Backpacking - Hiking



Do you like to simplify your life by having a single piece of gear that can be used in many different situations?  The Flex Capacitor 40-60 is the backpack that will work perfect for a weekend trip to your local trails or an extended hike into the backcountry. 

Just the Facts:

The lightweight backpack of your dreams is here. Meet the versatile pack that hauls it all. The Flex Capacitors is a beast of backpacking pack, constructed from durable nylon for rough conditions in the backwoods and built with adjustability in mind. Loosen the expanding horizontal gussets for an additional 15-20L of cargo capacity on longer backpacking trips, or cinch it tight for smaller, compact loads on fast summit days. Plus, ample quick-stash solutions on the straps, sides and bucket lid ensure there are plenty of places to store your mid- trail essentials. However, you pack it, the Y-Flex suspension adds support so this lightweight backpacking backpack can hit well above its weight class. Flex Capacitor Rain Cover sold separately. 


  • Lightweight Y-Flex Suspension provides superior increased support.
  • 20L adjustable volume to tailor both to extended backpacking trips or shorter day trips.
  • Hydration sleeve doubles as removable summit sack.
  • Dual adjusting shoulder straps tailors pack fit to your torso.
  • 2 hydration pockets on shoulder straps.
  • 2 stretch mesh side pockets to keep essentials close at hand .
  • Zippered hip belt pockets for easy storage.
  • U-shaped top access zipper for easy access while backpacking.
  • Lightweight backpack.


  • 100D Nylon Honeycomb/420D Oxford

Technical Specs:

S/M Torso

  • Capacity: 40-60L / 2441-3661 in3
  • Weight: 2 lbs 12 oz  / 1.23 kg
  • Torso Fit: 16″ – 19″ / 41 – 48 cm
  • Hip Fit with S/M waist belt: 
  • Dimensions (H x W x D): 25″ x 12.5″ x 12.5″ / 63 x 20 x 32 cm
  • Suspension: Lightweight Y-Flex 
  • 80710223

M/L Torso

  • Capacity: 40-60L / 2441-3661 in3
  • Weight: 3 lbs 2 oz  / 1.4 kg
  • Torso Fit: 18″ – 21″ / 46 – 53 cm
  • Hip Fit with M/L waist belt: 
  • Dimensions (H x W x D): 27.5″ x 8.5″ x 12.5″ / 70 x 22 x 32 cm
  • Suspension: Lightweight Y-Flex 
  • 80710223

My Story:

I love every second I get to spend in the woods.  Being away from the hustle and bustle of daily life, the chaos of people, and unplugging completely from the world.  Being deep in nature is how I reset and keep my sanity.  Getting far enough into the woods to get away from it all requires having the right gear.  The most important piece of which is the backpack.  It allows you to carry all the rest of your essentials.  The biggest problem with selecting the right pack is trying to narrow down what will be your predominate usage and needs. Do you need a small pack for an overnight or weekend getaway, or do you need a larger pack for an extended excursion.  With the Flex Capacitor 40-60 now you don’t have to wish you could go back in time to second guess your decision.  This pack will be exactly what you need for all situations.

Like most people most of my packing trips are done on long weekends when I can squeeze in an extra day or two away from work with the occasional weeklong trip each year.  Also, like most people, the older I have gotten the more gear I have accumulated.  Don’t get me wrong, I always love having more toys, but I am starting to run out of storage space from all my hobbies.  Having a single pack that fits all my backpacking needs benefits me in the field and at home.

When I first saw that Flex Capacitor I was really excited and intrigued to get my hands on it.  This pack has it all when it comes to your storage needs.  A 40-60 liter adjustable capacity with easy to use cinch straps, top lid zip pocket, vertical mesh pockets on both sides, two zip hip belt pockets, two bottom “water bottle” storage pouches on both sides at the bottom, and two quick cinch shoulder strap pockets.  This pack has all the quick access storage you could ever want and need.

When the pack first arrived, I was admittedly not ready to hit the trails, I had a little excess “winter” weight that I needed to shed before I was ready to spend some quality time in the woods.  I immediately got to work preparing for the first planned pack trip of the year.  I started out putting minimal weight in the pack and hiking a couple mile loop with about 700 feet elevation gain.  Every week I increased the amount of stuff I placed in the Flex Capacitor, slowly increasing the weight to condition myself.  After a month I had to open the cinch strap gussets to increase the volume of the pack.  I was loving the flexibility this pack provided.  Whether I had minimal gear or a lot I was able to snug the load down, so it was not flopping during my hikes.  This feature was only one of a few that that made this pack one of the more comfortable packs I have ever used. 

The weekend came for my first backpack trip with the Flex Capacitor.  This trip was just going to be a long weekend as it was all I could squeeze out of my busy work schedule.  I packed the Flex Capacitor and was in love with all the storage options for quick easy access to my gear.  I had a long sleeve shirt tucked into one of the mesh shove-it pouches, my phone in a shoulder cinch pocket, mini candy bars for quick energy in a hip pocket, lunch/trail snacks in the other shove-it pouch, water bottle in a bottom side pocket and my dog’s leash in the other, the list goes on and on.  I had so many options for where to stash the gear I like to have quick access to I had to take a minute and plan out where I wanted each item.  To top it all off, once all my gear for the weekend was packed up, I cinched down the expandable straps that make the Flex Capacitor so unique, tightening the load so it would carry well, close to the body, and not shift around on the trail. 

I got to the trail head and strapped my trusty hiking companion’s (my black lab) pack on here then tended to my own pack.  I adjusted the shoulder straps, clipped in the hip belt, tightened the load lifter straps, and started the adventure.  The first thing I noticed was the lower back pad on the pack.  My typical pack has more uniform back padding that provides contact throughout most of your back.  The Flex Capacitor is noticeably different.  The lower back pad was more of a small pad that centered on your lower back.  There is some separation between it and the mid/upper back padding. I was a little nervous for the first five minutes of the trip that I was going to hate this back padding configuration.  My fears quickly faded almost immediately.  The pack was so comfortable the only difference I noticed in the back padding was the increased airflow between back pads helping to keep me cool as I exerted myself.

Sierra Designs created the Y-shaped F-Flex Suspension to provide the right amount of rigidity with the flexibility to carry a variety of loads and distribute the weight for the most comfortable carrying experience.  The Y-Flex Suspension is a lightweight aluminum Y-shaped frame with a central disk hub that connects the three legs.  This suspension system adds a lot of support and distributes the weight of your gear without adding hardly any weight to your packing keeping light and durable. 

I arrived at camp happy to have made it to our destination.  I took my pack off, pulled all of my gear out and leaned it against a tree while I set up my camp.  My trusty companion took the opportunity to take a much needed break and grab a drink of water while I did all the work.  After setting up my hammock and resting my legs for a bit I unclipped the hydration bladder hold, slipped the day pack on my back with my water, a snack, a long sleeved shirt, and a few other miscellaneous items to branch out from camp and explore our surroundings.  In my opinion, nothing is better than little Easter eggs like these.  The Flex Capacitor stepped up even more in its multiuse compatibility with having the hydration bladder holder able to detach from the pack and become a day pack.  The day pack was perfect for my mid afternoon exploration. 

The Flex Capacitor truly is the one size fits all backpack.  It has the ability to transform for all of your packing needs.  Whether it be for a weekend hike, an extended trip into the backcountry, or just a short hike from your base camp carrying the essentials.  Sierra Designs created the last pack you will need.

Find it Here:

What could be done better?

I would like to see the hydration bladder holder be a little bit bigger.  I use a 3 liter bladder.  I can stuff it in the holder, but when it is completely full, I cannot close the Velcro on the top of the pouch. 

Flex Capacitor 40-60

  • Functionality
  • Value
  • Ergonomics
  • Durability


Do you like to simplify your life by having a single piece of gear that can be used in many different situations?  The Flex Capacitor 40-60 is the backpack that will work perfect for a weekend trip to your local trails or an extended hike into the backcountry.


Adjustable capacity

Lots of quick easy access storage

Detachable summit pack Comfortable


Hydration bladder pack is a little small