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Fox Union BOA Review

High-end gravity shoes for enduro and downhill riders who value a relatively low weight and refined design
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Fox Union BOA Review (The Fox Union BOA are sleek gravity shoes that are happy to do a bit of everything.)
The Fox Union BOA are sleek gravity shoes that are happy to do a bit of everything.
Credit: Pat Donahue
Price:  $250 List
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Manufacturer:   Fox
By Pat Donahue ⋅ Senior Review Editor  ⋅  Apr 20, 2023
80
OVERALL
SCORE


RANKED
#11 of 20
  • Comfort - 25% 8.0
  • Traction and Walkability - 25% 8.0
  • Power Transfer - 20% 8.0
  • Weight - 15% 8.0
  • Durability - 15% 8.0

Our Verdict

The Fox Union BOA are an outstanding choice for enduro racers or aggressive riders. The Union BOA is Fox's first entry into the shoe market and they knocked it out of the park. This shoe delivers a nice amount of power transfer, a comfortable fit, and a very long cleat channel allowing nearly every rider to find optimal cleat placement. Oh yeah, the Union BOAs achieve all of this while retaining a very reasonable weight. There is a whole lot to like about these shoes and while they aren't cheap, they should be a favorite among the downhill and enduro crowd. See it rated versus top competitors in our mountain bike shoes review.
REASONS TO BUY
Light for a gravity shoe
Long cleat channel
Clean looks
REASONS TO AVOID
Expensive
Could be problematic for riders with wide feet

Compare to Similar Products

 
fox union boa
This Product
Fox Union BOA
Awards Top Pick Award
Best Downhill Shoe
Editors' Choice Award
Best Overall Trail Riding Shoe
Editors' Choice Award
Best Overall Cross Country Shoe
Best Buy Award
Best Bang for the Buck Cross Country Shoe
Best Buy Award
Best Bang for Your Buck All-Mountain/Trail Shoe
Price $199.99 at Amazon
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$220 List
$220.00 at Backcountry
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Bottom Line Dialed downhill and enduro shoes that pair comfort and performance with a low weightA unique design and a great blend of on and off-the-bike performance make this a versatile trail and all-mountain shoeLightweight, stiff, and comfortable, this shoe is one of our favoritesAn XC/trail riding shoe that combines high performance with affordabilityLightweight with good power transfer and walkability, these are a reasonably priced trail riding shoe with casual styling
Rating Categories Fox Union BOA Shimano ME7 Giro Empire VR90 Scott MTB Team Boa Specialized 2FO Roo...
Comfort (25%)
8.0
9.0
9.0
9.0
7.0
Traction and Walkability (25%)
8.0
9.0
6.0
6.0
9.0
Power Transfer (20%)
8.0
8.0
8.0
9.0
7.0
Weight (15%)
8.0
8.0
9.0
10.0
10.0
Durability (15%)
8.0
9.0
9.0
7.0
7.0
Specs Fox Union BOA Shimano ME7 Giro Empire VR90 Scott MTB Team Boa Specialized 2FO Roo...
Closure Dual Boa Li2 dials Speed lacing system with cover and ratchting upper bucckle Laces Boa iP-1 dial, plus velcro strap Laces
Measured Weight (per shoe) 458 grams 415 grams 388 grams 359 grams 375 grams
Size Tested 11 44 45 44 43.5
Width Options Regular Regular and Wide Regular and High Volume(HV) Regular Regular
Upper Material One-piece synthetic, weather-resistant welded construction Synthetic Leather Microfiber Synthetic Polyurethane, 3D Airmesh Synthetic Leather and Textile
Footbed Customizeable arch support Shimano Pedaling Dynamics insole molded EVA footbed ErgoLogic Specialized Body Geometry
Midsole Tuned EVA with reinforced nylon shank Carbon Fiber composite "TORBAL" midsole Easton EC90 Carbon Fiber Nylon/Glass Fiber Composite Stiff Lollipop nylon composite plate
Outsole Ultratac rubber compound Michelin OCX3 dual-density Vibram Mont Molded Rubber High Traction Lugged Outsole, Mid-Foot Scuff Guard, Accomodates Steel Toe Spikes StickiRubber SlipNot FG

Our Analysis and Test Results

The Union BOA earned a Top Pick for Best Downhill Shoe. There wasn't a single performance metric that blew our minds. These shoes offer a very nice level of comfort and impressive stiffness. They give the rider power transfer and provide solid traction off of the bike. While there wasn't one single metric that jumped off the page, we were very impressed with the complete package. In addition, these shoes are significantly lighter compared to other top-gravity shoes while.

Performance Comparison


fox union boa - these shoes should work great for most feet. boa dials help you...
These shoes should work great for most feet. BOA dials help you fine-tune the fit/tension.
Credit: Pat Donahue

Comfort


Our size 11 test shoes fit true to size. Right out of the box, they were quite comfortable. Riders with particularly wide feet might want to consider trying these shoes on prior to purchase or ensuring the online retailer has a good return policy. They are not narrow, but average in terms of width. We are simply commenting that we can see a situation where riders with wide feet might not get along with these shoes.


They feel padded and reasonably plush without the bulk of some other gravity shoes. Considering how sleek these shoes appear, they feel well-padded and protective.

The shoes are secured by a BOA Li2 system. There are two BOA dials on each shoe to help fine-tune the fit. The dials are easy to use and feel like they have small increments of adjustment, meaning you have to rotate the dial quite a bit to tighten the shoes significantly. It also means it is easy to just use a couple of clicks here and there to really hone in on a perfect fit. This system works well and looks extremely clean. There was a time when many users were a little weary of BOA systems on shoes due to some reliability concerns. That being said, they seem to have sorted out many of these issues in recent years.

On the trail, these shoes offered all-day comfort. We would have no problem wearing these on any ride, from an all-day bike park mission to a long backcountry adventure. Bouncing down rough trails our feet didn't get beat up thanks to the EVA midsole. These shoes have some ventilation dots on top of the toe box and on the inside and outside of the midsection of the shoe. It is difficult to tell exactly how well these ventilation systems work. We can say that the lower weight and lack of excessive padding allow these shoes to feel reasonably cool and dry out quickly if they get wet.

fox union boa - traction/walkability is solid. these shoes feature an enormous cleat...
Traction/walkability is solid. These shoes feature an enormous cleat channel to fine-tune cleat position.
Credit: Pat Donahue

Traction and Walkability


For many riders, a mountain bike ride can involve a bit of walking. Whether this is a hike-a-bike up an impossible climb or simply navigating around a downed tree, the Union BOA offers solid traction.


The Ultratac sole is covered with traction blocks of varying shapes. Some blocks are rectangular, while others are some sort of blend of a diamond and hexagon. The blocks are raised approximately 2mm off of the sole. When hiking up a steep pitch, these shoes offer a nice amount of traction. We tested these shoes in all conditions, from frozen soil to very wet conditions and even a bit of dust. They offer plenty of grip.

When walking in cycling shoes, you are fighting against the stiff sole and shank. Typically, the stiffer the shoe, the tougher they can be to walk in. The Union BOA shoes offer a decent feel. Since these aren't ultra-stiff cross-country shoes, they offer decent walking performance. Still, we wouldn't want to walk miles upon miles in these bad boys.

fox union boa - while these are definitely gravity/downhill shoes, they are...
While these are definitely gravity/downhill shoes, they are reasonably light and can work very well for aggressive trail riders.
Credit: Pat Donahue

Power Transfer


The Union BOA offers excellent power transfer and stiffness. There is no mistaking this gravity shoe for a carbon-soled cross-country shoe, but it offers plenty of rigidity to allow for excellent power transfer and feel on the pedals.


This shoe runs a lightweight nylon shank paired with an exceptionally long cleat channel. We can confidently say that this is among the longest channels we have seen on a shoe to date. What does that mean? In recent years there has been a desire among enduro and gravity riders to push their cleats back (rearward) as far as possible to achieve better control of the bike. The super-long channel allows for such positioning while also allowing riders who prioritize pedaling power to move the cleat forward. In fact, these shoes have lines to help guide your cleat placement with an arrow pointing toward the toe for “power” and rearward for “control”.

fox union boa - these shoes are plenty stiff for solid power-transfer while...
These shoes are plenty stiff for solid power-transfer while retaining an OK feel off the bike.
Credit: Pat Donahue

On the trail, the Fox shoes feel wonderful. Standing up to smash the pedals results in excellent power transfer. It feels like there is no energy lost into a flexy sole. Another bonus of the stiff sole is it really communicates your position on the pedal. It makes it easier to find the right place on the pedal to engage the clip mechanism with your cleat.

Weight


The Fox shoes really impressed us with their reasonable weight. Our size 11 test shoes hit the scales at 458 grams per shoe. To be clear, these are gravity or enduro shoes, and most of these riders aren't going to be concerned about a few grams here and there. That said, the Union BOA are lighter than just about all of the gravity shoes we have tested…in some cases, by close to 100 grams. This is significant. It is very important to note that we tested a size 11 pair of these shoes. Other downhill/gravity listed on our charts were tested in a smaller size 10. This makes the lower weight even more impressive.


On the trail, the reasonable weight was noticeable. Our tester owns a pair of shoes that are roughly 100 grams heavier than the Union BOA. Upon sliding into these shoes, the reduced weight was absolutely noticeable.

fox union boa - a welded toe and heel enhance durability. historically, boa dials...
A welded toe and heel enhance durability. Historically, BOA dials have lacked reliability. That said, we have seen a huge improvement in recent years.
Credit: Pat Donahue

Durability


Throughout testing, we observed no areas of premature wear or material breakdown. These aggressive shoes feature a welded heel cup and toe cap meaning there are no stitches in these high-wear areas. The stitching that runs along the middle portion of the shoe is intact. In addition, the soles show no sign of significant wear.


The main reason these shoes got docked in the durability metric is the presence of the BOA Li2 system. While we absolutely love the clean looks and functionality of BOA systems, they are inherently more complex than a lace system. BOA systems have a checkered history, and while significant improvements have been made, it is not fun when they fail. Simply put, the classic lace design will always be more reliable than a more complicated system. Again, we didn't experience any issues with these shoes, but we have had multiple BOA systems fail in the past, and it still haunts us.

Should You Buy the Fox Union BOA?


The Fox Union BOA is for the true gravity enthusiast. Our team found it to be reasonably versatile for most types of mountain bike riding, but its underlying design trends toward aggressive riding. If you want a lightweight descent shoe with a long cleat channel and a no-brainer closure, this is the one.

fox union boa - we love the fox union shoes for all gravity-fed endeavors.
We love the Fox Union shoes for all gravity-fed endeavors.
Credit: Pat Donahue

What Other Mountain Bike Shoes Should You Consider?


The Specialized 2FO Roost Clip is a strong choice if you want an all-trail shoe that won't cost an arm and a leg. This model has a casual look, has great power transfer, and it's light. If you're looking for a downhill shoe that's even burlier and more durable than the Fox Union BOA, check out the Ride Concepts Tallac Clip, which offers ample padding and comfort.

Pat Donahue