If you’re a downhill mountain bike racer or a fan of the sport, you’ll know that the suspension battle is currently dominated by two main players – the Rockshox Boxxer and the FOX Racing Shox 40. Personally, I’ve always been a Boxxer guy. I purchased my first Boxxer in 2004, and have easily spent hundreds of hours aboard each generation since. From the underwhelming and unreliable HC2 versions through today’s excellent Charger damper-equipped models, my allegiance has been stubbornly steadfast.
However, when FOX offered me the chance to spend the past season aboard an early release 2016 FLOAT 40, I couldn’t pass it up. My experience with the FOX 36 renewed my interest in FOX’s fork offerings, and I don’t claim to be unbiased in saying that throughout the season I’ve spent aboard the latest FLOAT 40, it’s been nothing short of outstanding.
The author racing Utah State Downhill Series Finals at Brian Head Resort, Utah
Despite some significant changes since its introduction, the appearance of the 40 is much as it was a decade ago. Of course, this iteration has had every last gram of unnecessary material removed from the lowers and the crowns, which brings the fork’s weight a few grams under that of its closest competitor, the air-sprung Boxxer World Cup. Unlike the Boxxer, the 40 uses pinch bolts to secure both sides of the 20mm thru axle, which is partially responsible for the 40’s superior stiffness. The pinch bolts thread into a replaceable steel insert rather than directly into the lowers, which allows for easy replacement in the unlikely event that you strip the threads.
The high-volume air spring allows the fork to be run at comparatively low pressures, which enhances the longevity of the seals and reduces friction within the spring. Functionally, this version is a significant upgrade over the earlier FLOAT springs, which employed a coil negative spring. While the earlier design only worked ideally within a limited range of pressures, the new FLOAT spring has a self-adjusting air negative spring. This keeps travel smooth and supportive over the entire range of possible spring rates, and saves a handful of grams as well. On the damper side, the sealed FIT RC2 unit is fairly user-friendly in terms of adjustment, with high-speed compression (HSC) and low-speed compression (LSC) being independently adjustable. Critics of the 40 have focused on its appetite for maintenance, but the 2016 model is rated to much longer service intervals, bringing it into line with similar race-grade forks. That’s a factor that those of us without personal mechanics will certainly appreciate.
The author skipping the rut at Canyons Bike Park, Park City, Utah
The test spanned eight months and half a dozen races without a rebuild, meaning that the fork is long since overdue for service. This deliberate neglect was intended to assess the fork’s durability, and while it resulted in loss of a perceivable degree of small-bump compliance toward the season’s end, its ride characteristics remained acceptable through the end of the test period. Impressively, this neglect hasn’t resulted in a failure of any kind—a testament to the 40’s build quality.
Spring rate: 67 psi – 70 psi
Volume Spacers: 4
Low Sped Compression: 13 Clicks Out
High Speed Compression: 15 Clicks Out
Rebound: 11 Clicks Out
As a 170lb CAT 1, I settled on 67psi for traction on race weekends, and bumped up to 70psi when riding bike parks for a bit more pop on jumps. My spring rate and HSC settings were right in line with FOX’s suggested baseline settings. An extra two clicks of LSC from baseline kept the fork stable under braking. I found that running the rebound a few clicks faster than suggested kept the fork riding higher in its travel without sacrificing grip or control.
As compared to the current Boxxer, the 40 is noticeably stiffer. Whether railing ruts at full speed or pinballing through rock gardens with abandon, the fork stays pointed precisely where you direct it. While the newest Boxxer isn’t flexy by any means, the difference is noticeable. Whether that matters is largely up to personal preference, but for those who appreciate maximum steering precision, the 40 provides it.
The damping consistency is remarkable, even on runs that push past the 10-minute mark, which is the primary benefit of the sealed FIT damper. Despite the massive stanchions, the 40 cycles with smoothness that matches the best available forks — a factor that can be attributed to the refined air spring, the stiff chassis, and carefully sized bushings. The travel is supple up top, with sufficient progression deep in the stroke to avoid bottoming on most hits—although in the future I’d prefer to run more volume spacers in order to increase the end-stroke ramp-up. As with the rest of FOX’s air-suspended forks, the 40 does tend to ride deeper in the stroke than a comparable Rockshox offering, which seems to make the fork rely more heavily on the damper for support. As a result, it doesn’t feel quite as pillowy as a Charger damper-equipped Boxxer, but the feedback from the damper never translated into arm pump, and personally, I found that the additional feedback lent a more precise feel for the front tire, which was an asset in situations where traction is hard to find.
The author getting his lean on at Canyons Bike Park, Park City, Utah
With most of its features taken directly from FOX’s Racing Applications Development program, there’s a strong case to be made that FLOAT 40 is as close as you’ll get to works suspension in an off-the-shelf package. It’s supple, stiff, and provides ample fine-tuning options. In spite of my best efforts, I was never able to push the fork past the point of composure. Although I’ve been impressed with the air-sprung Boxxer World Cup, I prefer the FLOAT 40, hands down. Considering my history with the Boxxer, it seems disingenuous not to mention that, for the price-conscious, the coil-sprung Boxxer Team is highly capable and considerably more affordable. However, for those seeking a no-holds-barred competitive advantage, you will not do better than the 2016 FLOAT 40.
The author about to use full travel at Canyons Bike Park, Park City, Utah. #hucktoflat