Rocky Mountain Underground Mountain Briefcase Review

Rocky Mountain Underground Mountain Briefcase Expandable BackpackReview Summary

Overall Rating: 9.3

This expandable travel backpack has a rugged, yet refined aesthetic that makes it look great in the city streets, airports, or out in the mountains. The profile is slim and the contrasting buckle and strap colors in both colorways add a bit of pop to the look.
The clamshell opening makes it an excellent travel backpack for nomads and travelers bouncing between destinations. Meanwhile, the carry features keep this expandable backpack comfortable to carry all across your travel destination.
This backpack is durably manufactured with rugged materials and a rigid construction to help it last a lifetime of adventures. It won’t double as a daypack at your destination or as a personal item on the flight, but you’ll be reaching for it every time you’re packing for a multi-day trip.

Pros & Cons

 Pros Cons
This backpack is both rugged and refined. Built to withstand the bumps and bruises of the road or trail, and look great while doing it. Although only 5 inches deep when unexpanded, the height and width of the bag are large compared to competitors and the bag can appear oversized on smaller framed people.
The clamshell opening and multiple interior zip components make this bag a pleasure to pack and use as your mobile chest of drawers while on trips. The backpack has only one external pocket for quick access items and no water bottle holder.
The padded shoulder straps and back panel make it a joy to carry, while the TPU coated external material keeps the bag fairly weatherproof and a snap to clean. There are a lot of built in features that might not be widely used like the 4 heavy duty compression buckles and stashable cargo net. All of these add-ons are cool but add extra weight and take up space.


RMU Mountain Briefcase

Who is the RMU Mountain Briefcase Expandable Travel Backpack For?

For travelers who like to jetset in style, comfort, and with plenty of packing space, the Rocky Mountain Underground Mountain Briefcase is the perfect travel backpack. The rugged exterior is tough enough to handle the bumps and bruises of the road, unexpected weather, drops, spills and more, all with a minimalist style that will turn heads.

This expandable travel backpack is right at home in planes, trains, taxis, Ubers, Airbnbs, hotels, and more. The Mountain Briefcase is amazing for road trips and flights, and is just as at home in city streets as in mountain towns. The clamshell opening and multiple interior dividers make living out of your pack while traveling a snap. This an ideal pack if you’re moving across multiple accommodations on your trip.

The RMU Mountain Briefcase is a travel backpack, but it can handle some short treks and overnight camping trips no problem. If you’re looking to do extended hiking on the trails though, there are better hiking backpack options with more carrying support and made with lighter materials.

At 35 liters this Rocky Mountain Underground backpack is also a less than ideal daypack for adventuring. It’s just a bit bigger than necessary and the lack of quick access pockets and water bottle holders prevent it from being an ideal daily exploration pack. That said, 35 liters of packing space expands to 50 so you can bring along your favorite daypack right inside of the RMU Mountain Briefcase backpack.

For digital nomads and professional travelers, the padded, floating laptop sleeve on the Mountain Briefcase makes this a suitable travel backpack when you’re working from the road.

RMU Mountain Briefcase Expandable Backpack

Shop the RMU Mountain Briefcase Expandable Backpack

Full Review of the RMU Mountain Briefcase Expandable Travel Backpack

Rocky Mountain Underground

RMU started with humble beginnings building skis for friends in their basement. Word got out about their high quality and innovative designs and before they knew it everyone was looking for RMU skis. RMU has grown into a reputable ski and snowboard manufacturer building exceptionally high quality and sustainable products. Their skis are still produced by hand with a low waste and high durability emphasis in every product.

This commitment to quality extends to Rocky Mountain Underground bags and gear. Every bag is uniquely designed to keep you moving and enjoying the outdoors. We love the exceptional quality and innovative designs that go into every RMU bag.

On the Outside of the RMU Mountain Briefcase Backpack

The RMU Mountain Briefcase Expandable Travel Backpack is a rugged and structured travel backpack weighing in at 4 lbs and 2 ozs unpacked and boasting 35 liters of packing capacity when unexpanded.

Rocky Mountain Underground Mountain Briefcase Backpack

This Rocky Mountain Underground bag is a slightly oversized 22” tall and 15” wide, but boasts a very slim 5” depth when unexpanded. This makes the backpack fit perfectly for adults roughly 5’ 8” and over, but can be a bit too tall and wide for travelers under this height.

RMU Mountain Brief Backpack

With a simple side zipper and loosening the compression straps, the backpack can expand in depth to 8”, adding an additional 15 liters of packing space. This brings the total packing capacity up to 50 liters.

On the front of the backpack there is a single quick access zipper pocket that is ideal for items like a phone and wallet. There are no other quick access pockets, and no water bottle holders on the exterior of the bag.

RMU Mountain Brief | Front Quick Access Pocket

The entire RMU Mountain Briefcase is wrapped in 630D TPU coated nylon on the exterior. This material is rugged, tightly spun and abrasion resistant. This makes sliding the pack in and out of the car or overhead storage on a flight no problem, and puts your mind at ease about nicks and picks in the fabric. The material is spill and weather resistant so getting caught in the rain or spilling a coffee on your bag isn’t the end of the world. Simply wipe it down with a damp paper towel. The weatherproof exterior is a great insurance policy, but the zippers and openings on the backpack are NOT waterproof, so we would not suggest pushing the limits in a downpour or near the water.

This TPU coated nylon exterior has a handsome look especially in the black colorway that we’ve been testing. The black color has a mostly matte finish (unlike other high gloss black backpacks that we’ve tested) and RMU has done a great job adding contrasting color with the bright zipper pulls, compression buckles and shoulder strap clips. The green canvas colorway features a polyurethane coating and black hardware, so you still get the contrasting colors without as much bright orange.

RMU Mountain Brief | Black Colorway

RMU has packed this bag with a number of features to make carrying it a pleasure.

The RMU Mountain Briefcase boasts a heavily padded back panel that doubles as a padded laptop sleeve.

RMU Mountain Brief | Back Panel

The backpack has a solid rigid construction even with an empty sleeve, but when utilizing the laptop sleeve, the backpack is even more rigid and easier to carry using any number of the heavy duty grab handles.

RMU Mountain Briefcase Backpack | Laptop Sleeve

Speaking of the grab handles, this backpack boasts grab handles on all four sides of the bag making it incredibly easy to pull out of the overhead compartment, or quickly drop it into a taxi. The shoulder straps even stow away into a hidden compartment behind the laptop sleeve. Simply unclip the straps from the bottom of the bag using the carabiner style clip, then pop open the button on the back panel above the laptop sleeve. Then stow the straps in the compartment for a clean and sleek briefcase pack that can more easily be maneuvered.

RMU Expandable Backpack | Grab Handles

When utilizing them, the shoulder straps on the backpack are simple and effective. Thick and heavily padded shoulder straps clip onto the top and bottom of the bag using carabiner style clips. These adjustable straps feature a mesh padding that makes them very comfortable and breathable. The wide straps provide a large contact area helping alleviate painful rubbing and pressure points when carrying, and the straps feature a contoured shape that allows for the most comfortable carry while keeping the straps out of your way.

Rocky Mountain Underground Expandable Backpack | Shoulder Straps

Adjustable compression straps on both sides of the bag keep the profile narrow and distribute the weight of the pack as close to the wearer as possible. The unique compression straps adjust using a standard buckle, but clasp together by slipping the smaller clip through the larger clip, locking them into place.

RMU Mountain Briefcase Expandable Backpack | Compression Straps

Speaking of, the hardware on the bag is a mix between modest zipper pulls, adjustment buckles, and clips, with a few oversized buckles like the compression buckles and shoulder strap clips. From a usability and durability standpoint, the mix of oversized and undersized hardware feels like a bit of a weakness, but aesthetically it all ties together well. To this point we’ve had no issues with durability, but are keeping our eyes peeled on these potential fail points.

Branding on the backpack is kept to a minimum with a small and subtle logo on the front of the backpack and few small tags with the RMU logo.

RMU Expandable Backpack | Logo

Inside the RMU Mountain Briefcase Backpack

A side zipper provides clamshell access to the primary compartment of the RMU Mountain Briefcase.

RMU Mountain Brief | Clamshell Opening

Inside the backpack, you’ll find a number of internal organization compartments lined and separated by a bright contrasting 150D polyester liner. In our black colorway this liner is a bright orange color making finding and stowing items a snap. The interior material is light, high contrast, and durable.

In the clamshell compartment that is part of the back panel, there is a large mesh pocket that can be used for dirty clothes or for a light jacket. Around the mesh pocket, a zipper opening reveals a large contained storage compartment perfect for several packing cubes, clothes, and a toiletry kit.

RMU Mountain Briefcase Review | Interior Compartment

In the clamshell compartment that is part of the front panel, there are two smaller mesh pockets that can easily fit things like an electronics organizer, a small pair of shoes or sandals, or a thin toiletry kit.

RMU Mountain Briefcase Backpack | Mesh Pockets

The zipper around these pockets reveals another large separate storage compartment where you can easily fit more packing cubes, a toiletry kit, or light jackets.

RMU Mountain Briefcase Backpack | Internal Compartment

The total packable space inside the RMU Mountain Brief is impressive for its size, but the organization within the bag makes finding and accessing your items easy. If you’re heading out on an overnight trip, there may be even more storage capacity than you need, but for weekend trips and longer, this backpack is a great option.

Overall the inside of this bag provides plenty of open packable spaces as well as organization.

Testing & Ownership

The RMU Mountain Briefcase has quickly become one of our favorite travel backpacks. This expandable travel backpack suitcase has all of the storage capacity needed for multi-day trips and is sleek and good looking. The mountain briefcase is an excellent alternative to a rolling suitcase as the thin profile keeps you mobile when darting through city streets or the airport and but still provides the packing capacity and clamshell opening of a suitcase.

RMU Mountain Briefcase Review

There is one downside to the clamshell opening and compression strap combination that we’ve seen before on another clamshell travel backpack (the Chrome Industries Summoner Backpack). If the compression straps are being utilized, access to the main compartment of the backpack is restricted. This requires you to unclip the compression straps every time you need something from the main compartment.

In the case of the RMU Mountain Brief though, we’ve found a partial solution by utilizing the mesh pockets on the interior of the clamshell compartments. Placing your light jacket, and electronics organizer in these mesh compartments means that you can pull them out as needed without completely opening the clamshell. Getting them back in though, is still a challenge.

RMU Mountain Briefcase Backpack Review

Alternatively, the clamshell opening is a huge benefit back in your hotel room or Airbnb, as you rarely have to fully unpack your travel bag. With the clamshell opening and separate storage compartments, living out of your backpack is a snap, especially when paired with some simple travel items like packing cubes, an electronics organizer and a toiletry bag.

The ideal scenario is to pair this expandable travel backpack with a carry-on daypack or sling bag. That way you can keep your quick access items in your carry-on and let the Mountain Briefcase do what it does best - getting your gear from one place to another and then acting as your mobile chest of drawers when you’re there.

The materials used and the rigid construction of the backpack does instill a lot of confidence in the durability of the backpack. There is some slight fading of the brand logo on the front of the pack after heavy use, but the material shows no sign of picking or punctures despite consistent use.

RMU Moutain Briefcase Testing

In months of testing the backpack shows very little external wear. Plus, RMU backs up this backpack with a lifetime warranty against manufacturer defects.

Final Verdict

The Rocky Mountain Underground Mountain Briefcase Expandable Travel Backpack is a top of the line travel backpack that’s a pleasure to carry. It’s slim, sleek and good looking, and has the space to get all of your gear from A to B. Once there, the clamshell opening and organization inside the backpack makes it easy to use the pack as your closet and allows you to move from accommodation to accommodation without unpacking and repacking your backpack.

The RMU Mountain Brief has been a joy to test and was awarded the best all around travel backpack of 2022!

If you love the style and quality of the Mountain Brief but want something purpose built for the trail consider the RMU Core Pack Adventure Backpack. If you’re looking for a daypack or sling bag to pair with your RMU Mountain Briefcase check out our collection of daypacks.

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