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For the 2017 model year, many FOX forks will feature a new damper tune designed to provide a smoother, more supple feel while maintaining a similar level of support deeper in the stroke. The change will impact the 32, 34, and 36 FIT4 series. We had the opportunity to learn a little about the update and take it for a test ride to see if the claims hold true on the trail.


FIT4 Damper Explained

FOX's fourth generation FIT4 (FOX Isolated Technology) closed cartridge system has Open, Medium, and Firm compression damping settings, with an additional 22 clicks of low-speed compression adjustment in the Open setting. This video from FOX does a good job of showing how the oil flows inside the damper in each setting. Pay special attention to the Open position.


​What Changes Were Made To The Damper?

Ariel Lindsley, a FOX Engineering Technician, filled us in on the techy details:

"The 'E16 tune' [which will be included in 2017 forks] uses thinner shims overall, but they are arranged in a way so that the larger shims that seal off the compression ports on the piston flex/open a little easier than the 2016 stock tune. The shim stack that controls the higher shaft speed movements is arranged to offer similar support to the stock 2016 tune. This makes the fork feel a little more supple at the beginning of the travel while still offering support when the going gets rough or steep.

If you look at these changes on the dyno, what you see is a decrease in damping in the 0 to 10-inches per second range while maintaining similar damping to the 2016 tune in the 10 to 40-inches per second range.

We are moving the direction of this tune because we feel it gives the rider more comfort and grip, and filters out more of the small trail chop while still having enough support to offer control in the rough and steep sections of trail."

Moar shimz! FOX FIT4 forks will feature an updated damping configuration in 2017.

On The Trail

FOX set up a back-to-back test using a 160mm travel 2016 36 Float FIT4 fork as our tester. Our first two runs were conducted on the stock 2016 fork. Following a quick parking lot swap of the damper cartridge, an additional two runs were performed on the same fork with the new tune. The bike, air spring pressure, number of volume spacers, clicks of rebound damping, compression mode (Open), and clicks of compression damping were kept the same between all four runs.

FIT4 is a closed cartridge system that is relatively easy to swap, which can be pretty convenient at a race or in your garage.

We performed the test on Hummingbird Trail in Simi Valley, California. It's a very fast, rough trail with lots of continuous chatter, some good turns, and a wide variety of drops, bumps, and g-outs.

As claimed, we experienced better small bump sensitivity. This improved traction in many scenarios, especially while braking. The trail has some awkward corners that require you to slow down quite a bit, however you can carry a lot of speed through the sections leading into the turns. That slow down part is key to riding the trail well, and the loose-over-hard dirt type doesn't lend itself to having a lot of traction to begin with (Aaron Gwin calls it "SoCal mud" for a reason). With the new tune installed we found it was easier to get the bike back under total control after holding it wide open on rough straightaways, allowing us to stick tricky lines into turns with more confidence and accuracy. The fork also seemed to dive less under hard braking in rough conditions.


Another instance we noted an improvement was while cruising on smooth portions of trail and hitting a single rock. The new tune allowed the wheel to get up and out of the way easier without jarring our hands, spitting us offline, or making the bike hop unexpectedly. Despite the smoother feel, the fork used similar amounts of travel on big hits, and tended to use slightly less on medium hits.

We also noted that the fork stayed a bit higher in its travel, which lead to some slight pushing in a few turns we previously didn't have issues with. This might be a matter of dropping a few PSI or removing a click or two of compression damping to allow the fork to settle a little further into the travel.

At the end of the session we concluded that the changes were minor, but nonetheless an improvement to the overall ride.

The FOX 36 Float FIT4 fork in all its glory, complete with the new lightweight 15mm Kabolt thru-axle upgrade.

What's The Bottom Line?

Since its introduction, the FOX FIT4 line of forks has provided incredibly quiet, smooth, supple performance with enough support to keep things in check when the going gets rowdy. Moving into 2017 things get even better with an updated FIT4 damper tune. Based on our ride experience, the new tune is a marginal improvement for all riders thanks to improved comfort at the recreational level and superior traction and control for hard chargers. Finding a middle of the road damping configuration that works for a wide range of riders is no doubt a difficult task, and we feel this new tune better addresses the needs of both ends of the spectrum.

Visit for more details, and know that many older models can be updated to the latest tune by contacting FOX directly.

Feature and photos by Brandon Turman

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