Review: S/F Expandable Hip Pack is A Handy Bikepacking-Friendly Transformer

At a Glance

  • The S/F Expandable Hip Pack is a clever hybrid design that transforms from hip pack into backpack.
  • I tested it during a bikepacking trip in the desert where it was super helpful for carrying extra water.
  • The hip pack and backpack are both comfy, functional, and well-designed.
  • Though it may not be the most perfect hip pack or backpack ever made, it’s a surprisingly good combination of both. I liked it a lot.

I’ll be honest: I went out on a limb when deciding to test this expandable hip pack from the quirky collaboration between Fjällräven and Specialized. I have not been a hip pack wearer thus far, and most of the Fjällräven Specialized collaboration is, no offense meant, not quite my style. All my gear testing is done during my own personal trips, so I have a high bar for the expected usefulness of anything I decide to try.

But as a bikepacker with plenty of experience on long and varied routes, I couldn’t ignore the hip pack’s main value proposition: it transforms into a backpack when you need more space. I always bikepack with a small stuffable backpack for such occasions: long water carries, loading up at the grocery store before riding to the RV park, emergency capacity in case of a busted bag or rack. And the more I experiment with ultralight loads and technical trails, the more appealing hip packs have started to look.

So when the opportunity to test this clever transformer came along, I decided to give it a shot. As you’ll see in the rest of this review, I was pleasantly surprised. Over six days of bikepacking, mostly in the Anza Borrego Desert, it was comfortable and convenient. And when I needed to tank up with 8 liters of water… twice… the expandable backpack was clutch.

Heads up, low stock! I waited to write this review until I could test thoroughly on an actual bikepacking trip, which unfortunately took a little too long. While limited colors are still available at REI, Specialized, and Performance Bicycle, the hip pack is out of stock at Fjällräven and I’m told no more are coming. If you’re interested, get it quick!

Bikepacker rides up desert wash with yellow S/F Expandable Hip Pack in backpack mode
Heading out into the desert with 8 liters of water in relative comfort, thanks to the S/F Expandable Hip Pack.

When you buy through affiliate links in this post, I may earn a small commission. Thanks for your support! Fjällräven provided the hip pack for testing, but all words and opinions are my own.

Review Summary

Product: S/F Expandable Hip Pack

Review summary: The S/F Expandable Hip Pack might seem like it’s trying to be too many things at once, but it manages to do both its jobs quite well. It’s comfy and stable as a hip pack, roomy and practical as a backpack, and cleverly designed to transform between the two. I tested it over several days of bikepacking in the desert, mostly as expandable water capacity, and liked it more than I expected to.

Price: $120

Weight: 11.5 oz

Capacity: 4.5 liters as hip pack, 16 liters when expanded into backpack

My rating: 4.7 out of 5 stars

Shop the Expandable Hip Pack at:

What I love:

  • Hip pack is so comfy I sometimes forgot I was wearing it
  • Expandable backpack is clutch for bikepacking trips where more capacity is sometimes needed
  • Backpack is hydration bladder compatible (sleeve and hose loops)
  • Backpack is more comfortable and stable than those flimsy stuffable ones
  • Durable and high quality materials
  • Produced without PFCs

Potential drawbacks:

  • Water bottle pockets are small, I found them hard to use
  • Hip pack design is on the minimalist side, no extra pockets or compartments
  • Minor: backpack material takes up some space in the lid of the hip pack

The Use Case

In my opinion, this product’s killer use case is occasional expandable backpack space for bikepackers who like riding with a hip pack.

For context, I’ve been bikepacking with one of these stuffable backpacks for years. It disappears into my bags but is always there for me during a stupid-long water carry, the ride from the grocery store to the campsite, or as emergency capacity if a bag or rack were to fail in the middle of nowhere.

S/F Hip Pack next to stuffable backpack
The S/F Hip Pack next to a small stuffable backpack. The latter is easier to pack away into your bags when not needed, but not nearly as comfy to wear for long periods of time.

If you don’t need or want to carry a bag on your body all the time, those small stuffable backpacks are the way to go. But if you already bikepack with a hip pack or hydration pack, the S/F Expandable Hip Pack is the perfect hybrid.

Why bikepack with a hip pack? I know many people prefer to carry everything on the bike, and I generally agree with them. But there are cases where it makes sense to wear some cargo capacity: very rugged and technical terrain with lots of hike-a-bike, small cyclists with limited frame space, and full-suspension bikes, for example. In all these cases, the Expandable Hip Pack makes perfect sense.

At the risk of belaboring this point:

When to use a stuffable backpack instead of the S/F Hip Pack? When you want to wear nothing on your body most of the time. When you do occasionally load up a stuffable backpack with extra water or food, it’s not as comfortable as the S/F Hip Pack. But it does fit easily inside your bags when you’re not using it.

When to use the S/F Expandable Hip Pack instead of a stuffable backpack? When you would bikepack with a hip pack anyway. When you do occasionally load up the backpack with extra water or food, it’s more comfortable than a flimsy stuffable pack. But it won’t disappear into your bags like a stuffable backpack does; you’ll probably want to wear it all the time (or find a creative way to attach it to the outside of your bike bags).

As a Hip Pack

I don’t usually ride with a hip pack, so I was a bit hesitant to start during a multiday trip. If it was uncomfortable, I’d be stuck with it. Fortunately, I was pleasantly surprised. It felt quite stable thanks to the wide strap with side wings, didn’t bounce or rotate even on rough terrain, and didn’t cause discomfort anywhere on my body.

Close up of back of hip pack showing padding and strap
The padded back and wide hip belt contribute to this pack’s surprising comfort.

Honestly I sometimes had to look down to make sure I hadn’t left it behind, since I almost couldn’t feel it while riding. Compared to my usual hydration pack, which I use for ultralight rides where my bike needs to be lightly loaded, this was a revelation. No sweaty back or shifting shoulder straps! The S/F Expandable Hip Pack has made a hip pack convert out of me.

Bikepacker wearing yellow hip pack stops at intersection of desert dirt roads

I had wondered if the pack hitting my saddle would be a problem when dismounting, so for anyone else wondering the same thing: it wasn’t. A couple of times it was a minor annoyance while standing astride my bike, but it was easy to reach around and shift the pack out of the way.

The backpack transformation does place some constraints on the hip pack design. I’m not a hip pack connoisseur, but those who are may feel that the relatively minimalist design makes some compromises. The most obvious is that the backpack fabric, which folds up into the lid, intrudes slightly into the hip pack compartment. I found that cinching the shock cord tightly helped to keep it out of the way, and it didn’t really bother me.

View inside lid of the hip pack, with plastic bag of snacks inside

If you prefer a lot of pockets and compartments in your hip pack, this may not be for you. There are two small mesh pockets along the back panel for organization, but otherwise it’s just one big versatile compartment.

My other small gripe is with the bottle pockets. Maybe it’s because I don’t ride with small plastic bottles — my bikepacking style often requires me to tank up in larger quantities — but I found the pockets surprisingly small. It was hard to get a bottle in or out when the pack was full. I used them to carry a vending machine Gatorade at one point, which was very handy, but otherwise I just relied on the water storage already tucked in various places on my bike.

Bikepacker takes picture of her hip pack with electrolyte drink bottle in the side pocket, with vending machine in background
The side pockets are small, but came in handy for carrying this electrolyte drink on a hot day. Note: I should have looped the shock cord over the top of the bottle to keep it in place. Discovered this a few minutes later when it fell out. 🙂

While bikepacking I mainly used the S/F Hip Pack to carry my snacks. This was handy, since every time I sat down for a break I already had all my snacks within arm’s reach. I can imagine carrying all sorts of other things in it, depending on your packing arrangement: electronics, tools, lightweight layers. I couldn’t find a good way to wedge a hydration bladder into the hip pack alone, but that’s what the backpack is for (read on…).

Bikepacker holds hip pack in front to access snacks
Nice to always have snacks close at hand during breaktime.

As a Backpack

The expandable backpack is the S/F Hip Pack’s killer feature, and it’s very well executed. Though it took me a minute (see below) to figure out the transformation process, the result was solid and nicely designed.

Water sources were scarce during our bikepacking trip in the Anza Borrego Desert, so we twice found ourselves loading up with 8+ liters of water each. The Expandable Hip Pack made this easy, eliminating the struggle of awkwardly strapping more bottles all over my bike. For most of the trip I carried an empty 3 liter Platypus hydration bladder, which I filled up and carried in the Hip Pack at the start of each long water carry.

Yellow Expandable Hip Pack in backpack mode with hydration hose coming out, sitting on ground between feet
Bikepacker stands beside her bike in a desert wash, wearing yellow expandable hip pack in backpack mode

Thanks to the hip belt, the backpack is considerably more comfy and stable than a minimalist stuffable backpack. The shoulder straps are wide enough to be comfortable, even with 3 liters of water in the pack. There’s a built-in hydration sleeve (big enough for a two liter bladder, but too small for my three liters) and bladder clip, plus loops on the shoulder straps for routing the hose.

Close up of hydration bladder clip in yellow backpack
My 3 liter bladder was a bit too big for the hydration sleeve, but it still worked fine thanks to this clip that helped keep it in place.

The hip pack compartment remains when the backpack is deployed, so there’s a nice division of space. Even with the 3 liter bladder in the backpack, I could easily access my snacks down in the bottom compartment.

I originally planned to wear the backpack only as far as camp on our first long water carry, but ended up wearing it the next day too. It was comfy enough that I was in no hurry to transfer water back onto my bike as space opened up.

The Transformation

I’m not typically the type who reads the instruction manual before attempting something mechanical, so I was a bit surprised when I couldn’t immediately figure out how to transform the hip pack into a backpack. Eventually I figured out the clever trick, and after that it was super easy.

Here’s how it goes:

1) Unclip the shock cord from the tensioner on top of the lid (this is the sneaky step I missed at first) and loosen the shock cord.

Close up on hand removing shock cord from clip on top of pack

    2) Unfold the backpack material.

    Hand unfolding the backpack fabric

      3) Hook the plastic thingamajigs through the loops to create the shoulder straps.

      Close up of plastic piece passing through loop to secure shoulder strap

      And voila, ta-da, you have a backpack!

        Other Impressions

        This pack seems very high-quality in its construction, and I can envision it lasting a long time. I certainly didn’t baby it while bikepacking in the desert, yet it still looks brand new (except for a little dirt, but that’s to be expected). The logo patch is reflective, always a nice touch for those times when you find yourself on roads after dark.

        The price is on the high side compared to mainstream hip packs intended for mountain biking, such as those by Osprey and Black Diamond. But, compared to higher-end niche products designed specifically for bikepacking (Swift Industries, Wizard Words, San Util, etc) it’s on the affordable side.

        Overall it’s a clever design that’s actually quite useful in both incarnations. Sometimes gear that tries to be “too clever” ends up feeling like a gimmick that doesn’t do either job well, but I didn’t feel that way about this hip pack. It’s a legitimately useful and unique product that I’m happy to have in my gear collection.

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        About the Author

        Hi there, I’m Alissa, founder of Exploring Wild. I’ve traveled over 20,000 miles by bike and still can’t stop planning my next ride (and helping you plan yours). Pavement and panniers or singletrack and seat bag, I love it all. On my bike I feel free. Learn more about me here.

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          2 thoughts on “Review: S/F Expandable Hip Pack is A Handy Bikepacking-Friendly Transformer”

            • I guess it must have been a little bit, since it’s a backpack, but I don’t remember noticing that. The backpack fabric is light and I didn’t have it stuffed full, which probably helped – just not a big area of contact between pack and back. I’d say it felt less hot on my back than my Osprey hydration pack usually does.


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