For two years, if you wanted Specialized’s GENIE dual-air-spring tech under you, you bought Fox. That’s over. The RockShox Super Deluxe now builds GENIE into its own shock body, and it’s shipping stock on three current Specialized platforms: the Turbo Levo 4, the Turbo Levo R, and the Stumpjumper 15 EVO. Same patented dual-chamber spring Specialized locked up with Fox when the Stumpjumper 15 launched in 2024. Different shock company building it, for the first time.

We already have trail time with the Fox side of this story. Our Stumpjumper 15 EVO review called the FOX FLOAT X GENIE the single biggest upgrade on that bike — the part that kept the rear end composed on a 2,400-foot Galbraith descent that used to cook a standard Float X by the bottom. Now there’s a second version of that same spring wearing a RockShox badge, spec’d on some of the same bikes we’ve already ridden the Fox version of. That’s a real head-to-head, not a spec-sheet hypothetical.

Quick Take

What changed	RockShox Super Deluxe Ultimate now offers Specialized’s GENIE dual-air-spring tech, ending roughly two years of Fox exclusivity
Previously	GENIE was Fox Float X-only, since the Stumpjumper 15’s 2024 debut
Ships on	Specialized Levo 4, Levo R, Stumpjumper 15 EVO
Levo 4 spec	210x55mm, C34 compression tune
Levo R spec	190x55mm, C34 compression tune
Stumpjumper 15 EVO spec	210x55mm, lighter C30 compression tune
How it works	Dual air chambers act as one spring for the first ~70% of travel (supple, grip-focused), then close off for a more progressive, bottomless-resistant last 30%
Frame changes required	None — kinematics stay the same, only the shock changes
OEM only	Yes — this GENIE tune isn’t sold aftermarket, built specifically for these Specialized frames
Best for	Riders cross-shopping Fox- and RockShox-equipped Specialized builds who want to know if the shock choice actually matters
Skip if	You’re buying used or aftermarket — this shock isn’t available outside these OEM spec builds

Why Fox Had This Alone for Two Years

Specialized owns the GENIE patent, not Fox. That detail got lost a little in 2024, when the Stumpjumper 15 launched with the FOX FLOAT X GENIE as its headline suspension upgrade and most of the coverage treated it as a Fox invention. It wasn’t. Specialized designed the dual-air-spring concept and its Ride Dynamics team contracted Fox to build the first production version, exclusively, for the initial run of bikes. Bikerumor’s reporting on the RockShox announcement confirms that arrangement and its expiration: Specialized has now opened a parallel partnership with RockShox to build a matching GENIE-equipped shock for the same bikes.

Two years is a normal runway for this kind of exclusivity deal in the suspension world — long enough for the launch partner to own the story, short enough that the patent holder can widen the supply chain once the tech’s proven out. Specialized did the same kind of staged rollout with the Levo 4’s motor ecosystem before opening more build options. GENIE getting a second shock vendor isn’t a surprise so much as a formality that finally landed.

How Does the RockShox Super Deluxe GENIE Shock Work?

GENIE is Specialized’s patented rear shock design: two connected air chambers function as one large spring through the first 70% of travel, giving a flatter, more coil-like spring curve for grip and chatter absorption. Through the final 30%, the outer chamber closes off, ramping progression so the shock resists blowing through its travel on square-edged hits — without any change to the frame’s kinematics.

That’s the same mechanism whether the shock body says Fox or RockShox on the side. Mountain Bike Action’s writeup and Bikerumor’s both describe the same 70/30 split in the RockShox version, and per Bikerumor, RockShox built genuinely bespoke hardware for it rather than adapting an existing shock: a unique eyelet, sealhead, air can, damper shaft, and air can token, all specific to this application. This isn’t a standard Super Deluxe Ultimate with a GENIE sticker slapped on. It’s a shock built from the shaft out to run Specialized’s spring architecture.

The Spec Breakdown: Three Bikes, Two Tunes

Here’s where the head-to-head gets specific. RockShox isn’t running one GENIE spec across the lineup — it’s tuning the shock differently depending on which bike it’s bolted to:

Bike	Shock size	Compression tune
Specialized Levo 4	210x55mm	C34
Specialized Levo R	190x55mm	C34
Specialized Stumpjumper 15 EVO	210x55mm	C30 (lighter)

The Levo 4 and Levo R share the same C34 tune despite running different shock lengths, which tracks with both bikes carrying the same 3.1 motor and 840Wh battery weight even though the Levo R is the lighter-travel, e-downcountry-leaning platform. The Stumpjumper 15 EVO gets the lighter C30 tune, which makes sense for an analog trail bike that isn’t hauling motor and battery mass and doesn’t need the same compression support to manage it.

That’s a genuinely useful data point if you’re cross-shopping builds. The shock isn’t identical across the range just because it says GENIE on the can — RockShox tuned it per platform, the same way Fox’s FLOAT X GENIE spec varies by frame.

Fox GENIE vs. RockShox GENIE: Is It Actually the Same Ride?

Flow Mountain Bike’s first ride is the most useful account so far, since it’s the only outlet that’s actually ridden the new shock rather than just reported the spec sheet. Their take: the spring curve is functionally identical to the Fox version, and the RockShox shock rallies through rocks and roots at speeds that feel like more rear travel than the bike’s numbers suggest — the same illusion-of-travel effect we noted on the Fox GENIE in our own Stumpjumper 15 EVO testing.

Where the two diverge is the damper, not the spring. The Super Deluxe Ultimate runs RockShox’s RC2T damper with independent high-speed and low-speed compression adjustment — no cross-talk between the two circuits, according to RockShox. Fox’s FLOAT X GENIE uses Fox’s own compression circuit and adjustment layout. Same spring philosophy, different damping character and different tuning knobs underneath it. If you’re the kind of rider who actually turns those dials rather than leaving them at the factory baseline, that’s the part of this story that matters more than which badge is on the shock body.

We haven’t put miles on the RockShox version ourselves yet — this is sourced reporting on a shock that’s days old in the market, not a trail test. We’ll update this post once we’ve ridden one back-to-back with the Fox GENIE bike we already know.

Who’s Actually Getting This Shock

This isn’t a running change across every build in the Specialized lineup. Per Gravity Coalition’s coverage, the RockShox GENIE spec is landing on specific Stumpjumper 15 EVO build tiers, paired with RockShox Lyrik forks rather than Fox 36s on those bikes. It’s a parallel build option sitting alongside the existing Fox-equipped versions of the Stumpjumper 15 EVO, Levo 4, and Levo R — not a replacement for them.

That matters for anyone currently shopping these bikes. You’re not choosing between an old shock and a new one. You’re choosing between two current, factory-backed versions of the same suspension concept, built by two different companies that don’t usually cooperate on proprietary tech.

Why This Is Bigger Than One Shock Spec

Component exclusivity deals are common in the bike industry — brands lock in a launch partner, generate headlines, then widen supply once the platform is established. What’s less common is a second major suspension brand building genuinely bespoke internals (not a badge-swap) to match a rival’s patented spring design mid-product-cycle. Our rear shock buyer’s guide already lists the standard RockShox Super Deluxe Ultimate as one of the better air options on the market at large; this GENIE variant is a different, OEM-only animal built specifically around Specialized’s kinematics, and it won’t show up as an aftermarket upgrade for your own frame.

It’s also a signal about how much leverage GENIE has picked up since 2024. Shock companies don’t build platform-specific hardware for someone else’s patent unless the OEM relationship is worth the engineering cost. Specialized clearly thinks GENIE is worth having on both suspension brands’ order sheets, and RockShox clearly thought it was worth the investment to not lose that OEM spec entirely to Fox.

Who Should Care About This

Anyone deciding between Fox- and RockShox-equipped builds of the Levo 4, Levo R, or Stumpjumper 15 EVO. This is the actual buying decision GENIE’s expansion creates. If your shop has both options in stock, the shock choice now comes down to damper preference and brand ecosystem, not which one gets the “good” spring — both do.

RockShox loyalists who skipped these bikes over the Fox spec. If proprietary Fox internals were the thing keeping you on the sidelines, that’s no longer the whole story. You can now get the same dual-air-spring behavior with RockShox’s damper and tuning language.

Riders who already own the Fox-equipped version. Nothing changes for you. Your GENIE shock isn’t obsolete, and this isn’t a running update you need to chase.

Who Should Skip This

Anyone hoping to retrofit GENIE onto a different frame. Per Bikerumor’s reporting, the RockShox version uses hardware built specifically for these Specialized platforms. It’s not a standalone aftermarket shock you can bolt to another bike’s kinematics.

Buyers who already have a strong Fox-vs-RockShox preference for other reasons. Damper feel, service network, tuning app ecosystem — those differences are all still real and still the bigger factor in most people’s decision. GENIE parity narrows the spring-curve gap; it doesn’t erase everything else that separates the two brands.

The Bottom Line

Fox’s exclusive window on Specialized’s GENIE tech is over, and RockShox didn’t just license a compatible shock — it built platform-specific hardware to run the same patented dual-air-spring concept inside its own Super Deluxe Ultimate, tuned differently for the Levo 4, Levo R, and Stumpjumper 15 EVO. Early trail reports say the spring curve rides the same as the Fox version we’ve already tested; the damper and tuning character are where the real choice lives now. For a shopper cross-referencing builds, that’s good news either way — the spring that made GENIE worth talking about in 2024 is no longer locked to one suspension brand.

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Reporting sourced from Bikerumor, Mountain Bike Action, Flow Mountain Bike’s first ride, and Gravity Coalition. No RockShox Super Deluxe GENIE test unit has been ridden by our team at time of publication.