Fox Union BOA Review

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

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.

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.

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”.

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.

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.

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