Changing the volume reducers in your fork or shock is an internal adjustment that allows you to change the amount of mid stroke support and bottom out resistance on your suspension. Because all bikes are different, because everyone has their own suspension setup preferences, and because we are all riding different trails, there isn't one suspension setup that works for everyone out there. What we are all after is finding the sweet spot where the suspension is balanced from front to rear. The only way to find that sweet spot is to go out and ride. The best place to start is right in the middle. Depending on the model and amount of travel, Fox ships out their forks with a range of different volume reducers installed, all aimed to be neutral on the scale of linear to progressive. Adding more volume reducers gives you more mid stroke support and bottom out resistance, making the spring curve more progressive. Removing volume reducers does the opposite, making the spring curve more linear. Get out on the trail and see what works best for you and your bike. Follow along this How To so that you have the know how for changing volume reducers on your 2020 Fox suspension fork.
The tools for this job are simple. First off, and most importantly, you will need a top cap 6-point socket for your specific Fox fork. Today we a working on a Fox 49, which uses a 32mm top cap socket. We will be using the branded Fox top cap socket, and there are a few reasons why this is no ordinary socket. One, the Fox top cap sockets are made from 7000 series aluminum, allowing you to remove and install the top cap without gouging the top cap itself. Two, because the top cap on the fork is very shallow, the Fox socket does not use a chamfer. On most ordinary sockets there is a chamfer/relief on the bottom side of the socket to help you get the socket on to the fastener a little bit easier. If you were to use a traditional socket on your Fox top cap, you run a high risk of that socket slipping off and scarring the top cap. In the photos below, you can see the flat bottom of the Fox socket.
The Fox 40, 49, and 36 forks use a 32mm socket for the air spring top cap, and the Fox 34 and 32 forks use a 26mm socket for the air spring top cap. All Fox top cap sockets use a 3/8" drive. If you don't have the appropriate chamfer-less socket, you can also use a set of Knipex pliers. These Knipex pliers are great because the jaws always close parallel to each other and allow you to get a strong grip on many types of fasteners. You still need to be very careful when removing and installing your Fox top cap with a pair pliers like these. We do not recommend using any other types of pliers, impact sockets, or a Crescant wrench on your Fox top cap.
You will also need a shock pump to add air back in to your fork once everything is back together. We will be using a Fox Digital Shock Pump to get exact pressure settings. Of course you will need your Fox fork volume reducer kit. Each Fox fork uses different size volume reducers. The different volume spacers are differentiated by color and also say which model fork they are to be used for on the bottom. Lastly, if you are installing volume reducers on a Fox 40 or 49 dual crown fork, you will also need a 5mm hex key to loosen the top crown pinch bolt on the air spring side of the fork. Let's get to it.
The Fox top cap sockets do not use a chamfer on the bottom of the socket to help keep them from slipping off of the top cap
The parallel jaws on these Knipex pliers are great, and these can be used as a backup to not having the right socket. These are not your ordinary set of pliers
To start things off, we want to release all of the air inside the air spring of the fork. It's always a good habit to release the air when doing any kind of service to your suspension fork. Remove the air cap and use the topside of the cap to depress the air valve.
When it's time to remove the top cap on your Fox 40 or 49 dual crown fork, it's important to first loosen the top crown pinch bolt on the air spring side of the fork. When this pinch bolt is torqued down, it can prevent the top cap from unthreading. Use a 5mm hex key to loosen the pinch bolt. If you are working with any single crown Fox fork, you can skip right over this step.
Using a chamfer-less 6 point socket and 3/8" drive socket wrench, remove the air spring top cap. The top caps on all Fox forks use a traditional thread and so lefty loosey, righty tighty. Because we are working on a Fox 49 here, we will be using a 32mm chamfer-less Fox top cap socket. Remember that the Fox 40, 49, and 36 forks use a 32mm socket for the air spring top cap. The Fox 34 and Fox 32 forks use a 26mm socket.
Because the "nut" on the air spring top cap is very shallow, be sure to press down firmly on the socket so that it doesn't slip off and scar the top cap. Loosen the top cap and unthread it all the way until it can removed.
Changing the volume reducers inside both your Fox fork and rear shock is an internal adjustment that allows you to change the amount of mid stroke support and bottom out resistance. Adding more volume reducers/spacers increases the force required to compress the fork or shock through the middle and bottom of the stroke. This makes the spring curve more progressive and will keep the fork or shock higher up in its travel. Removing volume reducers decreases the force required to compress the shock or fork through the middle and bottom of the stroke. This will make the spring curve more linear. Finding the sweet spot between air pressure and volume reducers is key. Adding more volume reducers isn't always the right answer. If you are struggling to use full travel, it might be beneficial to remove a volume reducer and continue using the same pressure.
Here we are working on a Fox 49 that uses 203mm of travel. We are going to be adding 1 volume reducer, going from 5 to a total of 6 tokens. Each of the volume spacers clip and unclip in to each other. Just snap another one on and you're good to go. This should give the bike more mid stroke support, helping the fork stay higher up in its travel. Finding a setup that is balanced from front to back is what keeps the bike stable when the trail gets rough.
40 and 49 forks use red volume reducers, 36 forks use orange, 34 forks use green, and 32 series forks use blue
Installing the top cap is pretty straight forward. Once you have the number of volume reducers installed that you want, slide the top cap back in to the fork and starting threading it in by hand. Turn the top cap by hand as much as possible, and then tighten it down using the same socket from before. You will feel when the top cap is bottomed out and snug. Don't try to over tighten it. Once it's tight, it's tight.
Working our way backwards now, if you are working on a dual crown fork, be sure to tighten down the top crown pinch bolt and torque it to roughly 8 N*m.
Thread the shock pump on to the air valve and start pumping up the air spring. Because the Fox Float NA2 air spring uses a positive and negative spring air chamber, be sure to equalize the air in both chambers by cycling the fork as you pump it up. You can do this in 20-30 psi increments to make things easy. If you listen closely, you can hear the air escape from the positive air spring in to the negative air spring. Cycling the air into the negative air spring will give you an accurate reading of the positive spring pressure on the shock pump. Throw the air cap on when you are done and you will be ready to go!