Sierra Designs Flex Capacitor 40-60 Pack

SKU: SDSPFC40

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Questions & Answers

Josh W : Would this be appropriate for an 11-year-old who's just under 5 feet and around 100 lbs? I want something he can grow into but will work for shorter trips now.Sunny S : The size to get depends more on the torso and hip fit; if the torso length is between 16" - 19" (40.6 - 48.3 cm), get the S/M Torso; if the torso length is between 18" - 21" (45.7 - 53.3 cm), get the M/L Torso.
Shopper : So.....is there a size chart to figure out what size––torso length and waist––work for me???   I couldn't find a size chart here.   I'm 6ft and 165lbs.   I would like to buy the S/M TORSO size.   Will it work???  Thanks.    ~ Michael ~Sunny S : The only specs available for this item in terms of fit is the following: Hip Fit with S/M waist belt: 26" - 38" / 66 - 97 cm Hip Fit with M/L waist belt: 33" - 48" / 84 - 122 cm
Shopper : Why Did You Choose This?JODI P : For my husband.SHAWN W : Incredible design, comfort, and adjustability.RON F : Well designed, reputable company, great price.MYERS J : Best price in the webiverse.TOMMY P : Good online reviewsDEBORAH M : Because it is light

Reviews about this item

Review Summary

2023-03-20T20:00:00

Rated 5 out of 5

Super nice

No, I have yet to do a full test with this pack but so far I love what I can put in there and how it packs in. I like the way it sends out or fat is up instead of gets taller. Plenty of adjustments and very comfortable to wear. Looking forward to giving it a full test on a big trip.

Joel W.

2023-02-22T19:00:00

Rated 5 out of 5

The best backpack I have.

The best backpack I have. It's quite reliable, spacious, comfortable, with convenient pockets on the straps and waist belt.

Oleksandr P.

2023-01-23T19:00:00

Rated 4 out of 5

good design

I really wanted this pack to work for me as it has just the features I want. However I fell between sizes and just couldn't get comfortable with my max load of 40 lbs. I think if it fits you you'll be very happy

Jeff Y.

2023-01-18T19:00:00

Rated 5 out of 5

Comfortable and lightweight

Comfortable and lightweight backpack. I like everything about this backpack but it needs to be tested on a hike.

OLEKSANDR V.

2023-01-18T19:00:00

Rated 5 out of 5

Flex Capacitor 40-60

This pack is awesome. It replaces at least 2 packs by expanding from 40-60 liters. Quality from Sierra Designs is superb. The front shoulder and hip pockets are fantastic for holding odds and ends that you want quick access to while hiking. I can't say enough about how great this pack is. Just buy it, you won't regret it.

Andrii I.

2023-01-04T19:00:00

Rated 5 out of 5

This pack really distributes load well and it's light weight. Gives frameless ultralight packs a run for their money.

I really like this pack. I'm able to pack tons of stuff inside. It fits my inflatable sleeping pad, quilt, 2 person tent, all my stove and cooking supplies, pillow, water filter kit, puffer jacket, rain/wind breaker, spare socks, TP, and a full size backpackers cache bear canister inside. Outside I'm able to strap half a foam sleeping pad to the back for my dog to sleep on and to use as a place to sit while at camp. There is also room inside for a water bladder and storage for Nalgene bottles on each side of the pack. I've had framed packs from competitors in the past and loaded them with this much stuff and they didn't feel as light as the load does in this pack. It's really impressive how the Y frame distributes the weight. I'll be picking up a 60-75 liter model next. The performance far exceeds the retail price of these packs!

Brian

2022-10-27T20:00:00

Rated 5 out of 5

Great pack

Lightweight and comfortable and easy to use.

steven p.

2022-10-06T20:00:00

Rated 5 out of 5

Nice pack

I have wanted it for a long time

Serhii K.

2022-09-05T20:00:00

Rated 5 out of 5

My Favorite Backpack

This is my third Flex Capacitor in my family. We love this pack! It's features are durable and comfortable. I love it's ability to be fast and light for weekend trips, and big and heavy for up to 10 day trips.

Keno G.

2022-07-31T20:00:00

Rated 5 out of 5

King of expansion

So the game is always only take what you need, but in my experience, things start out tidy and tiny and neat and orderly. Half way thru the trip or trail I find I can no longer maintain the perfection that was when I started. No big deal this thing expands and punches way above its weight class. Everything is easy to get to, and I find this is my go to for 4-14 days out on the trail. I really cannot wait to use it more.

Sam R.

2022-07-18T20:00:00

Rated 4 out of 5

Nice light backpack

I got this backpack a couple of months ago for a trip out west. My kids are old enough now to carry their own loads so I figured it was time to get a smaller and lighter backpack for myself. This pack is very comfortable to me and fits me well, I'm 5"10 and 200lbs. The one thing I don't like about it is the top pocket. It can hardly hold anything at all as it is very small, it seems like an afterthought. I feel like it should be a little bigger or just not have it all. Other than that this pack does exactly what it needs to do. Help me haul my stuff from campsite to campsite in a comfortable manner!

Joshua M.

2022-06-29T20:00:00

Rated 3 out of 5

So much potential...

Pros: Pack body, frame, compression system, zip lid, hip & shoulder pockets pockets are outstanding. All those components are essentially perfect for me. Cons: Shoulder straps and hip belt do really not live up to the rest of the pack. Shoulder straps too narrow and stiff and rub into collar bone. Hip belt too thin, unsupportive and cants/tilts with a moderate amount of weight. To combat this you have to really crank down, and since cushion is sub-standard, hurts the hips. Needs to be a better transition from the lumbar pad to hip belt (see Mystery Ranch packs for an example of how it's done right). They should ditch the mesh side water bottle pockets and make them solid fabric for durability. Lastly, sizing really needs to go back to separate small, medium, large for torso.

Nick T.

2022-06-29T20:00:00

Rated 5 out of 5

Great find!

I did a lot of research, looking for a backpack, and this one does not disappoint! It's a great size and sits very comfortably, i would recommend it to anyone and will definitely buy another one myself

Lindsay D.

2021-10-06T20:00:00

Rated 4 out of 5

Nice pack but fit issues

This is a well conceived and well built pack. And it supports a heavy load -35 lbs for me - well. The shoulder pockets work well for 1/2 L or 3/4 L water bottles. The only negative comment is with the fit. I have an 18" torso and the s/m is slightly too long for optimum shoulder fit. I'd say the minimum torso length would be 19". SD should never have nixed having three sizes since there is no torso length adjustment. For example, the REI Flash 55 has three torso lengths available, which greatly increases the chance for a good fit. I'm keeping this pack, however, despite the less than great fit since I'm beyond the return window.

Gear u.

2021-09-12T20:00:00

Rated 5 out of 5

Perfect pack

The Flex Capacitor is the perfect pack for a 1-5 day backpack, in my opinion. This is the most comfortable pack that I have used to date, the weight distributes perfectly, and the exterior pockets are amazing. Works great as a day hike pack from basecamp, no need to bring an extra pack.

Christie D.

2021-08-08T20:00:00

Rated 4 out of 5

Flex

Felt really good on my back almost like I was not carrying anything at all. One of the water bottle pockets got a small rip 10-20 uses and I can't tell you how. I wish it had a couple of side pockets but all in all it is my favorite overnight pack I own 4. I thought the water bottle pockets on the shoulder straps were dumb until I used them, after which I loved them!!!

Mark h.

2021-07-26T20:00:00

Rated 5 out of 5

AT Ready

All practice hikes and shake downs. The pack is performing well. I look forward for the through hike on the AT.

Dale C.

2021-07-19T20:00:00

Rated 5 out of 5

Great Versatile, Affordable, Rugged Backpack!!!

I spent years borrowing my friend's 15-year-old Kelty backpack, and I was first struck with how amazingly light the Flex Capacitor was in comparison. I am a 45-year-old, 5' 9", 140 lbs casual hiker and backpacker. As I get older, carrying weight becomes more difficult, so its light weight and comfort level was a big factor in my purchase of the 40-60 Flex Capacitor in May, 2021. I've been extremely happy with the design and versatility of the pack. I recently disassembled the Y-frame to take the pack as carry-on luggage on a flight, and with some practice, it was easy to disassemble and reassemble. I also really like the flex design with the gusset and straps to shrink/grow the volume to keep things tight and comfortable. I have so far mostly used it as a day pack on longer hikes, and the various pockets have served me well for quick access to water, rain shell, snacks, and places to stow trekking poles and hats/helmets. I was a bit concerned about the ruggedness and longevity of the pack given its light weight, but no more: I just returned from a hike where I put that to the test. On a 13-mile hike wearing the Flex Capacitor in RMNP, I began to have some altitude sickness above 12,000 feet, and with weather changing we decided to bail. If you've had altitude sickness, you'll understand that I just wanted to get off the mountain fast and feel better, so at times I did a bit of screeing down the talus field, where my rear end and bottom of the pack slammed and scraped across the rough and sometimes sharp talus boulders. In the back of my mind, I was ready to kiss the bottom of my Flex Capacitor good-bye, but to my surprise it held up without any signficant tears or deep abrasions! I have not yet used the pack fully loaded, but am going on a 4-day 40-miler in September and have no doubts that the pack will serve me well.

Adam

2021-06-13T20:00:00

Rated 4 out of 5

Great pack, didn't fit right.

I really love the flexibility of this pack with the compression capability, sturdy frame, and comfy hipbelt (all in a pretty lightweight pack). It's didn't fit me quite right, though. I have a pretty short torso for my height(18in), and I couldn't get the shoulder straps to fit properly. This would be a great pack for someone with a slightly longer torso.

Matt M.

2021-06-02T20:00:00

Rated 5 out of 5

Very comfortable carrying heavy loads, great features!

I love this pack. I carried 30lb and it didn't feel like a thing! The frame is very comfortable. It doesn't poke at odd places and the pack fits like a glove. This has to be the lightest pack out there that can carry a heavy load comfortably. Other features that I found extremely useful - large hip belt pockets that can fit any phone, the mesh shoulder pouches to keep a small camera handy, the side pockets are durable and stretchy - a nalgene won't fall out. My only complain would be that all the straps make the pack really messy, which annoys me. A nice mechanism to stow the straps or tuck them in somewhere would be nice.

Nitish G.

2021-05-26T20:00:00

Rated 5 out of 5

Great pack with phenomenal customer service

I purchased this pack 2 years ago and have used it on quite a few trips since then. The pack is very comfortable keeps the center of mass close to you back for good control and has many well thought out and executed ideas and designs. I love how it compresses. A few months back I ripped the water bladder reivoir

Max W.

2021-05-12T20:00:00

Rated 5 out of 5

Wow! Just wow!

I have the 40-60 as well as the 60-75 and I've been very impressed. When I originally bought the 60-75, I was immediately impressed with the build quality, comfort, and weight. After a few times out, I decided the 60-75 would be great for a week long adventure, but I tend to pack pretty light didn't quite need as much room. When I picked up the 40-60, it did not disappoint. With all the things I love about the 60-75 but just a bit more compact, it has quickly become my go-to backpacking ruck.

Nicholas L.

2021-05-05T20:00:00

Rated 5 out of 5

5 Days of Comfort

I used this pack for 5 days in Southern Utah and it stood up like a champ. It was comfy around my waist & it had plenty of room for my food and gear. I'm 5' 7" 150 lbs and the S/M fit perfect. If I would have one gripe with this pack it would be the wide pockets. They can be a little too loose depending on the gear you fit in there. But I am being picky.

Joseph P.

2021-03-24T20:00:00

Rated 5 out of 5

Great Backpack!!!

My favorite thing about the backpack is how comfortable the hip belt is. I just completed a 25 mile hike and my hips back or shoulders never got sore. I love this pack. If I had to change anything...perhaps some outer storage pockets would be helpful and the large zipper on the top kept getting stuck by the large piece of fabric that folds over the zipper. There was one time where I wasn't sure if the zipper would be unstuck as the fabric was completely inside of the zipper but I was able to get it to release. Just be careful when zipping up the top. Other than that it performed very well and I'd definitely recommend it to anyone!

Cameron H.

2021-03-20T20:00:00

Rated 5 out of 5

well done Sierra Designs

Very conferrable. Carries more weight than it should for its weight. nice sized hip belt pockets. Extremely well priced.

JOHN J.

2021-03-02T19:00:00

Rated 4 out of 5

Y Flex DAC

Hello, A French website says that it is easy to disassemble the "Y Flex DAC" frame. This is the reason why I bought this bag, but I can't find how to do it. Thanks for explaining to me. Jean Louis

Jean-Louis

2021-01-28T19:00:00

Rated 4 out of 5

Aaalmost perfect...Grrreat SCOTT!

I spent months researching packs online and going to outfitters to test how they fit. I'm a huge Back to the Future fan, so the Flex Capacitor caught my attention. Turns out it has all the features I want in a pack and is still cheaper/lighter than the others I was considering...but I was unable to try this on before purchasing. Because no other packs checked off all the boxes on my checklist, I took a chance. My Pros: - Hip belt pockets are slightly larger than on other packs and fit my iPhone 8 in an Otter Box case perfectly. - S/M actually fits my 28' hip just fine with a couple extra inches of tightening space. (Perhaps my pants + belt give me the couple extra inches I need to fit the posted measurement?) - Brain is non-removable and isn't unnecessarily bulky. - Water bladder sleeve is removable. - Shoulder strap pocket with cinch cord perfect for a water bottle, snacks, phone, etc. - 1 simple top-loading access point. My Cons: - While the lower-back and scapula pads are very comfortable...they are not very breathable...so those are the exact spots that get sweaty. - With a heavy (>30 lbs) load...it puts pressure on my right clavicle leaving it sore. I can mitigate the pain by shifting the shoulder strap just very slightly any time I feel it hurting. No pain on the left clavicle at all. Not sure why.

Ken S.

2020-12-27T19:00:00

Rated 5 out of 5

Pack review

So far its an awesome pack very comfortable and light weight. I have only taken it out when its cold out. I do have a small concern with how my back will breathe during the summer there is no airflow between my back and the pack. I was worried about the shoulder pockets if my smart water bottle would fit there and if it was going to bother me. The bottle fit and it was no bother. I really like the tightening straps for the waist belt it is awesome.

Rene F.

2020-11-25T19:00:00

Rated 4 out of 5

Love this pack

Almost the perfect pack. The side mesh pockets for water bottles needs to be a little deeper. The high tension spots need a little more fabric because they are super stressed out and I see durability issues. Otherwise I love it. Fits perfect, love the compression straps and versatility. Right now I?m waiting to hear back from SD for repairs on those seams that have stretched and torn after 12 miles. Definitely need to tread light on this pack, it?s the trade off for its weight.

Terry B.

2020-11-17T19:00:00

Rated 5 out of 5

Great

Price, Weight, Function.. Great items.

Namhee K.

Sierra Designs Flex Capacitor 40-60 Pack Specifications

  • Source

    Imported

  • Materials

    100D Nylon-Poly Ripstop/420D Nylon Oxford

  • Capacity

    42-60L (2563-3661 cu in)

  • Torso Fit

    18 - 21" (45.7 - 53.3cm)

  • Suspension

    Y Flex DAC

  • Hip Fit

    S/M waist belt: 29 - 32" (73.7 - 81.3cm)
    M/L waist belt: 32" - 35" (81.3 - 88.9cm)

  • Dimensions (H x W x D)

    27.5 x 11 x 10" (70 x 28 x 25.4cm)

  • Weight

    S/M waist belt: 2 lbs 9 oz (1.16kg)
    M/L waist belt: 2 lbs 10 oz (1.19kg)

  • UPC Code

    054003819503

About Sierra Designs Flex Capacitor 40-60 Pack

FEATURED REVIEWS

Favorite Pack in My Gear Closet (and i have many)

By Jo O.

I have been field-testing backpacks for 25 years,* and have a list of favorites (ones that work best for me, and ones that I think work best for a wide range of backpackers). The Flex C meets 95% of my needs/demands: it offers a perfect balance of pack weight-load capacity (I test it up to 55 lbs., a third of that water), it fits comfortably, stays put and carries loads (even beyond capacity) well. It also offers a nice balance of simplicity and adjustable volume. (Compression straps extend l...

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What a lovely bagpack!!

By hobae

I'm a south korean. we have to pay additional tariff if we buy something over USD 200 from US. when I decided to buy this backpack it's price was about USD 205 including tax. I asked a clerk to give me a discount coupon by e-mail, the clerk willingly sent me the 25% discount coupon. I really thank him so much. the price is so reasonable, design is very nice especially going well with my black clothes, comfortable, and maximum load is so high despite of light weight backpack. my favorite thing...

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Presenting the Sierra Designs Flex Capacitor Pack Series, a trio of backpacks that redefine versatility. Each pack in this impressive line-up is equipped with an adjustable volume feature, designed to cater to both short expeditions and long, ambitious adventures. The secret lies in the Flex Capacitor's Y-flex suspension system, a standout feature that enables the pack to comfortably bear loads beyond its weight class.

The Flex Capacitor comes in three sizes for optimal adaptability - 25-40L, 40-60L, and 60-75L. Whether you're on a quick day trip or a week-long backpacking journey, there's a Flex Capacitor Pack tailored to fit your needs. Every pack in this series features a practical bucket lid with a stash pocket for convenient storage, and dual stretch pockets on the shoulder straps and sides to handle your 'shove it' needs.

The Flex Capacitor series boasts an ultralight design complemented by a 'Y' Flex DAC suspension system, establishing a fine balance between lightness and robust support. These packs also provide multiple storage solutions including zippered hip belt pockets and a U-shaped top access zipper for quick and easy access to your belongings.

Select the Flex Capacitor Pack Series - the perfect fusion of versatility, comfort, and efficiency for all your adventures.

Sierra Designs Flex Capacitor 40-60 Pack Features

  • Expandable Volume
  • 2 stretch mesh side pockets
  • 2 stretch mesh hydration pockets on shoulders
  • Zippered hip belt pockets
  • U-shaped top acces zipper
  • Small stash pocket in lid
  • Ultralight weight
  • Lightweight 'Y' Flex DAC suspension
  • Sierra Designs Lifetime Limited Warranty

Warranty Information

This product has a limited lifetime warranty.

Key Features

  • Adjustable volume for tailored packing solutions
  • Lightweight 'Y' Flex DAC suspension for heavy load support
  • Three size options for optimal adaptability
  • Multiple storage solutions for on-the-go convenience
  • Ultralight design for comfortable, easy carry