New Fox 40 Float RC2 fork brings air springs to DH racing

By Eric McKeegan. Photos by Thomas Dietze and Matt DeLorme.

Fox recently released news of redesigned forks and rear shocks, upping the ante in the gravity arms race. While Dirt Rag couldn’t snag an invite to Spain for the official unveiling, we got the low-down on the new suspension bits, and we’ve got a request in for review samples.

Let’s breakdown the new stuff:

2014 40 Float RC2

 

The Fox 40 has been around for almost a decade, seemingly chugging along with little fanfare while scoring piles of pro level downhill wins. In 2010 Fox began experimenting with an inverted design, and while pro riders like Aaron Gwin and Gee Atherton found it had sufficient fore/aft stiffness, it wasn’t stiff enough laterally. Eventually the project was abandoned.

In the last few years the forks may have seemed the same, but inside the forks of most of the top-level pros Fox was experimenting with an air spring system. As opposed to the inverted design, this prototype dominated the 2011 and 2012 World Cup seasons, culminating in the 2012 World Championship under Greg Minnaar.

While working on the 2013 Float air springs for the single crown fork line, Fox developed one for the 40. Besides loosing the weight of a coiled spring, the spring rate is adjusted via shock pump, not spring swaps, from 45 to 80 psi. The Air spring is designed to be linear in the initial part of the travel, becoming more progressive in the second half of the travel. The compression ratio is internally adjustable with a new nine-position compression piston, as seen in the upper right of the photo above. The orange negative spring is titanium. The RC2 damper is new as well, with a Kashima coated shaft and no hydraulic bottom out—the air spring negates the need for one. Travel remains at 203mm.

The lower casting is completely new as well, with a new axle pinch bolt system, a new arch design, DH post mounts for the brakes, and an air bleed system to reduce internal pressures due to elevation changes. The 150g saved here is equal to the weight lost by tossing the coil spring. Smaller changes to the stanchion tubes and crowns save additional weight. Even the steering stop bumpers when on a diet to save 4 grams! Also worth noting is there will be a 650b-compatible lower.

 

Now ready for the masses, the 40 Float RC2 drops more than a pound off the previous version (claimed weight is 5.98lbs.) while claiming to retain its renowned stiffness and improving suspension performance.

DHX RC4

Dropping weight from the DHX wasn’t one of the design goals for 2014, but what was on the list? To design and tune front and rear suspension as a system, improve damping control, increase responsiveness and sensitivity, and win races.

Unlike the fork, which is a simple 1 to 1 ratio of shock stroke to wheel travel, the shock needs to be handle a variety of leverage ratios. Most downhill bikes have been trending towards building progressiveness in to the suspension design, making it less important for the damping system to provide progression. The new DHX is more linear, but still retains the air assist and air volume adjusters to tune progression.

The big change, and a surprise in an industry that seems hellbent on making everything “oversize”, the shock shaft is reduced from five eights of an inch to half of an inch. This might not seem like a huge change, but the test riders (the guys you see on the podiums all the time) noticed increased traction due to decreased friction. The smaller shaft also means more room for oil, a good thing for keeping internal temperatures down and extending oil change intervals.

There really isn’t any question about if this stuff works, it’s already scored multiple World Cup wins. The cool thing is the average mortal gets to ride the same stuff; we just have to pay for it. In fact the price is only thing that didn’t improve. The 40 will set you back about $1,700, DHX is looking like $600.