Fox Union BOA Flat review – high-performance flat pedal shoes with a high price tag

Fox unveiled its original laced Union Flat shoes last year and followed up with a canvas version and the BOA-equipped model. I was impressed with the originals and gave them 4.5 stars out of 5 in my Fox Union Flat review, rating them as some of the best mountain biking flat shoes you can buy. So could replacing the laces with a BOA fastening system improve the already excellent shoes? I've been testing the Fox Union BOA Flat shoes over the past six months to find out.

Design and specification

Aside from the twin BOA dials that have replaced the laces of the original shoes, the Union BOA Flats are almost identical to the laced versions. They have the same impressively grippy Ultrac sole, the same midsole, and very similar one-piece uppers. Like the laced model, they're made with fully synthetic materials too.

There are a couple of small differences though – you get tune-able arch support with two inserts of different thicknesses that sit beneath the insole. Also, the toe area has been tweaked with fewer ventilation holes and a bit more reinforcement on the crank side.

The BOA-equipped Union Flats are slightly heavier than the laced versions (426g vs 412 per shoe), but only the most miserly gram counters will care. At 852g per pair in a size 44, the Union BOA Flats are heavier than other leading flat MTB shoes though. Five Ten Freerider Pros weigh 748g and Specialized's 2FO Roost Canvas comes in at 728g, both are also size 44.

Performance

I've been riding in the Union BOA Flats for the past six months in all kinds of weather and trail conditions. Like the original versions, pedal grip proved to be excellent no matter how bad the conditions got, and walking grip was pretty good too.

There's a big difference in how the shoes feel compared to the laced versions though. The twin BOA fastenings allow you to cinch up the uppers tighter around your feet, while a smaller opening above the tongue means there's more material wrapped around your feet too. The result is a much stiffer and more secure feel that's more akin to a clipless shoe than a regular flat pedal model. A tighter fitting upper means there's less give in the sole, this gives a stiffer pedaling feel than the laced version but reduces pedal feedback a touch too.

Doing away with water-absorbing laces, having a slimmer opening in the shoe, and fewer ventilation holes on the crank sides mean better protection against splashes and spray. After riding wet trails, my feet are noticeably drier in the BOA Flats compared to the laced versions and other similar rivals.

After many months of testing, the BOA Flats are still in decent shape. There's less creasing behind the toe box compared to the laced model, and the soles have not cut up too much. Yes, there are cuts and knicks from pedal pins, but there's no sign of holes in high wear areas as yet.

The only real downside of the BOAs is that the stiffer feel means they are not quite as comfortable as the laced shoes. Also, when walking in the BOA Flats there was some chafing around my ankles from the tighter fit. This may not affect everyone, but I didn't have this issue with the lace-up Unions Flats.

Verdict

In terms of performance, the Fox Union BOA Flats are right up there with the top-rated flat pedal shoes around. Grip is excellent, they provide a good pedaling platform without overly dulling feel, and they keep the elements at bay better than most regular shoes. When it comes to the price though, the BOA wires add a hefty chunk to the RRP as the shoes cost a third more than the lace-up versions. They're pricey compared to most of the competition too.

Those prepared to shell out will be getting an excellent pair of flat pedal shoes, and handily, you can usually find the Union BOA Flats at a discounted price.

Tech specs: Fox Union BOA Flat

• Price: $224.95 / £209.99 / €229
• Sizing: 37 to 47 EU
• Weight: 852g (size 44 EU tested)
• Colors: Gray, Black, Vintage White
• Materials: TPU, EVA, rubber