Adidas Five Ten Kestrel Boa Review: Middle Ground

Originally released back in spring 2015, the Five Ten Kestrel has been around for nearly a decade. Having tested and reviewed the original makes that statement both bewildering and unsettling—time indeed flies. When it was first released, the Kestrel was Five Ten’s foray into light and fast MTB footwear. It was their stiffest shoe to date and quite a departure from the rest of their lineup, which has always been largely defined by their characteristic skate shoe vibe.

The Kestrel saw a couple of remodels over the preceding decade, but the most recent version, launched in April of last year, is quite a departure from the rest. Adidas claims the latest Five Ten Kestrel Boa was designed for “all-day comfort and burly all-mountain use,” which is a combination of keywords that usually pique our interest since it often translates to “might withstand the rigors of multi-day backcountry bikepacking.”

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This time, Five Ten’s goal with the Kestrel was to wedge it into the growing downcountry mountain bike category—an in-between class that often prioritizes comfort and durability over speed, eschews the matching-kit XC vibe, and focuses on design that’s lighter and more performance-oriented than products lumped into the trail or enduro segment. Five Ten’s take on this nebulous genre resulted in a new sporty-but-casual look that marries some of their trademark burly MTB construction techniques with a well-conceived design to create something that distinguishes itself from most other shoes on the XC > Trail spectrum.

Construction

The aesthetic that Adidas conjured up for the latest Five Ten Kestrel BOA also finds a pretty good middle ground. It’s undoubtedly a cycling shoe, sporting a sleek, molded look with a rounded heel cup, but it also doesn’t scream foot torture device. Still, the Kestrel Boa is built around a full-length plate design for added power transfer and stability on the pedals. Five Ten bulked it up with a few technical mountain-inspired features, including an impact-resistant toe box, chunky and relatively soft lugs, a synthetic abrasion-resistant upper that’s made in part with recycled materials, and seamless overlays.

The Five Ten Kestrel Boa comes in men’s and women’s versions, each in two color combos. The men’s fit comes in a standard Black/Gray and the more colorful Cloud White/Impact Orange. The women’s comes in the more interesting Sand Strata/Silver Violet/Acid Orange and Legend Ink/Core Black/Coral Fusion.

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The Five Ten Kestrel BOA is pretty light for a trail-oriented mountain bike shoe. It’s certainly not as svelte as most XC-race shoes, but when benchmarked against other light trail SPD shoes, it’s one of the lightest we’ve seen that still has a significantly lugged outsole. Part of this might be owed to the fact that the shank is made (at least in part) from glass fiber, which is also comprised of repurposed materials, for the record.

To put it in context, here’s a comparison chart with a few (somewhat) comparable shoes we’ve tested. Note that this isn’t an apples-to-apples comparison, since there are several sizes represented from our team of testers. Making some guesstimates and assumptions based on sizing, we think it’s one of the lightest on this list, bested only by the Specialized Recon 2.0.

• Specialized Rime 2.0 (40) 764 grams (with cleats)
• Recon 2.0 (42.5) 770 grams (with cleats)
• Giro Ventana (40) 778 grams (no cleats)
• Five Ten Kestrel BOA (43.3) 786 grams (with cleats)
• Bontrager Foray (44) 886 grams (with cleats)
• Fizik Terra Ergolace GTX (45.5) 902 grams (with cleats)
• Pearl Izumi X-Alp Summit (46) 924 grams (with cleats)
• Pearl Izumi Canyon SPD (46) 934 grams (with cleats)
• Pearl Izumi X Alp Launch (46.5) 1,130 grams (with cleats)
• Shimano GE5 (46) 1,149 grams (with cleats)

Fit

The Adidas Five Ten Kestrel BOA comes in women’s sizes 5.5-11 with half sizes and men’s sizes 6-14 with half sizes from 6.5-12.5. Five Ten’s sizing is usually a little unpredictable, but I got the size 9.5 (43.3), which were a perfect fit, and I usually wear 9.5 or 10 in US sizing and often 42.5 in EU sizing. I have relatively narrow feet, but I’m still very sensitive to having a properly sized toe box. I was quite impressed that the Kestrel BOA has plenty of space up front for my gangly digits, yet the rounded heel cup, a slight arch in the footbed, and form factor of the shoe still does a good job at locking onto my foot and preventing heel slippage—or any foot movement, for that matter.

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The Kestrel Boa has a single micro-adjustable BOA Li2 closure at the instep and a hook-and-loop strap toward the forefoot. As you can see in most of these photos, once I cinched them down, there was a lot of leftover strappage, a result of my narrow feet. Still, I found that the dial and strap combo—not to mention the tall heel tab—kept my feet locked in and comfortable, with no hot spots or pinch points. I’ve even done logged a few big all-day rides with these shoes and found them remarkably comfortable after a long grind, which was surprising.

Stiffness

As soon as I put them on for the first time, it was pretty obvious that the Kestrel Boa is built around a pedal-performance-oriented shank. It doesn’t have an assigned stiffness index number, like some other shoes, but I’d rank them between 6.5 and 7.5 on a scale from 1-10. They feel pretty firm, although not as quite as much as most XC shoes. I’d say they’re just a little stiffer than the Specialized Recon 2.0 I tested, which is another excellent “not-quite-XC” shoe.

The Kestrel Boas feel great on the pedals. I used the them with a pair of standard Shimano XT pedals, and the Kestrel’s cleat channel did a good job at “finding” the SPD interface and maintaining a secure connection with the pedal. And despite having a notably deep and narrow channel, it wasn’t abnormally difficult to unclip, either. All in all, they generally felt solid underfoot with impressive energy transfer.

Soles and Hiking

The soles also received a more agro revamp with what Five Ten calls “Pillar” tread. This knobby raised toe and heel tread is made from grippy Stealth Marathon rubber and looks like it would make the Kestrel BOA a good candidate for hike-a-bikes, or soccer, depending on who you ask. There’s also a strategically placed textured Stealth rubber instep patch for grip if you come unclipped.

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Admittedly, I typically reserve clipless shoes and pedals for drop-bar bikes. I’ve switched to flat pedals on mountain bikes 100% of the time. As such, I spent most of the testing period riding these with my Tumbleweed Stargazer, although I popped them on the Esker Hayduke LVS for a couple rides too. With that in mind, I didn’t partake in a lot of hike-a-bike epics. However, I purposefully wore them on a shoot one day where I was scurrying up and down hills, over roots and rocks, and back and forth along the trail. I also pushed a bike up a steep grades a time or two for good measure. All in all, I was pretty impressed. The Pillar tread provides superb grip on dirt and leaves. It also offers a little cushion that when paired with a slight flex at the ball/toe area provides a bit of movement and makes them surprisingly good for hiking and walking. I’d give them a solid B+ in the hike-a-bike category, with the caveat that they’re SPD shoes. They’re also generally not too bad while hanging out at the local pub after a ride. They certainly don’t have the clompy ski-boot sensation of many stiffer XC shoes.

While it may not be the optimal choice for extensive hike-a-biking, the Kestrel Boa isn’t bad, and it’s far superior to firm-soled XC shoes. Yet again, I feel like Adidas did a good job at finding a good middle ground, favoring pedal performance but not sacrificing other activities too much. The rubber soles’ grip and absorption on hard surfaces is immediately noticeable, and the toe and heel pillars provide effective traction on a variety of surfaces. I’m also happy to see another in-between shoe that doesn’t have a clunky pair plastic spikes with threaded cleats.

Durability

I haven’t put down thousands of miles on them yet, but this pair of Kestrels is holding up well after a few hundred miles. Aside from a few minor scuffs, there are no real signs of wear on them so far. If I run into any atypical durability issues down the road, I’ll be sure to update this post.

• Model/Size Tested: Five Ten Kestrel Boa, Size 9.5 US
• Actual Weight (pair with cleats): 786 grams
• Place of Manufacture: China
• Price: $230
• Manufacturer’s Details: Adidas/Five Ten

Further Reading

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