Mystery Ranch Urban Assault 18, as a Kids Backpack

If your kid is taller, then this is the backpack to get them. It’s very good.

I’ve talked about the Mystery Ranch Urban Assault 21 before (a couple of times) — I love the bag. But there’s two other offerings of this bag: the Urban Assault 24 (which I don’t like the look and design of so I won’t try) and the Urban Assault 18. The 18 is the same as the 21, cut down in size to fit a smaller frame.

Mystery Ranch achieves this by only slightly trimming the width and depth of the bag, and wisely trimming the height from 20.25” in the Urban Assault 21, to 18.5” in the Urban Assault 18. The end result is a bag which has almost the same capacity and dimensions of the 21L, but is shorter to help fit shorter frames. I bought two of these, one for each of my daughters. They love them, even if they are still a little large on them.


The previous backpacks my kids were using was the GORUCK Echo/KR1s which are 16.5” tall. They are also wide and have classic GORUCK shoulder straps. So while the bags fit them great vertically they struggled with the oversized shoulder straps at times being near the outside of their shoulders, as well as with the width being wider than they are/were.

UA18 left, UA21 right.

Instead of chopping height by shortening the bottom, they bring it out of the top, which means the UA18 straps secure right at the top of the bag, no need for load lifters. Smart.

The Urban Assault 18 flips that around. The bags are narrow enough they feel like they fit their backs, but the added two inches of height does show on them. Not enough to elicit complaints, but visually they look a little big for the kids, especially my youngest. I would say that the minimum height for this to fit a kid well is somewhere around the 50” tall mark, which means it’s a slightly older kid.


Comfort was the big driving factor for buying these bags, as neither kid wanted to wear their GORUCK bags as a day hiking backpack during the lockdown. After the first trip out with the Urban Assault 18, my oldest remarked: “best one yet dad”. Which I guess is a testament to how many backpacks they have tried for me, but also she was very happy with the comfort of this bag. “The straps feel really nice, they are so soft.”

She’s 9, and 56” tall or so.

They both love the fit and comfort of these bags, and I have to agree with them: the Urban Assault 18 has a great shoulder strap setup even for someone like me who is 6’-3” tall. Though I do find the bags to be a bit small for me, not so much so that I can’t carry them if/when needed. Aces.

I’m much older, 6’-3” tall.

This is just a very nicely comfortable bag, whether it is loaded up, or nearly empty. My kids wear it without complaint, and are pretty happy about it. Both have GORUCK bags, and both opt for this Urban Assault 18 any time they are asked to get a backpack to take with them.

So while I may think they visually look a little large on the kids, neither of the kids seem bothered by it in the slightest. My youngest wears it very lose such that it hangs very low, and she said “it’s best like this” — ok kid.

Two Modifications

There’s two modifications I made. One is a must, and the other is 50/50 you need to do it.

  1. You need something to hold the dangling webbing after you tighten the backpack — they are very long and you’ll likely be cinching the straps all the way down as it is for kids. I like elastic webbing keepers as you can put them on the main strap so they never are at risk of falling off. Not that kids would ever lose something like that. From there just roll up the webbing and shove it in the elastic loop. Out of the way and good to go.
  2. There’s a problem with a lot of Mystery Ranch tri-zip bags where the zippers all meet. At this point the vertical zipper can slightly bind when trying to move past this area during the opening motion. It doesn’t stick as much as it just slightly binds and disrupts a smooth opening. This happens in about half the Mystery Ranch bags I try — certainly not all (even within the same product family). Usually it’s nothing to worry about, certainly not for adults. But if your kids struggle, then a needle and thread can remedy this easily. Basically you sew the incoming zipper end so it is folded back and out of the way. Works like a charm. I’ll post a few pictures below for you.


This bag is a smaller Urban Assault 21, but it doesn’t come with many of the downsides that many ‘smaller version’ bags do. So you can take most of the Urban Assault 21 and directly use that as a comp of the 18. Yes, the straps are a little more narrow, but the proportions are so well scaled down that the bag still feels good.

This isn’t the best for the shorter kids out there, as I don’t think I would try it if they are under 50” in height. But once they start getting taller, this bag is fantastic. That said, it’s not that shorter kids can’t use it, it will hang down farther, and depending on your kid that may or may not bother them.

You can find these on sale from about $66-95 pretty regularly, but even at the full $125 they are built really well. And of all the kid focused bags I’ve tested, these are the ones my kids find comfortable and easy to use, while still being durable and well made.

I’m a big fan. Find them here.

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