EXT Vaia Fork
Travel Options: 170, 180, 190, and 200 mm
Wheel Size Options: 29’’
Available Offset: 44 / 48 mm (adjustable)
Stanchion Diameter: 38.5 mm
Axle Options: 20 x 110 mm Boost or 15 x 100 mm Boost (convertible)
Blister’s Measured Weight: (200 mm travel, 20mm axle, uncut steerer tube): 3,300 g
MSRP: €2,150
Intro
EXT has been making rear shocks for DH bikes for quite some time — in fact, that’s where they got their start in the bike world — but they haven’t had a fork to go with them, until now.
[Check out Ep.110 of Bikes & Big Ideas with EXT founder, Franco Fratton, for more on the company’s history, and how they moved into the mountain bike industry after starting in motorsports.]
But back to the new Vaia fork: it’s an inverted dual-crown with some design elements that will be familiar to folks who have gotten to know EXT’s first mountain bike fork, the Era — plus a bunch of very intriguing new features and details, too. While the Vaia is intended to be a true DH fork, EXT has also given it some interesting features to better support use on burlier Enduro bikes. Let’s see what they’ve come up with.
Design & Features
By far the most visually obvious thing that sets the Vaia apart is its inverted layout. That’s not a new concept, of course — the Manitou Dorado, Push Nine One, and Intend BC’s various offerings are all current examples of the stanchions-on-the-bottom layout. There have been several others over the years, to say nothing of the myriad inverted motorcycle forks out there.
Still, inverted mountain bike forks are the exception rather than the rule, so it’s noteworthy that EXT has gone that route with the Vaia. A lack of torsional stiffness has been a common complaint with many inverted mountain bike forks over the years, but EXT has some tricks up their sleeve to address those concerns.
The Vaia’s axle — the only thing tying the lower legs together, given the inverted layout — is especially beefy. It’s made from titanium rather than the more conventional aluminum, and it features hexagonal interfaces at the dropouts to help lock the legs together and prevent twisting. It’s a floating design to accommodate slight variations in hub width without binding the legs and uses two pinch bolts (also made from titanium) per dropout to clamp everything together.
Interestingly, while the Vaia is built to use a 20 mm axle, EXT also offers a 15 mm one with an adapter for the non-drive-side dropout to step down to the smaller version. EXT recommends sticking with the 20 mm version for 190 and 200 mm travel setups but says the 15 mm one is viable if you want to run the Vaia at 170 or 180 mm travel. Speaking of the dropouts, the Vaia comes with a 200 mm rotor mount, which EXT says you can bump up to 220 mm maximum with an adapter.
The Vaia also features pressure relief buttons to vent out any excess air that accumulates in the upper tubes, and stanchion guards that are compatible with a bolt-on fender (sold separately).
Spring Design
Back to the spring design and travel options: the Vaia can be configured with 170 to 200 mm travel via internal spacers (in 10 mm increments). Most modern air-sprung forks equalize pressure between the positive and negative chambers via a dimple machined into the inside of the stanchion that bypasses the air piston near the topout position, and thereby requires that the piston land at a specific spot in the stanchion for the system to work. That, in turn, requires changing the length of the air shaft in order to change travel. The Vaia is a mostly air-sprung fork (more on that in a moment), but EXT instead uses a spring-loaded valve that the air piston opens as it approaches the topout position, so they’re able to use travel-reducing spacers instead.
Like EXT’s single-crown Trail / Enduro fork, the Era, the Vaia uses a version of their “HS3” spring. In short, it’s an air-sprung design with a second, independently adjustable second positive chamber to adjust how the fork ramps up deeper in the stroke.
The main positive air chamber (“+”, in EXT’s parlance) is the only positive chamber in play in the early part of the stroke. The secondary “++” chamber uses a higher pressure than the + one, and the ++ chamber only starts to play a role once the fork has compressed enough to increase pressure in the + chamber to the point that the piston separating the two has equal force acting on both sides. That arrangement means that the spring curve ramps up more quickly earlier in the stroke for better midstroke support than you’d get with a more conventional spring layout. Once the ++ chamber comes into play, the + and ++ ones effectively act as a single larger-volume chamber and the rate of progression falls off so that the spring rate doesn’t continue to increase as dramatically.
Finally, EXT also includes a small, third positive coil spring with a very limited stroke that only acts in the very first part of the travel. The idea is to let the coil spring compress right off the top to reduce the breakaway friction associated with air spring seals.
That’s all conceptually the same as the Era’s spring, albeit with some packaging tweaks to accommodate the different chassis. However, the Vaia also offers volume spacers that can be used to reduce the volume of the ++ and/or negative chambers to further tune the spring behavior. Adding spacers to the ++ chamber increases the amount of ramp-up deep in the stroke (just like volume spacers in a more conventional fork with a single-positive air chamber). Reducing the volume of the negative chamber doesn’t change the shape of the spring curve much, but it makes for more support through most of the travel range without introducing a more aggressive ramp-up deep in the travel.
Damper
As with the air spring, the Vaia’s damper design is similar to that of the Era single-crown fork. It’s a sealed cartridge with a spring-backed IFP, offering adjustable rebound plus high- and low-speed compression. The main piston is designed to induce turbulent flow, and thereby minimize the effects of oil viscosity variations due to changing temperature on the damping characteristics.
Some Questions / Things We’re Curious About
(1) I’ve been a big fan of EXT’s first mountain bike fork, the Era (especially the updated V2.1 iteration). Given their spring and damper similarities — but wildly different chassis layouts — how similar (or not) do the two feel?
(2) What about that inverted chassis in general? The last inverted fork I’ve spent a lot of time on is the current Manitou Dorado, and while its not-super-torsionally-stiff chassis has some real upsides in certain areas, I have at times wished it was a bit more precise in how it responds to steering input. Does the Vaia feel similar on that front, or is it appreciably stiffer?
(3) How does the Vaia compare to the broader class of dual-crown DH forks in general?
Bottom Line (For Now)
Inverted mountain bike forks still aren’t terribly common, but we’ve seen a few new ones pop up in recent years, and the EXT Vaia is the latest addition to that club. I’m awfully curious to see how it performs, and how it stacks up to the whole crop of modern dual-crown DH forks. We’ve got a Vaia in for review and I’ve spent a bit of time on it already, so check out our Flash Review at the link below, and stay tuned for a Full Review to come.
Flash Review: Our Initial On-Trail Impressions
BLISTER+ members and those who purchase our Digital Access Pass can check out the Flash Review below to read our initial on-trail impressions. Get our Digital Access Pass to view all our Flash Reviews and Deep Dives, or become a BLISTER+ member today to get access to that and a LOT more, including the best worldwide Outdoor Injury Insurance, exclusive deals and discounts on skis, personalized gear recommendations from us, and much more.
Flash Review — EXT Vaia
EXT’s new Vaia is an inverted dual-crown fork with additional features and design details that set it apart from most of the DH fork market — at least on paper. But how does it stack up on the trail? Check out our early thoughts.
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