Ultimate Direction Fastpack 20 Review

Ultimate Direction Fastpack 20 Review

Put a minimalist spin on the classic overnight pack, and you get Ultimate Direction’s Fastpack 20, built to carry all the fluid, food, and gear you need to spend a full day (or more) on the trail.

Ultimate Direction Fastpack 20 Features:

  • Cargo capacity: 15-23L / 915-1403 cubic inches
  • Weight: 1 lb 3 oz / 535g
  • Dimensions: 20″ x 11.75″ x 9.5″ / 51 cm x 30 cm x 24 cm
  • Infiknit harness: continuous, seamless back panel and shoulder strap system
  • Main roll-top compartment expands from 15L to 23L
  • Large capacity rear stretch-mesh pocket
  • Side vertical zipper pocket with key clasp
  • Low-profile daisy chain system for multiple attachment points
  • Bilateral hiking pole / ice axe loops
  • Two large flat front pockets are also water bottle compatible
  • Two small front pockets and stash pocket
  • Side mesh pockets
  • Dual adjustable sternum straps
  • Integrated side compression Z-straps for varying load capacities
  • Removable foam back panel for comfort
  • 2 size options
  • MSRP $150

Ultimate Direction Fastpack  20 Hydration Pack Review

Fastpack 20, Meet the Tetons

Ultimate Direction did a lot of advance testing with this pack prior to the release date, providing test samples to numerous elite athletes and gear reviewers alike.  The idea was for us to give the packs the most thorough and challenging testing we could think of – and from the outset, the company was confident that the Fastpack 20 would be up to the task.

Their confidence was well founded, at least from the experience of our testers.  We tested the Fastpack 20 for a week in the Grand Tetons, two days on Mt Shasta (including a summit trip), three days in Yosemite, and about a dozen trips through Big Sur and the Ventana Wilderness of central California.  The Fastpack 20 has proven to be a remarkable pack, equal parts functional and versatile and durable; for day-long mountain adventures, it deserves to be on your short list of top contenders.

Ultimate direction fastpack 20 shasta

Scrambling towards Mt Shasta summit

One of the few drawbacks to the pack is that unlike most Ultimate Direction gear, this isn’t specifically a hydration product, in that it does not come with either bottles or a hydration reservoir.  However, the pack is reservoir compatible with an internal reservoir sleeve, Velcro fastening loop, and a central access opening for drink tubes.  Our testing was done primarily with a 100-oz Hydrapak reservoir in the internal sleeve.  There are also plenty of places to stash bottles of various sizes, but these have to be obtained separately.

Carry Lots of Stuff — Just Don’t Go Sprinting Off

Even with a full reservoir, storage capacity of the Fastpack 20 is impressive.  Ultimate Direction says it’s able to accommodate up to 23L of cargo, but this seems like a low estimate given the large stretch mesh pocket on the outside.  You could easily load this pack with up to 20 pounds of gear, but its functionality changes a bit based on how heavily it’s loaded, as we’ll explain shortly.  First, let’s take a tour of the pack.

UD fastpack 20 main compartment

Main compartment with hydration sleeve and attachment loop inside

The main compartment is a cavernous cylinder that occupies the entire height and width of the pack, with a dry pack-style roll top closure to cinch down loads that don’t occupy the full capacity.  You can fit an ultralight sleeping bag and pad in here if an overnight trip is on the agenda, or a ton of just-in-case supplies for a day hike.  The roll top clips fasten to side straps that zigzag down the side of the pack, so that when you cinch the straps, the entire pack is compressed.  There is a water resistant finish on the Fastpack, but contents of the main compartment will see moisture if exposed to steady rain.

UD fastpack 20 rolltop

Rolltop closure with side buckles; large external mesh pocket

External to the main compartment is a stretch mesh pocket that also runs the entire height of the pack for on again / off again items like jackets or rain gear.  The mesh has quite a bit of stretch to accommodate a hefty volume of items, but stays firm and doesn’t allow things to bounce out.  This pocket is the primary rationale for how the cargo capacity can extend well beyond 20L.

UDfastpack 20 side pockets

Wide stash pockets on sides; vertical zipper pocket with key clip at top R.

Adjacent to the main compartment on either side are wide (approx. 6” across) mesh pockets made of the same stretchy mesh material on top of the main compartment.  These pockets can easily hold small items like hats, gloves, or maps.  They aren’t quite deep enough on their own to secure a water bottle, but in combination with the zigzag straps, a bottle can easily be contained here.   On the left side of the pack, in line with the daisy chain loops is the vertical zip storage pocket with a key clip – this is a great place to store things like a wallet or phone that you don’t need very often, but want easy access to without tearing through your pack.

The front straps of the pack have as much or more front storage capacity than any running vest we’ve tested, and are secured in place with dual sternum straps that can be vertically adjusted for your preferred fit.  There are two smaller pockets positioned low – one of these has a horizontal zipper closure, the other has a Velcro closure – that can store a handful of gels or even a small camera.  The upper pockets are much larger, and can accommodate a standard 20-oz water bottle or 500ml soft flasks.  These upper front pockets differ slightly from right to left; the left side has a bungee cord closure, and the right has no closure, but has a vertical zipper mechanism to expand or tighten the pocket as necessary.  On top of the right upper pocket is one more small mesh pocket that is perfect for stashing gel wrappers or other trash you acquire along the way.

UD fastpack 20 front pockets

One drawback about the front pockets is that they are quite water permeable from the interior surface, so if you’re sweating a lot, you should keep things like pills or a smartphone in a Ziploc bag to prevent moisture intrusion.  We’d love to see these straps or at least a pocket or two with a substantial water barrier.

Ultimate Direction infiknit harness

The entire interior surface of the Fastpack 20 features another innovation: an Infiknit harness that seamlessly continues fabric from the inside back panel all the way down the length of the front straps.  There are no seams anywhere against your body, virtually eliminating any chance of chafing from the interior fabric.  The padding against the back is rather thin, and if you don’t have a hydration reservoir between your back and your cargo, you’ll definitely feel the contents of the pack against your spine on long days.

Back to the cargo issue: although the pack can easily carry in excess of 20 L, if you’re going at a decent clip, large loads tend to sway back and forth noticeably more in the Fastpack 20 than they do in a more traditional backpack-style setup with a waist strap.  The Fastpack 20 is based off Ultimate Direction’s Signature series of vests that are meant for light and fast movement, which is why a vest style was chosen for this model.  When you’re walking, the sway isn’t that big of a deal – so as you load the pack closer to capacity, it becomes better suited as a day (or overnight) hiking pack than a running-compatible pack.  The tipping point in this equation seems to be when the pack is about two-thirds full: less than that, running is no problem; exceed that, and you’re better off fast hiking.

ultimate direction fastpack 20 tetons

Taking in the Tetons

The Good

  • Outstanding cargo capacity in comparison to overall weight
  • Plenty of storage options on all sides of the pack, including good capacity on the front straps
  • Roll top and strap system compresses main compartment easily and effectively
  • Comfortable fit from seamless interior padding and straps

The Bad

  • Hydration bladder not included
  • No water barrier in front pockets
  • Cargo sways when overloaded

The Bottom Line: Ultimate Direction Fastpack 20

Ultimate Direction’s Fastpack 20 is a highly capable pack for all-day or light overnight trail outings.  The minimalist approach to this pack generally works very well, unless you’re going both high-speed and high-capacity.  Otherwise, it’s a very comfortable and functional pack for a wide variety of outdoor adventures.

Buy Now: Visit UltimateDirection.com

Written By

Donald is a physical therapist, ultrarunner, barefoot aficionado, and father of three with more than 20 years of experience in endurance sports. When he's not training for ultramarathons, he enjoys hiking or slacklining with his family in Monterey County, CA.