Custom tune, damping upgrades or expensive coil conversions. The market for fork tuning is large and tricky to navigate. One of the cheapest and most effective upgrades for an older SoloAir RockShox fork is the DebonAir spring. We’ll guide you through the upgrade step by step to help you bring a noticeable improvement to the performance of your fork.
Larger negative air chambers are all the rage, whether as an aftermarket upgrade or as a feature in the latest forks. The larger chamber is supposed to improve the responsiveness of the fork and also keep it higher in its travel. That means significantly more grip and less arm pump on the trail. Last year, RockShox unveiled the new DebonAir spring in their high-end PIKE, Lyrik and Boxxer models. After many hours on bikes with the new and the old air springs, we can say: The DebonAir spring actually delivers a significant performance boost compared to the SoloAir. The best part: you can upgrade your SoloAir forks (all 35 mm single crown forks from RockShox) to the DebonAir system at home for as little as € 47. If you want to, you can also use the opportunity to change the travel on your fork or go ahead and give it a small service while you’re at it. Our step-by-step guide will show you how to go about it and what to look out for.
Before we get into the depths of your fork, there are three things that you need to keep in mind for your own safety:
- The geometry of your bike is designed around a specific axle to crown fork length. If you change the travel with the new air spring, you will also change the length of the fork. By doing so, you can experiment with the geometry of your bike. A longer fork will bring up the front end and slacken the head angle. But beware: your frame is only certified up to a certain amount of travel. Check the basic specs of your frame beforehand.
- Cool, so I can now I can run my PIKE with 180 mm travel! No, you can’t. Depending on the year and exact model there are limitations here. You should run a maximum of 160 mm travel on the PIKE and Revelation forks. Lyriks and Yaris (after 2016) will go up to 180 mm without problems. Of course, you can also reduce the travel. But let’s face it, who wants less travel?
- Watch out for the spacers. And by that we don’t mean the spacers under your stem that go rolling around the workshop as you take out the fork. We’re talking about the volume spacers in the air chamber. Changing the travel also changes the maximum number of spacers that fit into the air chamber. You can find a table listing the details on sram.com. With a larger negative air chamber, you can usually reduce the number of volume spacers needed in your fork.
Unfortunately, we don’t quite live up to our function as role models here. Rather play it safe and use gloves and goggles, especially when opening up a fork for the first time.
Surely you need special tools? Unfortunately yes, no matter if you’re working on your fork or shock. Sure, you could find most of the tools to do the basic work on your suspension in Grandpa’s old toolbox in the attic, but you’ll need a few special tools when replacing the air spring. If you plan on doing more in-depth work on your suspension at home, you will definitely need the right tools for the job.
If you’re just going to replace the air spring this once, please don’t go out and buy a special tool kit. You can get a syringe at the pharmacy, and instead of the pick, you can use a very small Allen key or a toothpick. And if you don’t have a rubber mallet, you can use a piece of soft wood to place between the object you’re hammering and the hammer. There’s no getting around the internal retaining ring pliers though. Without them, you won’t be able to remove the air spring and exchanged it.
Replacing the air spring step-by-step
1. Removing the fork
If you want to do it the quick and dirty way, you can turn your bike upside down and change the air spring with the fork still on the bike. Brakes don’t get along with fork oil though. We would definitely advise inexperienced mechanics to remove the fork and clamp the steerer tube in a work stand.
2. Let out the air
The next step is critical for your safety! If you don’t know your air pressure, simply attach the shock pump and note the indicated pressure. Then let out all of the air, and we mean all of it! If you know your air pressure, want to change the travel of your fork or want to try a new set-up anyway, you can also vent the air with an Allen key. To be absolutely sure, remove the valve core.
Tip: once you’ve let out the air, cycle the fork through its travel to release the air from the negative air chamber as well.
Tip: for the quickest way to get back to your original setup, make a note of the number of rebound and compression clicks.
3. Removing the lower fork legs
You will find two bolts on the bottom of the fork that hold the fork together. The red rebound adjuster knob covers the bolt on the damping side of the fork. This might look different, depending on the model of your fork. If the adjuster knob is attached with a grub screw, loosen it with the 2.5 mm Allen key a few turns and pull the knob off with your hand. If your adjuster has no screw, it is clamped on and you can pry it off carefully with a flat-head screwdriver.
Loosen the two bolts on the bottom of the fork with the 5mm Allen key about half way (four to five turns), so they stand off from the lower fork legs but are still well within the thread.
Now grab your rubber mallet and hit the bolt heads until they come up against the casting. This should have dislodged the air and damper shafts from the legs. Now you can remove the bolts. To avoid the oil from spilling out, tilt the bottom of the fork upwards.
Tip: if your hammer is too big and you can’t hit the bolts, use the 5mm Allen key as an “extension”.
Close both holes with a bit of tape. This makes it easier for you to drain the old oil without spilling it all over your workshop floor.
Tilt the fork back down and pull off the lower legs. There will be a little oil inside the legs. Empty it into a bucket and dispose of it properly at a later stage (the kitchen sink is not the right place to get rid of old oil!). Wipe away any remaining oil with a clean rag.
4. Removing the old air spring
If you’ve made it this far – well done! Things get a bit trickier when removing the old air spring. It is important that you do not damage the air spring and damping shafts. These are the two silver rods protruding from the stanchions.
This is where it gets tricky. Hopefully, you did a better job of removing the air than we did. Which is why we needed a hammer. Of course, this isn’t the proper way of doing it and we wouldn’t recommend doing the same at home. The correct way: using a flat-head screwdriver or your Allen key, push the SoloAir seal head tab (the black disc) into the stanchions and rotate the little “nose” so it sits under the retaining ring.
With the tips of the retaining ring pliers in the eyelets of the retaining ring, you can easily compress the ring and pull it out. Be careful not to scratch the air shaft! The retaining ring is extremely stiff. You will have to use retaining ring pliers. Believe us, we’ve tried removing it with a flat-head screwdriver and failed miserably.
Your old air spring should now be loose in the stanchion. Firmly grip the shaft with both hands, push it into the stanchions slightly and then give it a firm tug to pull it out.
Tip: if you simply can’t hold on to the shaft, screw the 5 mm Allen bolt back into the shaft and wrap a cloth around the shaft and bolt. That will give you a better grip.
Now you’ve got to clean everything: using isopropyl alcohol, a clean cloth and a long dowel, wipe down the inside of the stanchion. Once you’ve cleaned everything you can re-grease it with fresh fork grease.
5. Installing the DebonAir spring
There’s more to the new DebonAir spring than the red colour. The seals have been improved and, above all, it has a significantly larger negative chamber for a noticeable boost in performance.
With clean fingers (and gloves), apply a liberal amount of RockShox seal grease on the seals, o-rings, and the air shaft
Insert the new air piston into the stanchion until the red seal head is firmly in place and you can’t push it in any further
Pay attention not to scratch the air shaft when reinserting the retaining ring. Compress the retaining ring with the retaining ring pliers and slot it into the designated groove.
Tip: the retaining is properly seated in the groove when you can easily turn it with a screwdriver.
6. Now give your fork a little love
Seeing as you’ve already dismantled your fork, you might as well give it a “small” service.
Using the pick or toothpick, remove the foam rings below the dust wiper seals
As you can clearly see, the foam rings, usually off-white, have collected a lot of dirt. Spray them with isopropyl alcohol and carefully dab them with a cloth. Next, clean the inside of the lower legs.
Soak the clean rings in a bit of fresh fork oil.
Tip: we always use the bottle cap from our cleaning spray.
Once the rings are soaked through, you can insert them back into the legs. Important: the rings can twist very easily when you insert them. Make sure the rings fit snugly in their slot without being creased or twisted.
Check the dust seals. Inspect them for damage. If they are brittle and cracked, they need replacing. If – as in our case – the seals are still ok, coat them liberally with fork grease. On the inside, of course, but be careful not to get any grease on the foam rings!
7. Fitting the lower legs
Those rings were not in my upgrade kit?! These are the metal rings of the dust wiper seals. We find it’s easier to push the legs onto the stanchions without them on the seals, which is the next step.
Make sure the legs are the right way around and that the dust wiper seals don’t fold over as you push on the legs. Push the legs onto the stanchions so that they’re firmly in place but not yet touching the spring and damper shafts.
Tip: apply a little oil to the end of the stanchions with your fingers to allow the legs to slide on more easily.
Now you can play doctor. Fill the syringe with 10 ml fork oil and inject the oil into the air spring side through the hole in the bottom of the leg. Note: some forks only need 5 ml of oil on the damping side, others 10 ml. Fortunately, the exact amount is printed on the 5 mm damping side bolt. If not, the same applies here as on the spring side. If in doubt, check the correct amount of oil in the RockShox service manual.
Grab the matching bolts (the one with the hole on the damping side!) And your 5mm Allen key or your torque wrench and tighten both bolts. Remember: don’t over-tighten. If you have a torque wrench, set it to 7 Nm. (In case of doubt: always check the service manual!)
Now attach the rebound adjuster and …
… slide the metal rings of the dust wiper seals into place
Attach the shock pump, adjust the air pressure, put the fork back onto the bike, and done!
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Words: Felix Stix Photos: Christoph Bayer