Fox Float Air Volume Spacer Kit: Installed and Reviewed
There’s a difference between visiting a bicycle at a shop, playing with it in the parking lot, and living with it. Once a frame finds it way into your garage and your heart and you’ve had time to develop a relationship with it, you begin to learn it’s little eccentricities. My best friend, a Transition Double, is a great bike. From the onset I knew that it wasn’t going to be the best climber but its playful nature suits my riding style perfectly.
What I gradually came to understand as our relationship unfolded, is that we didn’t always see eye to eye on rear suspension performance. The single pivot rear end just felt too linear. When the rear shock was set up for my smooth bermy local trails, the jump oriented bike felt great, but over sharp stutter bumps or on big hits – the shock would bottom out harshly.
So how did my bicycle and I resolve our issues?
How to Install the Spacer Kit
Step One: This the most important step for safety reasons! Release all the air from the canister by depressing the Schrader valve. Then gently cycle the shock and mount the bicycle securely to the stand. Position the shock so that it is horizontal(ish) to the ground.
Step Two: Unscrew the air can by firmly turning the canister clockwise and slide it midway down the shock body. You don’t need to push it very far down to insert the spacer.
Step Three: Look under the head of the shock for a steel washer and O-ring. On some bikes there may already be an air-volume spacer in place. Slide the washer down the shaft as pictured. Remove the stock plastic white spacer if necessary.
Step Four: Slip the spacer over the washer with the carved side facing down until it snaps into place.
Step Five: Push the spacer, washer, and o-ring up into the shock head.
Step Six: Supporting the weight of the rear suspension, gently ease the can up to the shock head, and turn it clockwise to tighten. Firmly hold the can while tightening until it is snug before releasing. Otherwise, the negative pressure could be enough to slam the can into the shock head, tear out the threads, and damage your shock.
Step Seven: Inflate your shock and test ride!
Wow. The Float Air Volume Spacer Kit retails for only $25 USD, but it is one of the single biggest improvements to a bicycle I’ve ever made. The spacer reduces the volume of the air canister, which causes the shock to ramp up faster, and feel significantly more progressive.
By changing the air spring compression ratio, you can reduce the amount of air pressure required in the shock, which finally allowed me to set the proper suspension sag. In order to prevent harsh bottom outs in the past, the shock required 15-20 PSI more air than it does with the spacer, which compromised the small bump compliance. A switch from no spacer to the .4″ spacer increased the compression ratio of my shock from 3.0 to 4.0.
This simple modification can easily be performed by a competent tinkerer and offers a pretty big improvement at a very marginal cost. Fox does note that same compression ratios are too high to safely use and “the resulting compression ratio…. combinations is beyond the bounds of product user safety. With a spike of excessive air pressure, the air sleeve can suddenly fail and cause a crash, property damage, SERIOUS INJURY, OR DEATH.” The full list can be found here.