • Capacity


    41 liters one roll | 48 liters no roll

  • Weight (lb)

    2.7 lb (1.2 kg)

  • Dimensions

    20.1 in x 12.8 in x 11.8 in (51.1 x 32.5 x 30 cm)

  • Notable Materials

    X-Pac, Packcloth, Ballistic Nylon, Ripstop Nylon, YKK Zippers, Woojin Hardware, Duraflex Hardware

  • Manufacturing Country

    United States

  • Laptop Compartment Size


  • Warranty Information

    Lifetime Guarantee

Full Review

X-Pac! You all know what it is, right? No, we’re not talking about the professional wrestler; we’re talking about the fabric. In case you aren’t familiar, the long and short explanation is that it’s a very water-resistant fabric made of multiple layers, born out of the same design philosophy that goes into sailcloth. Thus, it’s a solid foundation to build on if you want to make a bag that’s basically waterproof.

TOM BIHN Addax 31 Side
TOM BIHN Addax 31 | X-Pac and TOM BIHN together at last.

TOM BIHN! You all know who they are, right? No, not (just) Tom Bihn, the founder. TOM BIHN is the brand we know for high-quality bags and gear. One thing that mainly sticks out about TOM BIHN is the variety of fabrics and colorways for many of the bags they make. You can see where this is going, can’t you?

The Addax 31 is TOM BIHN’s first bag to use X-Pac, and we’re curious to see how the fabric affects its structure, comfort, and, yes, even the looks. We’ll also look at the usual aspects, such as compartment accessibility. This is a rolltop backpack, so it’ll be interesting to see how relatively thick X-Pac fares when you have to roll and unroll it.

External Components

Let’s dive a little further into X-Pac. As we’ve already mentioned, it’s a multiple-layer fabric, with the number and types of layers varying depending on which X-Pac variant it is. TOM BIHN specifies RX30 as the type of X-Pac they’re using, which is made up of three layers and is 100% recycled. As for the layers themselves, it’s a 300-denier recycled polyester face, recycled polyester X-PLY in the middle, and backed by another film of polyester.

TOM BIHN Addax 31 Brand
TOM BIHN Addax 31 | Don’t worry about the scuffs; it’s just dirt.

In case you were wondering, the X-PLY gives the fabric its distinct diamond pattern and that rugged feel. The looks can be somewhat polarizing, but the practical benefits of X-Pac are undeniable. To be clear, this doesn’t make the Addax 31 completely waterproof or submersible, as there are other ways water can get into the compartments.

Our sample has held up notably well, especially for a pre-production model. We’ve noticed a loose thread, which we can forgive. Other than that, though, we’ve only seen some scuffs at the front that are purely cosmetic and should wipe off easily with some elbow grease.

TOM BIHN Addax 31 Carabiner
TOM BIHN Addax 31 | There’s a place for your bike light here.

The X-Pac fabric TOM BIHN uses on the Addax 31 doesn’t feel particularly hard and crunchy. Compared to the other X-Pac-clad backpacks we’ve tested, the Addax 31 is somewhat softer and less aggressive in terms of structuredness.

There’s also ballistic nylon at the bottom to absorb some abrasion from setting the bag on rough surfaces. Plus, there’s a built-in loop where you can hang a bike light or other accessories if you want to. The loop is quite thick and well-built for that purpose, so we sometimes use it as a makeshift handle for pulling the Addax 31 out of the car.

TOM BIHN Addax 31 Water Bottle
TOM BIHN Addax 31 | Slimmer bottles also stay put relatively well here.

Flip the Addax 31 on its belly, and you’ll spot a serious-looking back panel. It’s covered in mesh and with a ribcage-like structure underneath. It’s a similar back panel to TOM BIHN’s Techonaut 30, a backpack we’ve lauded for its good carrying comfort. The back panel’s shape allows it to contour more easily while creating lots of open spaces where air can freely escape.

TOM BIHN Addax 31 Back Full
TOM BIHN Addax 31 | The rounded edges of the straps are easy on the shoulders.

The entire back panel also acts as the Addax 31’s luggage pass-through, by the way. It holds the pack vertically, which is optimal considering its top loader layout.

The Addax 31 is relatively big at 31 liters, and it can get even larger once you start playing around with expanding the rolltop. Thankfully, the shoulder straps do a good job cushioning the weight on the shoulders due to the soft foam blunting the edges. The sternum strap mounts on rails and slides up and down easily. Besides that, nothing adorns the shoulder straps like loops or branding.

TOM BIHN Addax 31 Luggage
TOM BIHN Addax 31 | Yep, the back panel also acts as a huge luggage pass-through.

The Addax 31 includes a removable hip belt, helping to relieve some of the pressure from the shoulder straps and shifting the weight higher and closer to you. We don’t think every user will find the hip belt necessary, and you may opt to leave it at home. Those of you who decide to keep it on can cinch it down so that it lies flat against the back panel, although you’ll still feel it rub.

Fit Notes

TOM BIHN Addax 31 Side By Side
Left: Lauren Maternowski, Height: 5’6” (168 cm), Torso: 16.5” (42 cm) | Right: Eric Hergenreder, Height: 6’0″ (183 cm), Torso: 18.5” (47 cm)

The Addax 31 carries over the largely comfortable carrying experience of the Techonaut 30, thanks to the shared back panel design. Where the Addax 31 falls short, however, is the weight balance. Once fully loaded, you can feel the top of the Addax 31 pull back away from the shoulder area. A pair of load lifters could be the missing link here, especially once you start utilizing the rolltop’s extra space.

TOM BIHN Addax 31 Strap
TOM BIHN Addax 31 | There’s some noticeable pullback around the top area, something load lifters could mitigate.

While the hip belt does its job in alleviating some of the Addax 31’s weight, its hardware is on the chunky side. It’s not a problem when you’re wearing the belt, but you can feel it once in a while when it’s cinched up against the back panel. Again, you can remove it, but that also adds prep time whenever you want to use it again.

Inside The Backpack

The Addax 31 is big enough to house more than one front pocket. In fact, it has two, one upper pocket and one lower pocket. The upper pocket contains the included key leash by default, but you can move it around since it’s attached to one of the many O-rings scattered around the Addax 31’s various compartments, which we’ll be mentioning as we take a look at each.

TOM BIHN Addax 31 Keys
TOM BIHN Addax 31 | There’s organization inside, but we mostly used it as a dump pocket.

The interior liner is yellow ripstop fabric, though it varies with the colorway. Fortunately, the X-Pac version of the Addax 31 gets this bright liner, and it’s a huge help whenever we have to dig out small accessories that can camouflage themselves in darker backgrounds (we’re looking at you, dongles that mostly come in black).

Apart from the key leash, you also get two mesh pockets here to organize your gear. In terms of space, this upper pocket doesn’t feel constrained, even when the main compartment’s packed out. As such, we can use this as a dump pocket that’s easy to reach into when we’re on the go. If you do run out of space, the lower pocket is just as roomy, although it lacks mesh pockets.

TOM BIHN Addax 31 Front Pocket
TOM BIHN Addax 31 | There’s more space in the lower pocket in case you need it.

You also get another zippered pocket on the left side of the Addax 31. You can technically use this as a bottle pocket if you want one that’s sealed away from the elements. However, we opt to use it as a flip-flop compartment. Low-profile sneakers may also fit, but bulkier footwear like boots are a no-go. Just keep in mind that since this pocket is built into the Addax 31’s body, it does cut into the space of the main compartment.

On the other side of the Addax 31 is the bottle pocket. It’s nothing special, just a standard mesh pocket that’s big and stretchable. A 40-ounce Hydro Flask fits easily inside and with sufficient grip that it won’t fly out if the pack’s tipped over. That grip gets less as you opt for slimmer bottles, though the 18-ounce Owala we typically use stayed put fairly securely as well.

TOM BIHN Addax 31 Fit Flops
TOM BIHN Addax 31 | Still run out of space? The left pocket’s got you covered.

The Addax 31 also has a separate laptop compartment that’s accessible through the right side of the back panel. Some prefer this sideways orientation for a laptop compartment, but not us. It makes access tricky when you have the backpack in front of you on the floor while sitting on a plane or a bus. Unless you have a generous amount of room around you, pulling a 16-inch MacBook Pro out sideways isn’t optimal compared to pulling it up. It’s a bit of a nitpick but worth pointing out for those who travel.

In terms of protection, the laptop compartment has padding both at the front and at the back. There’s technically no false bottom, but there is also padding there, so we won’t take any points away from the Addax. You may notice the reversed zipper track along the top of the inner mesh; that’s accessible from the main compartment.

TOM BIHN Addax 31 Laptop
TOM BIHN Addax 31 | We still prefer a top opening, but this is functional, too.

Thus we arrive at the main compartment with its signature rolltop. The first thing to note about the latter is that it slowly but surely unrolls over time. Fortunately, the buckles stop it from becoming totally undone, but it’s an odd quirk for a rolltop backpack.

We can chalk this up to two things: One is that this is another side effect of this sample being a pre-production unit. Two, the thickness of the X-Pac fabric makes it much harder to break in compared to other fabrics. Either way, we wish both buckles had some adjustment to help mitigate this problem.

TOM BIHN Addax 31 Strap Back
TOM BIHN Addax 31 | The rolltop slowly unrolls over time.

You’ll find more of the bright yellow liner inside the main compartment. We really appreciate this since other rolltops’ use of black liner gives us a hard time whenever we have to dig gear out. If you look closer, you’ll also find black piping at the base of the rolltop (the part where O-rings are dangling off), which serves as a helpful indicator as to where the standard baseline is for rolling the top.

There is plenty of available space inside. We’re able to fit several packing cubes and pouches stacked and side by side—enough gear to get us through a weekend trip for a bachelorette party, but not even close to fully saturating this rolltop’s maximum capacity. We still have the option of occupying the rolltop’s space, but we don’t need to.

TOM BIHN Addax 31 Empty Interior
TOM BIHN Addax 31 | A zippered port allows access to the laptop compartment as well.

While available space and expandability are a rolltop’s biggest strengths, the rolling and unrolling are the Addax 31’s weakness. Fortunately, its sheer size makes up for that with a large opening. Plus, its structuredness (part courtesy of the X-Pac) allows it to stand up and open, so looking into and putting gear inside is relatively pain-free, even with items stacked on top of each other.

As for gear organization, you get two mesh pockets on the front side that sit a few inches below the piping. They’re big enough for a laptop charger and a mouse, but you’ll have to use additional pouches if you have more than that. There are also four O-rings where you can hang even more accessories.

Last but not least is the zippered opening to access the laptop compartment. The opening may seem small based on pictures alone, but a 16-in MacBook Pro can pass through it. It may seem odd that TOM BIHN opted to have the compartment close with a zipper, but at least it allows you to seal it off. After all, you never know when something might spill in the main compartment.

TOM BIHN Addax 31 Stuffed
TOM BIHN Addax 31 | It just has so much space more than we need for an overnight celebration.

While we didn’t get to put the Addax 31 through an extreme wet weather event during testing, X-Pac is very much a welcome addition to the TOM BIHN lineup. It is a bit stiff for a rolltop opening, but we’d be happy to see it on their other packs, as well. As for the Addax 31 design, those seeking a very spacious backpack with room to spare (or grow into over time) are in for a treat.

Usage Timeline

Initial Usage

Condition: Excellent

  • Tall and skinny design seems roomy
  • Digging the organization across the whole pack
  • Interested to see how it does if the rolltop is pushed to its limit
2 Weeks of Use

Condition: Excellent

  • One loose thread, though we’re chalking it up to the fact that this is a pre-production model
  • Material is in great shape—only a few scuffs near the logo at the bottom
  • Rolltop wants to unroll even when rolled up and secured tight, though it never comes fully undone
  • Tons of space in here and really smart organization
By Lauren Maternowski
Created November 23, 2022 • Updated November 29, 2022
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