Changing air volume spacers 

In this article we’ll be explaining how to change your air volume spacers in your Rock Shox or Fox Suspension forks. We’ll start by explaining what a volume spacer does, next, we’ll identify why you might want to add or remove a volume spacer or two. Finally we’ll take you through the mechanical process of adding or removing a volume spacer.

What do volume spacers do?

Reducing the amount of space in the air chamber of your fork will affect how your fork moves through its travel.  Examples are key to explaining this so we’ve created two very basic examples.

In this first example you have 100psi over 6 inches of perfectly spherical sealed suspension fork chamber. Compressing your fork by 3 inches will mean that this 100psi becomes 200psi. You have halved the available space by compressing the fork changing and this has changed the air pressure in the chamber.

In a second example after altering your set-up you now have exact same 100psi over 6 inches of fork chamber, just like example a. However in this example you’ve added two volume spacers that have reduced the volume of the fork to only 4 inches. Compressing your fork by 3 inches will mean that this 100psi now becomes 400psi. You have quartered the available space by compressing the same fork by the same amount. This makes the second set-up much more difficult to compress in the later stages of its total travel.

Although this is an extreme example of using volume spacers to alter the pressure in your fork chamber it demonstrates how reducing the volume in your fork chamber might better help you use your suspension travel.

Why would you add or remove a volume spacer?

How do you decide if you should remove a current volume spacer or add a new one? The next time you’re out on the trail pay close attention to your suspension Do you bottom out your suspension lots but like the small bump sensitivity too much to increase your air pressure? Or do you struggle to use the full range of travel and feel that your suspension could do a better job of sucking up those big impacts?

The basic principle of reducing air volume in a suspension fork would increase the amount of pressure needed to compress the fork in the latter part of its travel. On the other hand, increasing the volume inside your fork would decrease the pressure needed to compress the fork in the latter part of its travel.

How to change your volume spacing

Changing your volume spacers is a relatively simple job and shouldn’t take much more than 10 minutes with the right tools in the right environment.

You will need

You could use

Start by taking note of the pressure currently in your forks. You’ll need to remove this air from the system to add or remove a volume spacer so knowing what to pump your forks back up to is a must. Write this down on a notepad or in your smartphone and put to one side

Secondly remove all the air from your forks. You can use a small alan key to push the valve down and release the air.

Now use the applicable sized socket and ratchet to remove the protruding surrounding the air valve. This is directly threaded into the fork crown.

Once this has been unscrewed, remove the valve unit completely from the fork; most volume reducers are placed underneath the air valve unit. This is the only component that needs to be removed.

Depending on the model and manufacturer of your fork you will need to screw on, clip on or slide volume spacers on or off of a rod. This process depends entirely on your specific fork;

Rockshox call their volume spacers ‘tokens’ and the color of the token dictates the fork models it is compatible with. These volume spacers screw together to add or remove volume.

Fox Forks work in two different ways; clip and slide on. Your fork Stanchion you dictate which style of volume spacer is used These volume spacers clip or slide together to add or remove volume to the internals of the fork.

36mm Stanchions differ from the other Stanchions sizes on Fox Suspension forks. The volume spacer will be either blue or orange with a cylindrical appearance and a slot opening down one side.

To install these 36mm volume spacers simply remove the black rubber o’ring from the rod attached to the air valve. Use the opening to slide a spacer over the lower and thinner part of the fork slide the spacer upwards and rotate to lock in place and re-install the rubber o’ring.

Once you’ve added your volume spacers give the entire unit a quick wipe with your clean paper towel to remove any dust.

Carefully re-install the air valve assembly into the fork leg and tighten using the socket and ratchet to manufacturer torque specifications.  Finally use your shock pump to add air back into your system and you’re done.