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  • Ultimate Direction: Fastpack 20

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Fastpack 20

$159.95 $127.96
Out Of Stock
New for Fall 2014

Providing all the features and capacity you need and nothing more, the Fastpack 20 is a streamlined pack that will get you there and get it done. Perfect for day hikes, peak bagging, or a quick weekend, the Fastpack takes inspiration from our Signature Series vests, with its super stable and comfortable fit.

There is easy access to water, maps or your phone on the front, the stretch pockets on the sides will hold almost anything, and the huge rear stretch pocket allows gear to be quickly stowed or used as needed. The main compartment forgoes zippers in favor of a waterproof roll top closure, allowing this bag to tightly secure everything from 15 to 23 liters. The Fastpack 20 is water-resistant, with a reinforced bottom panel for extra durability, and the low-profile daisy chains with trekking pole and ice axe loops complete the package. 

Unique to the Fastpack is our InfiKnit construction: the back panel and shoulder straps are made from one piece of custom-made fabric, which eliminates contact with all seams.

Media Reviews

Ultrarunner Podcast - June 2014

Specs & Details

  • Patent-pending Infiknit harness is a continuous, seamless back panel and shoulder strap system to prevent abrasion and discomfort
  • 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
  • Dual adjustable sternum straps and side straps for stability and fit
  • Integrated side compression Z-straps for varying load capacities
  • Removable foam back panel for comfort
  • This size qualifies as a "Personal item” under airline carry-on rules
  • Available in 2 sizes
Sizing at Chest (Unisex):

  • S/M: 24" - 40" / 60 cm - 102 cm
  • M/L: 32" - 46" / 81 cm - 116 cm
  • Measure wearing the clothes you intend to wear
  • A pack full of gear will fit smaller

  • Capacity: 15L - 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
  • Product Reviews


    Write A Review

    1. Functional

      Things that stand out: Functional. Simple. Quality construction and materials.

      Only negative I encountered: some smaller items fell out of side pockets when leaning or bending over. Would be nice to have a cinch of some sort to secure items in those locations

      If you are looking for an even more effortless experience then grab body bottles to go with the pack.
      on Jul 27th 2017

    2. best pack for active travel

      Love my new pack. Bought for both travel/commuting and trail running, perfect for both.

      For travel/commuting: Perfect size for planes, great packable shape, and really stable on a bike. Keeps all your valuables up front, accessible and where you can keep an eye on them. Fits a 13" laptop in a thin case in the water sleeve, which also keeps it slightly off the base of the pack. The roll top is perfect for over-filling the pack with groceries on the way home.
      > could do with some reflective detail though, I'd really appreciate this at night times/in rain. I ended up buying a reflective yellow raincoat for it for these times (with the bonus that it keeps things dryer inside). I'm also planning on adding a small loop of webbing on the bottom of one of the front panels for clipping a helmet onto.

      For running: To give you an idea of fit, I'm a 5'4" female, borderline between female small and medium sizes in most brands. When virtually empty, I have this fastpack pulled pretty much as small as it gets. Luckily my C size chest seems to hold the pack down well, to stop the potential bounce of the pack (and bonus - the pack seems also to stop a lot of the bounce of my chest as well). When full (packed with extra clothes and food for a 3 day weekend), the weight made me need to change my stride, but given that, it carried well once I got used to it. If I was planning on lots of multidays in this, I'd possibly consider the bigger one with a hip belt to take some weight off the shoulders. This pack sits slightly higher, which gives good airflow over the lower back, but not great for long, heavier loads. Super big, trustworthy stretch pockets. So far durable, used commuting for about a month and scraped against some sandstone during a couple of weekend runs, and could still pass as new.
      > my only complaint with running is that sometimes the soft bottles bounce in the pouch when they're less than full. Pulling the elastic toggle back to the other side halfway down the pouch would stop this (a modification I plan to do). Also If I don't stick the velcro pocket down precisely my sleeve catches sometimes, I prefer the zip pocket. I do like the second chest pocket for my phone though for quick map and camera action.

      The last thing I'll say is that this bag acts a little like the jackets they give dogs who are scared of thunder... it gives you a nice, comforting hug. Worth a lot when you're alone, in the middle of nowhere, and it starts to rain...
      on May 1st 2017

    3. Fits like a glove

      The Fastpack 20 has quickly become my favourite trail running pack. I generally carry about 4-5kg of water and gear and honestly don't notice the weight at all. I am 182cm and 100kg and the pack fits as though it was made for me. I like the length of the pack. I have a UD Marathon vest and it feels tiny and uncomfortable by comparison. on Apr 23rd 2017

    4. Great pack!

      Very happy with this pack. I purchased it for the Grand 2 Grand Ultra and so far in training, it has been great. Comfortable and does not move around as I run. on Feb 7th 2017

    5. Great for days with a cold start!

      I bought this pack to fill the gap between my vest and my ULA backpack (which is really overkill for running). I'm 5'6" and bought the small. I'm pretty sure the medium would have been too large since I've got the chest straps pulled tight. It doesn't come with bottles or a bladder so you'll need to order them separately, but it's got all sorts of great pockets to store all the random things one might like to carry on a run. For me, this pack would be the perfect thing to carry on a mountain run where it's really chilly in the morning but you need to ditch layers once the sun comes up and you're sweating bullets. My vest was bursting at the seams! on Sep 19th 2016

    6. Bounces way too much for running

      I've owned several UD packs/vests so when I needed something big enough for commuting and overnighters this seemed like a no brainer. When packed with my typical commuting load (~7 pounds) I find that it bounces WAY too much to be comfortable while running. Just jogging in place in front of a mirror I can see the pack bouncing completely off my shoulders. I haven't had this problem with any of my other UD packs nor with the comparable sized REI Flash pack I'm now using. on Jan 29th 2016

    7. Customer Review

      I received this a few hours before a quick sawatch trip with a friend in which temps and wind were matching (20-40) just a week ago. I stuffed it full of gear, microspikes (in a bag), food, a 70oz bladder, two soft bottles, poles, and set off. It worked like a charm. I'm 5'5 and smallish on top and the small fit perfectly with a little room for tightening up as my layers decreased and plenty of room to expand over a puffy, a wind/rain layer, and a couple thin layers beneath. I'm excited to continue to test this for longer mtn days when more gear is required than I can fit in my running packs. It rides like a running pack and has so much room to expand I cannot wait to experiment. Thanks! on Oct 21st 2015

    8. Customer Review

      Used this pack during a 600 mile run from Missoula to Banff. It rides well even when nearly empty. With a full overnight kit (and camera gear) it carries well too. For cold weather overnight trips, where you need more layers and a larger sleeping bag, the Fastpack 30 may be a better choice. The pack is durable and held up very well after many miles of off trail travel and scrambling in rocks. Some days it rained and snowed for most of the day and the pack kept everything dry inside. It will bounce, when fully loaded, while running especially if you don't pack heavy items close to your back. This is now the vest I grab for full day mountain adventures as it rides as comfortable as my Salomon vests that I normally use. on Oct 11th 2015

    9. Customer Review

      I couldn't figure out where to carry my camera. On my GoLite Rush24 I have a Lowepro Dashpoint 30 case on the shoulder strap where the sternum strap connects. The Fastpack's front pockets are too small for anything but a pocket camera and the shoulder straps are too wide for the Lowepro case. I asked customer support and they said to carry my camera in the backpack! I want to get my camera out without taking off the backpack. I like my GoLite pack because I can get to everything I need when I'm on the move without taking off the pack. I'll give two stars because getting a return authorization was easy. on Sep 25th 2015

    10. Customer Review

      Invested in my Fastpack20 for the Bigfoot 200 this summer. I used it last weekend for the Georgia Deathrace: 68 miles with 40,000' of elevation change, billed as the toughest race east of the Rockies. Despite packing it heavier than I was used to, I never really noticed it during the run, never felt it was slowing me down, never had sore shoulders. It stayed put and didn't bounce around. We were required to carry extra layers and an emergency blanket; these all went in the rain-protected main compartment. We had to have capacity for 40oz of water; two water bottles in the front worked nicely to balance the load. I was late acquiring my gels and had to carry all 24 of them the whole race instead of putting some in drop bags; the side pockets and quick-access outer rear compartment worked great for these. All in all, I am very happy with this purchase. on Mar 18th 2015

    11. Customer Review

      I love my Fastpack 20! I've used it on extended unsupported runs (160 miles of the John Muir Trail) as well as on multi-day peak bagging expeditions, and on several rock climbs and technical mountain ascents where I needed to carry a helmet, crampons, rope, harness, etc. The Fastpack easily swallows all the gear I need, yet still carries comfortably enough to run. on Feb 27th 2015

    12. Customer Review

      I have enjoyed using this pack on longer unsupported runs. I used it for circumnavigating Mt. St. Helens and then summiting it. It was perfect for an all day adventure even though it can carry enough gear for overnight trips. I even used it to put all my beach gear in when hanging out on the beach in Oahu! It's stylish and useful. The fit is great, I'm 5'8" female and I have a size small/medium. on Jan 30th 2015

    13. Customer Review

      Have carried up to 3 days (~17 lbs) worth of food and gear in the pack. At this weight, proper placement of items within the pack and compression of straps was important to keep things comfortable. There was some bouncing when running at this weight but it felt surprisingly comfortable while hiking. I will try and keep things at <14 lbs on future backpacking trips. Full coverage on your back so expect some sweat during hot weather or high physical exertion. Two stretch pockets on the side easily accommodate bottles, feel secure, and are accessible with the pack on. Usually, I kept one 20oz bottle in the bungee pocket up front and a map and camera in the other. Tons of space for food in the zip and Velcro pockets, too. The pack is very comfortable to run with at lighter weights and cinches down tight when your load is small. I'm a 38" chest and sized up to the M/L to accommodate the full pack size. The straps are almost fully tightened when the pack is not full but I haven't had an issue keeping it secure. I think I would have ran into issues with the S/M and a full pack. Overall, excellent pack with a unique setup (compared to hiking packs) that fits your body like a shirt. As the name says, great for multiday running/hiking trips and fastpacks as long as you keep the weight down. on Dec 25th 2014

    14. Customer Review

      UD - please size your products for women too! I purchased this pack in S/M. If I cinch down all the straps and the pack is full, it is ok for short distance, but moves around quite a bit and is overall way too big for me. Admittedly I am a very petite person, but I imagine that there are many other gals like me who purchase your gear. I hope you will consider us smaller sized women in all your products, and offer an XS size rather than making a special women's version. I don't want a pack that's toned down from the original in any other way than sizing. I'm still using my pack, but won't be able to use it for the longer distance traverses I planned on using it for. on Dec 8th 2014

    15. Customer Review

      I purchased this pack for primary use as a daypack while hiking. I brought this with me on a 5 day hiking trip through Canyonlands National Park in late September. I like the pack very much. I typically carried 4-5 L of water in the pack each day and the pack carried that with ease. My 2L platypus collapsible bag was kept in the hydration sleeve, a 1L platypus kept inside the main bag, a 1L smart water bottle in the left side mesh pocket , a 500ml UD soft bottle was kept in the right zip pocket/sleeve on the right shoulder strap and another was kept in the right mesh pocket with the small cord loop to secure it. I was able to use and transfer water from place to place quite easily. I appreciate the loops for trekking poles and the small secure cord loops on the daisy chain. I kept my cell phone (used as a camera in airplane mode) in the left front pocket with the cinch cord - worked great! I wish the two small pockets on the bottom of the shoulder straps had a bit more volume but they were okay. I had plenty of room in the main pack volume for food, 1st aid kit and rain gear - loads of room to spare -and the back mesh pocket is great. I love the small secure zip pocket on the side for credit card, driver's license and cash/key. The forest green color is okay but not my fave and so wouldn't mind a brighter color or two to choose from. on Oct 10th 2014

    16. Customer Review

      Ran in this pack a few times and just did a 3 day hike and run in the Alps with it. Rides great even when fully loaded! You can fit a ton of gear in it which is great. Love the big mesh pocket in the back! However would have felt more secure if the three mesh pockets (the back and two side ones) had a draw string to keep them tight but maybe its just psychological because nothing ever fell out and I used them a lot. Personally i found having one 750 ml bottle in the left front pocket with an extra 750 ml bottle in the right side side pocket worked best (compared to having both bottles up front). It gave room to have easy access to a camera and bars etc in the right front pocket. Also having two 750 ml bottles in the front didn't sit so well on me, but one in the front and one in the side was awesome! The pack sits well while running and straps are very comfortable. Agree that more colors would be fun but personally I would choose this green anyway, think it looks nice! Great pack and already recommended to friends who now also own it! on Sep 14th 2014

    17. Customer Review

      I'm a long time Ultimate Direction devotee and have owned every generation of hydration pack UD has developed. The Fastpack 20 is an excellent pack. As a 6' tall/140# female, I purchased the M/L. I probably would get a better fit with the S/M, since I have the adjustments cinched to the tightest fitting. This is a great pack that rides nicely with loads below 10#. Even though the capacity is huge and could carry more than 10#, I wouldn't load it with more than that. Without top load lifter straps, too much weight will cause this pack to sag and weigh heavy on the shoulders, or pull outward (as I have seen in photos of product testers who had the pack fully load). I have not used this pack on overnight adventures yet, but only on day run/hikes and as a pack to "run" errands. Two design elements that were overlooked are: one of the front hydration bottle pockets could have been made to zip closed and used as a secure pocket. There are no zippered pockets large enough to secure a phone/wallet etc. I would have like to have seen load lifter straps on the shoulders, so that the if the pack is loaded it could be adjusted upward to prevent sagging. Brighter pack colors would be great for visibility--bright blue, orange or neon. The dark green is drab. But I do like bright colors, so that's just my personal opinion. I give this pack 4.5 stars and highly recommend it! Can't wait to try the Fastpack 30L on Sep 12th 2014

    18. Customer Review

      Ordered the pack when it release, used it for few hiking trip. Awesome pack and pretty good rain-proof. Like the signature series, it is very comfortable and no chafing when wearing, if the backpack is too full, it maybe a bit bouncy but that is not the design fault. The front bottle holder is big enough even for a 750ml bottle, but 500ml soft bottle give the most comfort and fit. On the right side I use it to put a small digital camera and my phone, and they are very secure. The small pocket below can be used to put pills, keys and plenty of room even for a card wallet . The mesh pockets at the side are deep enough for gatorate bottles, sunscreen, snacks and other stuffs. The pocket at the front can store my jacket, umbrella and maps securely without have to worry to lost them. There is also a small compartment on the side for keys (with a loop) and my wallet, headlamp and it seems to be waterproof. Inside compartment is HUGE, probably can fit everything else you need for 1-3 days trip in it, I have removed the back panel to reduce the weight and it is still comfortable, but since there is only one compartment for hydration bladder and a general compartment, it is very hard for me to "dig" out the item I need if I put a lot of things in it. I am very pleased with this purchase, and it will be great if UD can have more choices of colors (like blue). on Sep 11th 2014