Ultimate Direction Fastpack 20 Review

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Scott & Don

I love fastpacking and have over the years tried to keep the load “light” and try to only bring the essentials.  The Ultiimate Direction Fastpack 20 is a great start to the merger of fastpacking and ultrarunning.  It’s the right size for very very long training runs and for short 2 to 3 day fastpacking trips.  Let’s take a look at the Fastpack 20.


The pack (med/large) came in at 17.65 oz (without the pad).  The back pad came in at 3.15 oz.

1 front and back empty

Lots of storage.

2 right side pocket


3 inside view pad removal

4 inside and hydration port view

Some highlighted features:

  • Large, main roll-top compartment expands from 15L to 23L
  • Rear stretch-mesh pocket with low-profile daisy chain system
  • Water bottle compatible front pockets also fold flat to store other items (GPS, etc.)
  • Dual adjustable sternum straps and side straps for great stability and fit
  • Integrated side compression Z-straps for varying load capacities

Some special features:

  • Infiknit harnessis a continuous, seamless back panel and shoulder strap system to prevent chafing
  • Removable foam back panel to insert your own pad, ground cloth, etc. (limitless options)


The first test on the trail was for a 6+ hour training run – plenty of storage for hydration, food, gear, etc.  The load easily cinched down with all the adjustments on the pack.  UD has nailed the Fastpack 20 for ultrarunning (like all their other packs). If you need to keep any items in the front vest storage pockets dry (pills, electronics, etc.), you will need to put them in a ziplock bag. The perspiration goes right through the interior of the vest harness.

The real test for me was to take it on a 2 to 3 day fastpack trip.  I kept my base weight (gear weight in the pack without food and water) under 10 pounds (159.55 oz, 9.97 lbs).  See gear list below.

base weight

See loaded pack below.

5 front back loaded

6 side view loaded 7 bungy stash pocket 8 top view loaded

When the pack was loaded, it ranged from 14 to 19 pounds (depending on the amount of water and food that was being carried).  The pack was comfortable at 19 pounds hiking and run/walking.  The load could be slightly heavier if you want to only hike and not run.

For continuous running, the pack tended to swing at loads greater than 16 pounds.  With the vest design eliminating the waist belt, the swing will occur at some point for each individual depending on how the pack fits (maybe UD should size the pack by small, medium and large versus small/medium to medium/large).

Overall, a great first version of a fastpacking/ultrarunning pack. Remember to keep your base weight light.


The Good

  • Great pack that merges fastpacking and ultrarunning
  • Great for long hikes, long training runs, and 2 to 3 day fastpack trips
  • Comfortable for running for loads around 16 pounds
  • Lots of storage in the stretch mesh back pocket
  • Love the option to remove the pad to use my own pad/group cover (or whatever you want to stash)

The not-so-Good

  • Not comfortable for running with loads greater than 16 pounds (pack tends to swing) – but hey, you should keep your base weight down.


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