Knack Bag Expandable Travel Backpack: The Best Carry-on Bag
Finding an expandable travel backpack that actually works for both flights and shorter trips isn’t easy. I want enough space to pack what I need without carrying a bulky backpack when I don’t need the extra room.
I’ve been traveling with my Knack expandable backpack for several years now, and it’s become one of the bags I reach for most often. I use it on almost every flight and sometimes pack it as my main bag for long weekends.
What I love most is that I can use it as a regular backpack when I don’t need much space, then expand the suitcase compartment when I need room for clothes and other travel essentials.
After years of traveling with it, here’s what I like about my Knack bag, what I think could be better, and who I think this expandable travel backpack is actually best for.
Knack provided our Series 2 bag as a sample for review. We’ve now used it for several years, and all opinions in this review are based on our own experience. This post contains affiliate links, which means we may earn a commission if you purchase through our links at no additional cost to you.
Why I Keep Using This Expandable Travel Backpack
I’ve traveled with a lot of different luggage over the years, but versatility is one of the main reasons I keep coming back to my Knack bag.
The Series 2 Expandable Knack Bag holds 24 liters normally and expands to 35 liters when I need more packing space.
That means I don’t have to carry around a huge travel backpack all the time just because I might need extra room.
I especially like having the option to expand the bag for a long weekend or when I’m carrying more on a flight, while still being able to use it as a regular backpack when I don’t need the suitcase compartment.
I often use this instead of a suitcase because I’m able to fit so much. Plus the separate expandable packing compartment is great to keep the dirty clothes separate from the clean clothes.
What Fits in My Knack Expandable Travel Backpack?
The Series 2 Medium Knack bag holds 24 liters when it’s not expanded and up to 35 liters when expanded.
But capacity numbers don’t necessarily tell you whether a backpack will work for your trip.
The expandable suitcase compartment is what makes this bag particularly useful for me. Instead of trying to shove clothing into the same compartment as my laptop, headphones, wallet, and everything else I need while flying, I can keep my clothes in a separate packing area.
I’ve been able to fit 5 shirts, 3 pants, 1 sweatshirt, bras/underwear/socks, toiletries, and a pair of shoes, with my laptop in the backpack previously! And what’s great is because it’s a backpack, it still feels comfortable on my back when it’s full.
Flying With the Knack Bag
This is where I have the most experience with my Knack bag because I use it on almost every flight.
The Series 2 Medium weighs about 3 pounds and has a padded compartment that fits a 15-inch laptop. There’s also a hidden water bottle compartment that fits my 24-ounce Hydro Flask.
I like having my travel essentials separated from my clothes because I don’t want to dig through my entire bag at the airport just to find my headphones or passport.
The front section has smaller pockets, pen holders, a key clip and a zippered pocket. I can keep things like my phone, wallet, headphones and other items I want during the flight within easy reach.
What’s nice about flying with Knack backpack, is it fits nicely under the seat. I’ve never had an issue with the size on any of the flights I’ve use it on. Plus it has trolley sleeve, so if you have a checked luggage, you can place it easily on top of that.
The Organization Is One of My Favorite Features
I’m someone who tends to pack a lot, so I appreciate having designated places for everything.
The front compartment is particularly useful for the smaller things I want to access quickly instead of letting them disappear into the bottom of my backpack.
The main compartment also has two mesh pockets and a fleece-lined pocket. There’s a separate padded laptop compartment, hidden water bottle pocket and another hidden zippered compartment.
For me, that organization is one of the biggest advantages of the Knack over using a traditional backpack as a carry-on.
Instead of opening one giant compartment every time I need something, I can keep my travel essentials separate from the clothing I’ve packed in the expandable section.
Is the Knack Bag Comfortable When It’s Full?
An expandable backpack isn’t particularly useful if expanding it makes it miserable to carry.
I tend to pack a lot, but I’ve found the Knack comfortable to carry even when I have quite a bit inside. The Series 2 has padded foam shoulder straps, which helps when I’m walking through airports with a fully packed bag.
The shoulder straps can also be tucked away when you don’t want to wear it as a backpack. With handles on the top and side, I can carry it more like a duffel bag when that makes more sense.
I will admit, if you have a long walk through the airport, the backpack can get a little heavy if it’s full, but that’s true for any full bag. I really think the backpack is pretty comfortable, and have only noticed that when I’ve been traveling for a long time, and not able to take the backpack off.
What I Don’t Like About the Knack Travel Backpack
The bag is comfortable when it’s full, but there is a limit. Once I pack the expandable compartment completely, add my laptop and fill my water bottle, I start to notice the weight on longer walks through the airport. I wouldn’t want to spend an entire day sightseeing with it packed that heavily, but for getting through the airport and to my hotel, it’s comfortable.
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Who Is This Expandable Travel Backpack Best For?
After several years of using mine, I think the Knack makes the most sense for travelers who want one backpack that can serve several purposes.
I’d particularly consider it if you:
- Fly frequently and want an organized carry-on backpack. This is where I get the most use out of my Knack. I take it on almost every flight, and I love being able to keep my laptop and things I need during the flight separate from my clothes.
- Take short trips where you don’t necessarily want a suitcase. I’ve used my Knack for long weekends when I don’t want to deal with rolling luggage. Expanding the main compartment gives me enough room for clothes while still keeping everything in one bag.
- Travel with a laptop or other electronics. The separate laptop compartment means I don’t have to dig through my clothes to get my laptop out, which is especially helpful when I’m going through airport security or want it during a flight.
- Love having a place for everything. If you’re the kind of person who hates throwing everything into one giant backpack compartment, this is one of the Knack’s biggest strengths. I use the different compartments to keep my smaller travel essentials separate instead of digging around for them.
- Want one bag that can serve multiple purposes. This is probably my favorite thing about the Knack. I can keep it compact when I don’t need much space and expand it when I’m packing for a longer trip.
I wouldn’t automatically recommend it to everyone, though.
Skip this bag if you:
- Skip it if you’re a serious over-packer. I tend to pack a lot myself, and the expandable compartment gives me enough extra room for most trips. But if you’re someone who needs multiple pairs of shoes, lots of outfit options, or a large toiletry bag, the 35L capacity may feel limiting.
- Don’t like carrying weight on your back. Even though I find the padded straps comfortable, this is still a backpack. Once it’s loaded with clothes, a laptop, water bottle, and everything else, you’re going to feel that weight.
- Prefer rolling luggage. If your priority is getting through an airport without carrying your luggage, an expandable backpack probably isn’t the right style of carry-on for you.
- Need maximum carry-on space. The advantage of the Knack is its ability to transition between a regular backpack and an expanded travel bag. If your only concern is fitting the maximum amount possible into a carry-on, you may be better served by a traditional carry-on suitcase.
Is the Knack Expandable Travel Backpack Worth It?
For me, yes.
The best evidence I can give isn’t the list of features on Knack’s website. It’s that I’ve had this bag for several years, traveled with it repeatedly, and I still reach for it for almost every flight.
That’s ultimately what I want from travel gear.
I don’t want something that sounds great when I first get it and then sits forgotten in a closet. I want gear that makes traveling easier enough that I keep choosing it trip after trip.
The expandable design gives me extra packing space when I need it without making me carry a larger backpack all the time. I also love having separate areas for my clothes, laptop and the smaller things I want accessible while flying.
If you’re looking for an expandable travel backpack that can transition from a regular backpack to a carry-on or weekend bag, the Knack is one I’d recommend based on my own long-term experience with it.
[Check the current Knack bags and choose the size that works best for your travels.]
