EXT Aria
MSRP: €1,060 / $1,150 USD
Adjustments: Main and secondary air pressure; rebound; low- and high-speed compression; hydraulic bottom out
- 210 x 50 mm
- 210 x 52.5 mm
- 210 x 55 mm
- 230 x 57.5 mm
- 230 x 60 mm
- 230 x 62.5 mm
- 230 x 65 mm
- 250 x 67.5 mm
- 250 x 70 mm
- 250 x 72.5 mm
- 250 x 75 mm
- 185 x 50 mm
- 185 x 52.5 mm
- 185 x 55 mm
- 205 x 57.5 mm
- 205 x 60 mm
- 205 x 62.5 mm
- 205 x 65 mm
- 225 x 67.5 mm
- 225 x 70 mm
- 225 x 72.5 mm
- 225 x 75 mm
Intro
EXT’s coil shocks have been deservedly-popular high-end options for some time now; we’ve been impressed with a number of iterations of the Storia, as well as the Arma MX that we tested on the Canfield Jedi last year. Today they’re launching their first air-sprung mountain bike rear shock, the Aria — or simply “Air” in Italian.
While the Aria is EXT’s first air-sprung mountain bike shock, it’s not like they don’t have experience working with air springs, dating back to some work with the Williams F1 team quite some time ago, and more recently, the Era MTB fork. If you want to hear a whole lot more about the history of EXT and their philosophy on suspension design, check out Episodes 110, 140, and 146 of Bikes & Big Ideas with their founder, Franco Fratton.
We first saw prototypes of the Aria in person at Sea Otter 2022 and with the 2023 iteration of the show just around the corner, the Aria is now available to the public (and we’ve got one on the way for review). But what’s going on with the design of the Aria, and what sets it apart from the many other options for a high-end air-sprung shock? Let’s have a look.
Design
The Aria is a high-volume air shock meant for Trail through DH bikes (and is offered in a range of metric sizes in both standard and trunnion mounts to suit, as listed above). Perhaps the most interesting bit about the Aria’s design is the air spring itself. Like most modern air shocks, the Aria has an adjustable positive air spring with a self-equalizing negative chamber. But unlike just about every other rear shock I’m aware of (the Chickadeehill LFB6, which I’ve never so much as seen in person, being the lone exception), the Aria adds a second independently-adjustable positive chamber to the mix.
[If a refresher on what we’re talking about with positive and negative springs would help right now, our Vorsprung Secus review has a detailed rundown.]
The secondary positive chamber in the Storia takes the place of the volume spacers that most air shocks use to tune the amount of progression in the spring, and in doing so produces somewhat different results. In short, the secondary ramp-up chamber is separated from the main positive air chamber by a floating piston and is set to a much higher pressure. When the shock starts to compress, the main positive chamber compresses until its pressure reaches that of the ramp-up chamber, at which point the piston separating the two starts to move and both compress in unison. In effect, this turns the two into a single higher-volume chamber that ramps up more slowly from that inflection point onward.
The idea is that this arrangement (EXT calls it “HS3”) makes for a more linear, coil-like spring curve with more midstroke support than a conventional air spring design, while still having the adjustability and ability to tune the overall amount of progression that you get from an air shock. The greater the difference in pressure between the main positive chamber (labeled “+” on the Aria) and the ramp-up one (“++”), the deeper in the stroke the two start to move in unison, and therefore the more the spring ramps up through the midstroke. That’s somewhat in contrast to the more typical volume spacer arrangement in most air shocks, which have more of an effect late in the stroke. EXT has some nice graphs that illustrate the differences in spring curves, both between altering volume spacers in shocks that use those, and in separately changing the + and ++ pressures in the Aria. EXT says that riders can more precisely target the behavior they want in a specific part of the stroke with greater ability to fine-tune performance and with fewer effects on other parts of the stroke than is possible with a more conventional volume spacer arrangement.
I’ve been a big fan of this style of dual-positive air springs in a variety of forks over the years, including EXT’s own Era, and a few other forks from Manitou and Ohlins, so I’m quite curious to see how it pans out in a rear shock. EXT also says that they’ve managed to package all of that with just two dynamic seals separating the three separate air chambers in an effort to reduce friction, and have paired that with a proprietary surface coating on the sliding parts for especially smooth operation. The Aria also uses EXT’s newly-formulated EV2S damper fluid, which they say has especially consistent performance across a wide temperature range to reduce damper fade.
The Aria’s damper is based on the design of the e-Storia but reconfigured for use in an air shock. It’s a monotube design with adjustable rebound, low- and high-speed compression, and an externally adjustable hydraulic bottom-out circuit that increases compression damping in the final 15% of the stroke. The idea here is to provide speed-sensitive bottom-out resistance that increases damping when the shock is near bottom-out and still compressing quickly; this arrangement also has the benefit of not returning the energy that it absorbs to the rider on rebound in the way that a spring (or bottom-out bumper) would.
The Aria also features EXT’s Lok 2.0 climb switch, which, when activated, directs oil flow through a secondary compression circuit with a preloaded valve for additional low-speed compression damping to improve pedaling efficiency. The Lok switch’s damping isn’t externally adjustable but can be re-valved as part of a regular service if desired.
Some Questions / Things We’re Curious About
(1) How is the dual-positive chamber HS3 air spring going to work in a rear shock? We’ve been consistently impressed with similar designs in forks, but will it translate to a very different package?
(2) And how is the Aria going to stack up against its excellent coil-sprung counterpart, the Storia, and which one will work best for what sorts of riders? In theory, the Aria sounds something like a lighter, more tunable version of the Storia but is that borne out? (The Storia is also exceptionally light for a coil-sprung shock, so we’re curious to see how the Aria compares weight-wise. EXT hasn’t yet published a stated weight for the Aria but we’ll report back once we have one in hand.)
Bottom Line (For Now)
We’ve been very impressed with a number of iterations of EXT’s coil shocks over the years, so we are quite excited to see how the Aria stacks up. We’ve got one on the way for review, so stay tuned for much more on the Aria — including comparisons to the Storia — coming soon.
The usual excellent and detailed review. Assuming the ride review is positive, I’d be likely to buy this just for the ability to tune without replacing VRs.
Sounds sweet. Looking forward to the full review.