Arrival of the new DebonAir spring warrants a closer look, not least because it’s backwards compatible with existing RockShox 35mm forks.

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New RockShox DebonAir spring need to know

• New DebonAir spring comes stock on 2021 Pike, Lyrik, Revelation and Yari and is designed to give a taller ride height.
• By moving the air assembly up inside the fork, the positive and negative springs balance at top-out, eliminating the downward spike in positive pressure inherent to the current design
• A taller seal head moves the air piston head up by 10mm so it now sits directly in the transfer port (dimple)
• Because the air-piston moves relative to the dimple, the upgrade is backwards compatible with existing Pike, Lyrik, Yari and Revelation forks, you just need the new seal head and foot nut, with will be available as spare parts.

There’s a war raging. Or to be more precise, an arms race; a show of suspension might if you like. Earlier this week Fox dropped a WMD in the form of the new Fox Float 38. Now RockShox retaliates with an updated DebonAir spring that will feature on all new Pike, Lyrik, Revelation and Yari forks. We suspect this is just a flare to check the lay of the land before RockShox deploys some heavy artillery of its own

So what’s changed?

On the face of it just a couple of small parts. Dig a little deeper however and it’s obvious that subtle changes to the relative position of the bypass port that balances positive and negative spring pressures should bring noticeable changes to the ride quality of the fork. The main one being an elevated ride height, where the influence of the negative air spring is less apparent, especially where it pulls the fork into the sag position and reduces the total amount of available travel.

What’s really neat about the way RockShox has achieved this transformation, is that it hasn’t actually moved the position of the dimple in the upper tube. Instead, it raised the height of the air spring assembly inside the upper tube so the piston head (black) now sits in the dimple (bypass port) when the fork is topped out.

RockShox used a two-pronged approach to achieve its goal. First up, it added a 10mm taller seal head (red) to position the piston head right in line with the dimple. Then it was just a case of adding a longer foot nut (also red) to the bottom of the air shaft to make up for the short fall in its overall length. And the best part is, if you have a current fork, you only need the new foot nut and seal head, not the complete DebonAir spring assembly, to bring your fork bang up to date. And to make it even easier, RockShox will make both available as a spare parts kit.

And while the internal changes aren’t easy to visualise, the key takeaway here is that the head of the air-piston now sits directly at the bypass port when the fork is fully extended. As such, the negative spring gets charged at the same time as the positive so it will make set up easier. It also means the negative spring pressure will be lower, which is key to achieving the increased ride height of the fork. An additional benefit of the new design is that because there’s now no positive pressure increase before the air-springs equalise, RockShox has also eliminated the momentary drop in positive air pressure that used to happen as the piston head passed the dimple.

Now, if you’ve been following along, you’ll have realised that the upwards shift in the new DebonAir spring assembly means that the positive air-spring volume is now smaller, so the fork should ramp up more, right? Not so fast. Using tech first introduced on the Boxxer, the new seal head that sits at the bottom of the upper tube is now hollowed out on the backside. So, just like the air channels on the new Fox 38 fork, the hollow seal head increases the ambient air-volume in the lower legs so it contributes less spring force at bottom out. In a nutshell, this makes it easier to get full travel. And according to RockShox, even with the associated reduction in positive spring volume, the net result is no increase in spring force at bottom out. Also, because the fork now rides higher in the travel, the positive spring volume will actually increase a little dynamically.

As such, the recommended air-pressures remain unchanged for Lyrik and Yari, but RockShox is recommending a 5psi pressure drop for Pike and Revelation, and that’s largely due to the increased support that’s built in to the Charger dampers of the short-travel forks.

So the new DebonAir spring increases the ride height of the fork, makes it easier to set up and eliminates the downward spike in positive spring pressure associated with the older design. All positive changes them, and because it’s an easy, affordable retrofit, it could also be a good tuning option for anyone looking for a higher front end.