Reviews You Can Rely On

Luna Oso Flaco Winged Review

For those curious about minimalist running, this sandal offers superior traction and secure straps that will keep you comfortable on the trail
luna oso flaco winged sandals women review
Credit: Luna
Top Pick Award
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Price:  $110 List | $110.00 at Amazon
Pros:  Great traction, secure straps, lightweight
Cons:  Uncomfortable, difficult to adjust, questionably stylish
Manufacturer:   Luna
By Joanna Trieger ⋅ Review Editor  ⋅  Mar 23, 2022
Our Editors independently research, test, and rate the best products. We only make money if you purchase a product through our links, and we never accept free products from manufacturers. Learn more
70
OVERALL
SCORE
  • Comfort - 20% 5.0
  • Traction - 20% 9.0
  • Adjustability - 20% 7.0
  • Stability - 15% 8.0
  • Versatility - 15% 6.0
  • Style - 10% 7.0

Our Verdict

If you've been itching to get into minimalist women's trail running shoes but weren't sure where to start, we've got you: pick up a pair of the Luna Oso Flaco Winged. This pared-down, thin-soled model provides enough protection for comfortable trail running while giving the wearer a real sense of the ground beneath her feet. After dozens of miles loping up and down rocky single track and crashing through streams, we can report that the Oso Flaco really holds up, earning it our Top Pick for Minimalist Trail Runners Award. Beyond running, though, this model isn't one of the best women's sandals for comfort, versatility, and style, so we don't recommend it as an all-around pick.

Editor's Note: This women's sandals review now includes more information on the sandals we prefer and why. The update happened on March 23, 2022.

Our Analysis and Test Results

Have you read the book Born to Run? Wondering what Barefoot Ted has been up to since his foray into the Copper Canyons? Well, wonder no more: we're here to report that Ted put his wacky brain to work creating a minimalist footwear line, Luna Sandals, so the rest of us can experience the joys of running free. Intrigued, we added the Luna Oso Flaco Winged to our testing lineup to see how it stacked up. While this model isn't comfortable, versatile, or stylish enough to get an all-around thumbs up, its outstanding traction and secure strap system make it an excellent introduction to barefoot trail running. Read on to see if you're ready to leap, but be warned: you may never go back!

Performance Comparison


luna oso flaco winged sandals women review - the lunas in their natural environment: the mountains!
The Lunas in their natural environment: the mountains!
Credit: Joanna Trieger

Comfort


This extremely minimalist sandal doesn't put a lot of material between you and the ground, so it's not the most comfortable model we tested.


The Oso Flaco is meant to mimic barefoot running, so it doesn't have many features we'd describe as "comfortable." Its sole is thin and flexible, so you feel every lump and bump in the ground as you walk or run. Its straps are also thinner than most of the other models we tested, and they need to be tightened significantly to achieve a secure fit, so they tend to dig into the skin. The semi-firm rubber elements on the sides of the foot that the straps pass through are fixed in place, so if they happen to hit your foot in an uncomfortable spot — as they did for our lead tester — you're in for an uncomfortable ride.

luna oso flaco winged sandals women review - this model's thin straps and fixed-in-place side-foot attachment...
This model's thin straps and fixed-in-place side-foot attachment points make it a less-than-comfortable hiking option.
Credit: Joanna Trieger

This model truly is designed for running, and we found that something about the running motion made the Oso Flaco Winged feel more comfortable. When running, the foot tends to move back against the heel strap, which distributes the pressure better between the thin straps and aligns the foot better with the rubber elements that hold the straps. So, surprisingly, this generally uncomfortable model becomes one of the most comfortable while running.

One major point of discomfort we have to mention: the lugs at the sides of the out-of-the-box Lunas are so sharp that if you happen to catch your opposite ankle with the side of your sandal mid-stride, you may be in for a nasty cut. Help us out and file down those side lugs a touch, Luna!

luna oso flaco winged sandals women review - yikes! our tester sustains a small flesh wound after brushing her...
Yikes! Our tester sustains a small flesh wound after brushing her ankle with the Luna's sharp lugs on the trail.
Credit: Joanna Trieger

Traction


Designed for steep, uneven trails and river crossings, the Oso Flaco excels in this category.


The Oso Flaco has deep, strategically placed lugs and a super-thin, flexible sole. This allows it to conform to pretty much any trail feature with an insane monkey grip. We tested this model on steep, loose dirt, slick rock, cobbled trails, and river crossings, and it performs admirably in each of these scenarios.

luna oso flaco winged sandals women review - this is one of the most tractioned models we tested. we trust the...
This is one of the most tractioned models we tested. We trust the Luna's deep-lugged Vibram sole on virtually any surface.
Credit: Joanna Trieger

This model is especially excellent in water because the thin sole allows you to use your toes to grip rocks for extra stability. On the downside, the footbed gets pretty slippery when it's wet. When you emerge from the river crossing and continue down the trail, you'll slosh around in the sandal for a bit until things dry out.

luna oso flaco winged sandals women review - the oso flaco's outsole is outstanding in watery environments, but...
The Oso Flaco's outsole is outstanding in watery environments, but unfortunately, the footbed gets slippery when wet.
Credit: Joanna Trieger

Adjustability


With one flow-through strap and several adjustment points, it's possible to dial in the fit of the Oso Flaco, but doing so requires trial-and-error, and on-the-go adjustments are tough. This model scored in the middle of the pack in this category.


The Oso Flaco has a single flow-through strap that starts between the toes, loops around the back of the foot with two rubber elements on the sides of the foot as guides, and then reattaches to itself with an adjustable buckle on the top of the foot. This means it's possible to adjust the length of the heel strap by pulling more or less strap through the side-foot elements. The positioning of the top-foot buckle can be changed by sliding it back and forth along the strap, and the tightness of the whole sandal is adjusted by cranking down on the cross strap.

luna oso flaco winged sandals women review - adjusting the lunas on the fly using these top-foot buckles is...
Adjusting the Lunas on the fly using these top-foot buckles is relatively easy. Dialing in the overall fit right out of the box takes some trial and error.
Credit: Joanna Trieger

If this sounds like a pain, that's because it is. It's possible to dial in the fit of the Oso Flaco, but it takes trial-and-error, and each adjustment to the heel strap necessitates removing the sandal. The rubber elements and the top-foot buckle are stiff, so pulling the strap through takes force. On the upside, once the sandal is adjusted to your foot, the straps tend to stay put, so you'll only have to do this once. You can easily make the whole sandal tighter or looser during runs by tightening or loosening the cross strap.

Unfortunately, the rubber elements on the side of the feet are fixed in place, so if they don't fit your foot's anatomy, there's not much you can do about it. We'd love this sandal more if these could be angled to fit a wider variety of foot shapes.

Stability


With a supple sole and secure straps, the Oso Flaco feels stable on a wide variety of terrains.


The sole of the Oso Flaco is extremely flexible, contours to the terrain, and helps the wearer feel stable. The footbed is wide, but the straps are secure, so the foot stays centered in place. While running, we found this model to be more stabilizing than even our thick-soled, crazy-lugged trail shoes.

luna oso flaco winged sandals women review - the sole of this model is thin enough that it can contour around...
The sole of this model is thin enough that it can contour around rocks, which adds a feeling of stability on the run.
Credit: Joanna Trieger

We can't emphasize enough that the sole of the Oso Flaco is thin. While wearing a pack or otherwise carrying a heavy load, it can feel unsupportive, almost like you're walking…well, barefoot. If you're looking for a model that will feel cushy and supportive while you're carrying a pack, consider something with a thicker sole.

luna oso flaco winged sandals women review - two approaches to stability: the thin-soled luna, left, allows the...
Two approaches to stability: The thin-soled Luna, left, allows the wearer to contour to uneven terrain, while the Bedrock, right, absorbs the lumps and bumps of the trail.
Credit: Joanna Trieger

Versatility


This sandal is great for running! We'd also recommend it for running, and while we're at it, have we mentioned running? We love the performance of the Oso Flaco as a trail runner, but it's not the sandal we choose for most other applications.


Our first impressions of the Oso Flaco weren't great. This model is not super-comfortable out of the box, and after an initial hike, we were ready to relegate these to the "quirk over quality" pile. But since these are clearly meant to be trail runners, we thought we should at least try to take them for a spin…and just like that, our lead tester was hooked. This sandal opens up and embraces the foot while running in a way it doesn't seem to do on hikes or jaunts around town. So if you've been curious about minimalist/sandal running, we'd strongly recommend giving these a try.

luna oso flaco winged sandals women review - running in sandals allows your toes to spread out and encourages a...
Running in sandals allows your toes to spread out and encourages a forefoot strike, which can improve posture. Our lead tester got hooked on running in Lunas after just one run.
Credit: Joanna Trieger

But for most other applications, the Oso Flaco falls short. It's not comfortable enough to be a regular hiker, it's not supportive enough for backpacking, and its soles are too flexible for all but the most casual bike rides. Look elsewhere if you're looking for the one sandal to rule them all.

luna oso flaco winged sandals women review - the oso flaco is flexible and comfortable enough to wear during your...
The Oso Flaco is flexible and comfortable enough to wear during your post-run stretch routine. Canine assistants not included!
Credit: Joanna Trieger

Style


With its unique shape and technical feel, the Oso Flaco either suits your taste, or it doesn't.


No one will mistake this for a fashion sandal: the Oso Flaco looks like outdoor gear enthusiasts designed it for use on the trails. Our testers and the friends and family we surveyed had mixed reactions to the look of this model, but feelings were generally positive, especially among trail-lovers. The Oso makes a unique accompaniment to a casual jeans outfit, but it would probably look out of place with anything dressier.

luna oso flaco winged sandals women review - this model has a decidedly technical feel. we show them here covered...
This model has a decidedly technical feel. We show them here covered in mud, as befits a great trail running shoe.
Credit: Joanna Trieger

This model comes in several patterns and solid black, so you can coordinate with your favorite trail running gear if you're so inclined.

Should You Buy the Luna Oso Flaco Winged?


As our Top Pick for Minimalist Trail Runners, the Luna Oso Flaco Winged is a unique option that offers enough protection to keep you comfortable on the run while still letting you feel the earth beneath your feet. If you want a single sandal that will take you from trail to bike to bar patio, this may not be it, but if minimalist running is your main goal, we think you should give this model a try. A pair of dedicated trail running shoes will generally cost you a good deal more than these sandals, so if you're considering this model to replace or extend the life of your favorite traditional trail model, it's a good deal. Based on the extremely minimal wear and tear we observed after about 65 miles of trail running and dozens of miles of other activities, we think this pair will last well beyond the 500 miles we'd expect from a regular trail trainer. We personally don't recommend the Oso Flaco for much beyond trail running, so if you're looking for an all-around sandal, this may not be a good value. That said, there are many folks that do wear these for hiking and around town. As with anything, it all depends on your anatomy and personal preferences. Because of the oddities of this sandal, however, it's one we recommend trying on before buying if you can.

luna oso flaco winged sandals women review - great traction, unique design, solid stability...will these lunas...
Great traction, unique design, solid stability...will these Lunas lure you into minimalist running?
Credit: Joanna Trieger

What Other Sandal Should You Consider?


If you love the idea of a thong adventure sandal but long for something a little beefier, the Bedrock Cairn Adventure - Women's is a higher-ranking option that often costs less. This sandal has a thicker sole and offers more comfort and adjustability. It might not be as runnable as the Oso, but it scored higher in our tests for traction and versatility. If you love the idea of the style but want a more contoured footbed, the Bedrock Cairn 3D PRO II Adventure provides more support and cushion without sacrificing functional performance.

Joanna Trieger
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