Specialized Stumpjumper 15 Review | A hugely adjustable new trail bike with a clever custom shock


The not-so-minor details

Product

Specialized Stumpjumper 15

Contact

Specialized

https://www.specialized.com/

Price

From $8,900 AUD ($14,500 AUD as tested)

Weight

14kg

Positives

- Supremely supple suspension
- Massive bottom-out composure
- Efficient & neutral pedalling performance
- Dialled geometry for all-round handling
- Broad range of tuning & setup options
- Practical frame design with SWAT storage
- Mixed wheel compatible

Negatives

- High entry price
- No alloy models (yet)
- Proprietary shock will scare off some
- i9 hub end caps fall out way too easily

Wil reviews the 2025 Specialized Stumpjumper

The most recent version of the Specialized Stumpjumper launched in 2020 alongside the Stumpjumper EVO. Having earned plenty of media praise from around the globe, it didn’t take long for them to be established as two of the most popular trail bikes on the market.

As well received as they’ve been over the past four years, Specialized was eager to simplify its mountain bike lineup and reduce the amount of overlap between models. With the arrival of the longer travel Epic 8 and Epic EVO, a reshuffle further up the order was on the cards.

For 2025 Specialized has amalgamated the previous Stumpjumper and Stumpjumper EVO into a new bike called the Stumpjumper 15. The number refers to it being the 15th generation of the platform, which first arrived all the way back in 1981. There are very few bikes on the market that can claim that kind of lineage, making it a newsworthy event whenever a new version rolls around.

So how big of a deal is the new Specialized Stumpjumper 15, and just how different is it to its highly commended predecessors? I’ve been riding one over the past few weeks to find out!


Watch our video review of the 2025 Specialized Stumpjumper 15:


While I don’t doubt the testing that Specialized has invested into the new bike and shock, the proof is always going to be in the pudding. Thankfully in this case, the pudding is absolutely delicious.

2025 specialized stumpjumper 15 pro
Wil’s been putting the new Specialized Stumpjumper to the test over the past few weeks.

An overview of the Specialized Stumpjumper 15

Following three years of development, the Specialized Stumpjumper 15 arrives as an all-new, long-travel trail bike.

Splitting the difference between the old Stumpjumper and Stumpjumper EVO, the new version features a 150mm travel fork and 145mm of rear travel. Most models roll on dual 29in wheels, though each frame is capable of fitting a 27.5in rear wheel by way of an aftermarket mullet link. It’s also compatible with 160mm travel forks and coil shocks, making for quite a versatile package that will go head-to-head with the latest Trek Fuel EX, Canyon Spectral, Merida One-Forty and Giant Trance X.

The Stumpjumper 15 is built around a brand new FACT 11m carbon fibre frame that incorporates the updated SWAT 4.0 downtube storage. As with the latest Levo SL, the distinctive sidearm is no more. Instead, Specialized has put more material into the main linkage to minimise wiggle between the key pivot points. The new frame is claimed to be slightly stiffer than the old Stumpjumper EVO, despite the overall weight remaining much the same.

2025 specialized stumpjumper 15 pro
The Specialized Stumpjumper 15 will replace the old Stumpjumper and Stumpjumper EVO.

The Fox GENIE shock

At the heart of the Stumpjumper 15 is a proprietary shock that has been developed by Specialized’s in-house Ride Dynamics team and manufactured in partnership with Fox Racing Shox.

Called the GENIE, it’s essentially a Fox Float with a secondary air sleeve around the main shock body. This additional chamber creates a huge volume of air for the first 70% of the travel, providing a much flatter spring curve that aims to deliver a super plush, coil-like feel.

2025 specialized stumpjumper 15 pro
The Fox Float GENIE shock features a unique air spring that was developed in-house at Specialized.

At the 70% mark the outer sleeve is automatically cut off, drastically shrinking the available air volume. It does this using the GENIE band, which is a large slide bushing made by Trelleborg. As the shock is compressed, the GENIE band is pushed up and over the transfer ports between the primary air chamber and the outer sleeve. With the transfer ports closed off the air volume becomes much smaller, creating a significantly more progressive spring rate for the final 30% of the stroke.

In effect, it’s a bit like putting a huge volume spacer inside your shock to help it ramp up and resist bottom-outs. However, the key difference with a conventional air shock filled with volume spacers is that you don’t lose the plushness and sensitivity that makes up the majority of the travel. Clever eh?

A Specialized PSA

Specialized calls its patented air spring design Pneumatic Spring Assist, or PSA for short. It’s a relatively simple but innovative solution that aims to address the compromise of balancing sensitivity and support within a typical air shock.

2025 specialized stumpjumper 15 pro
The outer air chamber creates a huge volume of air for the first 70% of the travel.
2025 specialized stumpjumper 15 pro
At the 70% mark the GENIE band pushes past and closes off those little transfer ports, dramatically shrinking the available air volume for the final 30% of the travel.

It’s worth noting that the PSA system differs to shocks that utilise a hydraulic bottom out function, which is usually designed to pad out the final 10-20% of the stroke. Specialized states that because those hydraulic systems are speed sensitive, they can create a pronounced wall of damping on harder hits. In comparison, PSA kicks in at the 70% mark and is designed to be less of a bump-stop due to the way it ramps up support progressively. It’s also scaled by how much air pressure you have in the shock, so the spring rate is specific to the weight of the rider.

While the PSA design is nifty, we should point out that modifying a shock’s air volume isn’t a new concept. It is basically the opposite of the Fox DRCV design used on old Trek and Gary Fisher bikes, and Scott utilises a similar volume-boosting outer sleeve on its Nude shocks, albeit with a different purpose. There are plenty of other examples on the market including the EXT Aria shock, Öhlins air-sprung forks with their three-chamber air spring, and the SD Components DVC.

The execution varies quite a bit between them all, and so too does the adjustability. In the case of the GENIE shock, Specialized wanted to make things as simple as possible. There’s just a single air valve, and the way the shock ramps up through its stroke is fully automated. Really all you need to do is set sag and dial in the rebound damping, and away you go.

2025 specialized stumpjumper 15 pro
Red clip-on spacers are used to adjust the volume in the outer chamber, which affects the feel of the first 70% of the stroke.

Volume spacer tuning

For those who want to dive deeper however, it is possible to tune the volume of both air chambers on the new Fox GENIE shock.

The outer sleeve utilises red, two-piece plastic volume bands that clip together around the main body of the shock. One comes fitted from the factory, and you can fit up to four if you’re after a poppier and firmer feel to the first 70% of the travel. Or you can remove all of the volume bands for maximum plushness and grip. This range of adjustment has a profound impact on the ride quality, which I’ll touch on in more detail shortly.

You can also adjust the the main air chamber in the eyelet using conventional-looking Fox volume spacers. This allows you to increase or decrease the amount of ramp-up in the final 30% of the stroke depending on how much bottom-out resistance you’re after. A 0.2³ volume spacer comes as standard, which can be removed to reduce progression. Alternatively, you can fit a bigger 0.4³ volume spacer to increase progression.

2025 specialized stumpjumper 15 pro
You can also adjust the end-stroke progression using volume spacers in the eyelet like a conventional Fox Float shock.

Otherwise the GENIE features all the standard adjustments you’ll find in a conventional Fox Float shock. There’s a single rebound dial, a two-position lever for engaging the Firm mode, and a three-position adjuster for fine-tuning the compression damping in the Open mode. The overall construction and damper architecture are much the same, though of course the compression and rebound circuits have been tuned for the Stumpjumper’s kinematics.

If you’re turned off by the proprietary shock, you’ll be happy to know that pretty much any air or coil shock will fit the Stumpjumper frame. In fact, there’s a specific model that comes fitted with a coil shock as standard.

Conversely, the GENIE shock could be used on other bikes and the team at Specialized indicated it works really well on the current Levo SL. That leads us to believe we’ll be seeing this design fitted to more mountain bikes in the future. And given the PSA patent also covers use inside a fork, perhaps Specialized will be cooking up something for the front of the bike too.

2025 specialized stumpjumper 15 pro
Otherwise the GENIE shock is very similar to a regular Fox Float.

Specialized Stumpjumper geometry & size chart

Geometry on the new Specialized Stumpjumper 15 is nearly identical to the old Stumpjumper EVO, which is a very good thing.

Covering a broad range of rider heights, there are a whopping six frame sizes to choose from. The smallest S1 and S2 come standard as a mullet, while the S3-S6 sizes are equipped with dual 29in wheels from the factory. As mentioned before, each frame is compatible with either wheelsize at the rear by swapping the linkage. Aftermarket links will be available for $100 AUD for the alloy version and $300 AUD for carbon.

One notable difference with the new Stumpjumper 15 frame is its improved seatpost insertion. This means longer travel droppers come as standard, with our S3 size featuring a 185mm BikeYoke Revive.

2025 specialized stumpjumper 15 pro
The Specialized Stumpjumper retains its angle-adjusting headset.

Otherwise the 450mm reach and 64.5° head angle carry over from the Stumpjumper EVO. So too do the modular headset cups, which allow you to adjust the head angle between 63-65.5°.

There’s also a two-position flip chip in the chainstay pivot. This comes set up in High from the factory, and flipping that into Low will drop the BB by 7mm and slacken the angles by half a degree. Along with the wheelsize flexibility and the option to fit a 160mm travel fork, there’s quite the breadth of options for setting up the Stumpjumper to your preference.

2025 specialized stumpjumper 15 geometry size chart
Specialized Stumpjumper 15 Geometry & Size Chart
2025 specialized stumpjumper 15 pro
Most models come with a 150mm travel fork, though the frame will accept up to 160mm.

2025 Specialized Stumpjumper price & specs

At the time of launch there will be five models in the Specialized Stumpjumper 15 lineup with prices kicking off at a not-insignificant $8,900 AUD for the Comp.

Unfortunately there’s no sign of a cheaper alloy frame at the time of writing, though we suspect that’ll be coming at a later date.

Regardless of price all Stumpjumper 15 models are built around exactly the same FACT 11m carbon frame. The only variation is the S-Works model, which substitutes the alloy shock extender for a slightly lighter carbon version. The S-Works frameset will also be available on its own should for those who’d prefer to build up their own custom bike.

One thing to note is that the carbon Stumpjumper frame doesn’t allow for mechanical shifting, which means it is only compatible with wireless drivetrains. It’s a big move by Specialized that will see all models coming with an electronic SRAM groupset, including the Comp that debuts the new S-1000 Eagle AXS Transmission.

Most bikes are equipped with a 150mm travel Fox 36 and the Float GENIE shock. The exception is the Öhlins model, which features a bigger 160mm travel fork, a coil shock and a mullet setup with a heavier duty rear tyre.

Read on for all the specs and prices below, followed by our review of the Specialized Stumpjumper 15 Pro.

2025 specialized s-works stumpjumper 15
The S-Works Stumpjumper sits at the top of the tree with its SRAM XX Transmission, Reverb AXS dropper and Maven Ultimate brakes.

2025 Specialized S-Works Stumpjumper 15

2025 specialized stumpjumper 15 pro
Equipped with the same Factory Series suspension as the S-Works model, the Pro actually comes with a longer stroke dropper courtesy of BikeYoke.

2025 Specialized Stumpjumper 15 Pro

2025 specialized stumpjumper ohlins coil 15
Prefer mullets and coil suspension? The Specialized Stumpjumper Öhlins gets a bigger 160mm travel fork, a coil shock, a mixed wheel setup and a burlier rear tyre. Looks shreddy!

2025 Specialized Stumpjumper 15 Öhlins Coil

2025 specialized stumpjumper expert 15
The Specialized Stumpjumper Expert gets the same top-end suspension internals as the S-Works model, albeit at a much lower price.

2025 Specialized Stumpjumper 15 Expert

2025 specialized stumpjumper comp 15
Currently the cheapest option in the lineup, the Specialized Stumpjumper Comp is one of the first bikes to come with the new SRAM S-1000 Transmission.

2025 Specialized Stumpjumper 15 Comp

2025 specialized s-works stumpjumper frameset 15
For those who want something a little different, there’ll be a standalone frameset too.

2025 Specialized S-Works Stumpjumper 15 Frameset

Plonk the Stumpjumper into a nasty rock garden and its supple suspension sees it float through with a remarkable level of isolation between your feet and the ground.

2025 specialized stumpjumper 15 pro
Geometry and sizing on the new Specialized Stumpjumper 15 is very close to the old Stumpjumper EVO.

Sizing & fit

At 174cm tall I’ve been riding the S3 size Specialized Stumpjumper 15, which is effectively a Medium. It’s a great-fitting bike, with the 450mm reach and 627mm stack being pretty much identical to the previous Stumpjumper EVO.

You’re positioned quite centrally within cockpit, with the 77° seat angle and short 165mm crank arms contributing to a fairly tall saddle height. As such, you’ll benefit from running the bars on the higher side for seated comfort. Thankfully the fork’s steerer tube isn’t chopped super short, and there are plenty of headset spacers for dialling in the stem height.

2025 specialized stumpjumper 15 pro
As always, Specialized puts a lot of effort into getting the ergonomics right.

The 800mm bars were too wide for my tastes, so I cut those down to 760mm. This improved the fit, but it does reduce the available flex making the 35mm diameter carbon bars feel particularly stiff.

Otherwise I’ve gotten along swimmingly with the excellent Deity grips and the ludicrously comfortable Specialized Bridge saddle with its soft Mimic padding. Along with the 185mm travel BikeYoke dropper post and its adjustable Triggy remote, the ergonomics on this bike are likely to please a lot of riders.

2025 specialized stumpjumper 15 pro
Longer droppers come as standard thanks to the improved seatpost insertion.

Suspension setup

Despite the proprietary GENIE shock, setting up the suspension on the Specialized Stumpjumper is simple.

30% sag is recommended, which equated to 155psi to support my 68kg riding weight. I then set rebound damping a little faster than halfway (8/14 clicks).

As for the black low-speed compression dial, I found the suspension was a touch too soft in position one. Adjusting that to position two helped to calm it down nicely. You can also flip the blue lever into the Firm mode, which isn’t quite a full lockout but still provides a usefully strong platform for commuting on the road and heading up smoother climbs.

Up front is the latest Fox 36 with the new GRIP X2 damper. I started out with the recommended settings and two volume spacers, but in search of a plusher feel to match the insanely smooth rear end I ended up dropped the pressure from 74psi to 68psi. If I need more support for flowier and jumpier trails, I’ll add an extra couple of clicks of high-speed compression damping.

2025 specialized stumpjumper 15 pro
Set your air pressure for 30% sag, dial in the rebound damping and away you go.

Specialized Stumpjumper weight

Confirmed weight for our Specialized Stumpjumper 15 test bike is 14kg without pedals and with the tyres set up tubeless. That’s on the money for an aggressive long-travel trail bike these days, especially considering the big dropper post, SRAM Maven brakes and 200mm HS2 rotors.

According to Specialized, the new Stumpjumper 15 frame weighs 3.07kg including the shock. The S-Works model is claimed to knock off 120g with its carbon link, dropping the weight just below the 3kg barrier. For those wondering, the Float GENIE shock weighs 458g, which is within 20g of a Float X piggyback shock.

I also had the chance to weigh the new Roval Traverse SL 11 carbon wheelset, which came in at an impressive 1,795g. Compared to previous models, the redesigned carbon rims utilise a much shallower depth for compliance and 5mm thick beads for greater impact strength. They offer quite a tight fit with the stock tyres, and combined with the deep central channel you need a fair amount of pressure to get the beads to seat properly. They also feature thread-in tubeless valves, which are a nice touch.

Wrapping the wheels is a Specialized Butcher (1,045g) and Eliminator (998g) tyre combo, both with the reinforced GRID Trail casing. I fitted a CushCore Pro insert in the rear wheel as usual and set pressures at 19-22psi up front and 21-23psi out back depending on the conditions.

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The floaty suspension performance is the first thing you’ll notice aboard the Specialized Stumpjumper 15.

What do we dig about the Specialized Stumpjumper 15?

Climbing aboard the Specialized Stumpjumper for the first time, the way the rear suspension sinks into its travel immediately reminded me of the Enduro. It is seriously plush back there, giving you the impression that you’re sitting on a much longer travel bike.

Inspired by the latest Levo SL, the leverage rate is slightly lower and it’s a little less progressive than the old Stumpjumper EVO. Combined with high volume shock and bearing-driven extension link, the suspension eases through its travel like a hot knife glides through butter. The result is an insanely supple rear end that offers coil-like reactivity through that first 70% of the travel.

Of course there are some big marketing claims from Specialized behind its fancy new shock, and there’s even a full-blown white paper that delves into how it was tested and benchmarked against the previous Stumpjumper EVO and Enduro. Using data acquisition to measure the difference in speed between the front and rear wheels, Specialized claims the GENIE offers a “57% reduction in traction loss time” compared to a standard air shock. It also states that while the new Stumpjumper has 25mm less travel than the Enduro, it “equals the amount and quality of travel used for the magnitude of impacts in the ‘Bump Zone’“. Put simply, the GENIE shock is claimed to improve traction and provide more effective bump absorption across the majority of impacts experienced during a typical trail ride.

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The mid-stroke reactivity allows the rear wheel to get out of the way quickly, maintaining grip and composure through chunky rock gardens.

While I don’t doubt the testing that Specialized has invested into the new bike and shock, the proof is always going to be in the pudding. Thankfully in this case, the pudding is absolutely delicious.

Plonk the Stumpjumper into a nasty rock garden and its supple suspension sees it float through with a remarkable level of isolation between your feet and the ground. The shock’s hyper-sensitivity sees it absorbing trail rubble of all shapes and sizes, keeping the tyres driving into the dirt to maximise grip.

It isn’t just effective on straight-line impacts either. Thanks to notable compliance from the chassis, low-profile rims and supple tyres, off-camber traction is similarly impressive. It tracks smoothly through rough, blown-out corners, helping you to maintain your chosen line with less chance of getting pinged off-course.

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Despite the supple feel, the GENIE shock produces excellent support and pop when boosting jumps.

Bottom-outs begone!

On harder and bigger hits, the Stumpjumper’s newfound bottom-out resistance becomes blindingly obvious. The GENIE shock ramps up significantly in the final 30% of the stroke, adding a tonne of support for absorbing harsh landings.

According to Specialized the PSA design results in 39% fewer severe bottom out events compared to a standard air spring. My experience would concur with this and, try as I might, I was never able to hit full travel despite all of my awful line choices and ugly hucks-to-flat.

After a few rides I ended up removing the 0.2³ volume spacer from the eyelet. This allowed me to access full travel and occasionally push the o-ring off the stanchion on the hardest of impacts, but even then the bottom-out was quiet and controlled thanks to the shock’s progressive air spring and thick MCU bumper.

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Jack trying (and failing) to bottom out the GENIE shock on the Specialized Stumpjumper.

What’s also impressed me about this support is the amount of pop the PSA air spring offers. Far from just muting the end of the travel, the shock retains a liveliness to it with a dynamic platform for your feet to push against. The additional spring force allows the shock to recover faster following a large impact, resulting in less hesitation and hang-up when you hit full travel. Rebound isn’t spiky or uncontrolled though, which I suspect is due to the way the spring rate drops once the shock extends past the 30% mark.

This end-stroke cushioning and stability had a bigger effect on descending proficiency than I expected. Knowing you won’t be met with harsh metal-on-metal contact every time you come walloping back down to earth means there’s less arse-puckering on faster and rowdier descents. Along with the powerful Maven brakes, incredible composure from the fork’s GRIP X2 damper, and the gecko-like traction from the Butcher T9 up front, the Stumpjumper exudes confidence when thumping down highly technical terrain.

Of course the excellent geometry plays a big role in the overall handling package. So too does the sturdy frame, which feels particularly stout through the centre of the bike. It’s quite low-slung even with the chainstay flip chip in the High position, putting your centre of mass close to the ground. Weight distribution is excellent, resulting in fabulous cornering performance and a level of composure that encourages you to push as hard as you dare.

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No surprise that the handling is dialled on the Specialized Stumpjumper.

It loves technical climbing too

Despite the overt plushness and muscly build kit, the new Stumpjumper is actually a great pedalling bike. It is plenty efficient, with a kinematic that sits right in between the old Stumpjumper and Stumpjumper EVO.

Anti-squat hovers around 100% at sag, which provides taut response under pedalling inputs. It manages to do this while still being thoroughly active, delivering a neutral feel when traversing across rocky and rooty surfaces. The floaty suspension helps you to maintain momentum without the rear wheel getting hung up, making for one of the most rewarding and best pedalling bikes I’ve ridden across rough ground.

There’s very little feedback through the pedals, and you’re treated to huge amounts of rear wheel grip. Along with the comfortable riding position and short crank arms, the Stumpjumper relishes in cleaning challenging features on technical climbs.

2025 specialized stumpjumper 15 pro
We were surprised with how efficient and neutral the Specialized Stumpjumper is on rocky and rooty climbs.

On steeper inclines however, I did find the big volume shock to be too squishy under weight shifts. The wallowing sensation was especially noticeable when I was tired and not pedalling smoothly, which resulted in more bobbing. To address this, I decided to open up the GENIE shock and explore its tuning capability.

Tickling the GENIE

As it turns out, changing the number of volume bands in the GENIE’s outer sleeve has quite a dramatic effect on the ride quality. It’s also an easy adjustment to perform. Simply depressurise the shock, remove the retainer ring and pull the air sleeve down to reveal the red volume band within. You can add or subtract volume bands before refitting the air sleeve, all without having to remove the shock from the bike.

2025 specialized stumpjumper 15 pro
The Fox GENIE shock comes with a single red volume band installed in the outer chamber, and there’s room to fit up to four should you wish for more support and feedback.

Given I could do this on the side of the trail, I set out on a short but varied loop to do some back-to-back testing. I benchmarked the first run with the factory setup before packing the outer sleeve with all four volume bands.

Straightaway I noticed a much firmer and more responsive feel to the rear suspension. The squishiness I’d experienced before was gone and the whole bike felt much perkier when heading uphill. The shock sat higher in its travel, resulting in greater pedal clearance and a more direct feel to the steering. Overall it was much closer to the old Stumpjumper, with more pop and support when pushing into jumps and high-speed berms. The downside was a lot more feedback through the pedals on rougher descents. Though still effective at soaking up bigger hits, the rear suspension had lost much of the hyper-sensitivity and dirt-clenching grip that I’d been enjoying before.

2025 specialized stumpjumper 15 pro
With the outer chamber packed with volume spacers, the Specialized Stumpjumper is vastly more responsive through high-speed berms.

Two bikes, one shock

For the following lap I removed all of the volume bands, and holy mackerel, what a difference! It literally felt like I was on a different bike, which was both good and bad.

Up the first climb the Stumpjumper was much soggier. The anti-squat meant it was still responsive when I was pedalling forcefully, but it would sink into its travel the moment my bodyweight would shift rearwards. Consequentially, this took weight off the front wheel and made it more likely to wander around on steep climbs. As a result I needed to make more regular use of the two-position lever to engage the Firm mode.

2025 specialized stumpjumper 15 pro
Climbing performance also improves when running more volume bands inside the outer chamber.

Heading back down the mountain, the rear suspension was oh-so-smooth. At its maximum air volume the GENIE shock is stupendously supple, which sees it pulling off a very good impression of the Enduro. Even on the most chundery of rock gardens it feels like you’re riding on a cloud with almost no feedback through your feet. Traction is glue-like, though since you have the same amount of support from the air spring in the last 30% of the travel, there’s still a surprisingly good amount of pop.

Perhaps the only downside is a slight mismatch with the fork. The Fox 36 GRIP X2 is superb, but I think I’d extend it to 160mm of travel if I was going to run the GENIE in its plushest configuration.

My final test was with two volume bands, which ended up being the Goldilocks setting. The rear end of the Stumpjumper still offers amazing compliance, but it’s more balanced with the fork and it’s noticeably better going up technical climbs. There’s a nice combination of support and grip for all-round trail riding, which keeps the Stumpjumper feeling lively and fun to ride.

2025 specialized stumpjumper 15 pro
What’s impressive about the GENIE shock is just how different it makes the whole bike feel between the two extremes.

While this was my preferred setup, the beauty of the GENIE design is that you can modify air volume easily and quickly to match your preferences and terrain. Riders who like slithering their way down steep, off-piste trails in the woods can remove the volume bands to maximise grip. Alternatively, if you’re going to be boosting air-flow trails like Air Ya Garn in Derby and the Hero trail in Bright, pack it full to increase support.

Any downsides?

In terms of the overall ride quality of the new Specialized Stumpjumper, there have been very few flies in the ointment so far.

Riders who are looking to push their limits on enduro-type terrain may wish for a 160mm travel fork, though thankfully that’s an easy enough upgrade to make by fitting a longer air shaft into the Fox 36. Or just pick the Öhlins model to begin with.

2025 specialized stumpjumper 15 pro
Riders looking to race enduro will want to extend the fork to 160mm.

Conversely, and while the Stumpjumper is a great technical climber, some folks may be put off by the lack of any suspension widgets. The shock’s Firm mode is fine for smoother ascents, but the damping is too heavy for proper singletrack. In comparison, the Scott Genius also utilises a proprietary volume-changing rear shock but it’s remote activated and allows you to select an effective short travel mode for the climbs. Perhaps it’d be cool to have some sort of external adjuster for modifying the GENIE’s volume on-the-fly, but then again the simplicity is a big part of the appeal. That’s even more apparent when comparing the Stumpjumper’s clean cockpit alongside the busy handlebar remote and additional cables on the Genius.

On the topic of climbing, it’s worth noting that while the weight of our test bike is appropriate for aggro trail riding, it is over a kilo heavier than the flex-stay Stumpjumper Pro we tested back in 2020. For riders who own the previous Stumpjumper and appreciate its lower weight, you’ll likely want to look towards the new Epic EVO instead. Thanks to its superb geometry and extra travel, it’s a remarkably capable XC bike that effectively carries on where the old Stumpjumper left off.

2025 specialized stumpjumper 15 pro
The Specialized Stumpjumper 15 is the logical successor to the Stumpjumper EVO. Those who are looking for a lighter and sprightlier package should consider the latest Epic EVO.

Really the new Stumpjumper 15 is the successor to the Stumpjumper EVO. Its frame, suspension and spec package are all designed to excel on more challenging terrain, and as such you can expect to see it being raced by Specialized athletes in the Enduro World Cup.

In my opinion then, the biggest downside is the cost of entry. $9K is a big wad of cash for the Comp model, and it leaves a huge gap that we hope will be filled by cheaper alloy models in the future.

As for our Stumpjumper Pro test bike, the overall value for money is dependent on what you compare it with. It’s expensive alongside the similarly-equipped Giant Trance X Advanced 0 ($10,999 AUD) and the Merida One-Forty 10K ($11,499 AUD), but it’s very much on par with the Santa Cruz Hightower X0 ($13,999 AUD) and the Pivot Switcblade Pro X0 ($14,699 AUD). You could even consider it a relative bargain alongside the astonishingly expensive Trek Fuel EX 9.9 X0 ($15,999 AUD).

2025 specialized stumpjumper 15 pro
The Specialized Stumpjumper Pro isn’t a cheap bike, but its value really depends what you’re comparing it to.

Component highs & lows

Given its lofty price tag, I’m happy to report that the build kit on our Specialized Stumpjumper Pro has been mostly top-notch.

The SRAM X0 Transmission is excellent, and I’ve appreciated the extra clearance of the 165mm crank arms. They do have the effect of making the gearing feel a little taller, so I’d consider fitting a 30T chainring if I were to continue riding this bike as a 29er.

I’d also fit smaller rotors to reduce some weight at the axles, though it’s worth pointing out that the S3-S6 frame sizes require a minimum of 200mm at the rear. And to be honest, I’ve really enjoyed the power and consistency of the SRAM Maven brakes. They offer a similar feel and level of modulation as the Codes, albeit with a serious ramp-up in power when you pull hard on the levers.

The BikeYoke Revive dropper has also been flawless. The action is fast and snappy, and the Triggy remote feels great. I did have some squishiness out of the box, though a few cycles using the Reset function eliminated any play and had the post feeling rock-solid again. Nice.

All the Specialized finishing kit works well, and I’ve been particularly impressed with the Roval Traverse SL 11 rims. They’re light and responsive, but it’s the quiet and nicely damped ride quality that’s stood out the most. They’ve shrugged off some serious arse-clenching rock strikes too. The only annoyance comes from the Industry Nine hubs, which feature flimsy end caps that fall out way too easily every time you remove the wheels from the bike.

2025 specialized stumpjumper 15 pro
The Fox 36 GRIP X2 is an excellent fork with a huge amount of tuning options.

Big props also go towards the Fox 36 GRIP X2 fork. I was kind of expecting this bike to come with the GRIP X damper, which is lighter, simpler and comes with a firm climbing mode to match the shock. Still, the GRIP X2 offers impressively smooth performance in a highly adjustable package that gravity-oriented riders will no doubt be happy with.

What about the custom shock?

Our experience with the Fox Float GENIE shock has been positive so far, though of course it’ll need to be proven in the mass market before long-term durability can be commented on.

That said, it is a pretty simple design that relies on a similar air sleeve construction to the Float X2. It’s also less complicated than Scott’s Nude shock, and those have been in circulation for quite some time.

The main point of difference is the GENIE band, which is basically a big slide bushing. The Ride Dynamics team told us they haven’t worn one out yet, and that it seems to get better over time as it burnishes in. Even still, shock service kits will include a replacement.

2025 specialized stumpjumper 15 pro
The GENIE band (that’s the grey cylindrical piece in the middle of the shock) is a slide bushing made by Trelleborg.

Durability aside, we expect there’ll be riders questioning the use of an inline shock over one with a piggyback. The general theory is that a piggyback shock will offer more consistent damping performance due to its larger oil reservoir that resists heat buildup.

Specialized ended up testing out this theory, measuring the temperature differential experienced between the Float, Float X and Float X2 shocks. The results showed the inline Float shock did get around 10% hotter than the others, though purportedly there was no real-world decline in damping performance. This was a bit of a surprise to the Ride Dynamics team, which credited modern damping oils for their ability to better manage temperature fluctuations.

What was more noticeable was the impact of temperature on the air spring. That’s because when the shock heats up, the internal air pressure increases. However, because the GENIE shock has a much higher air volume to begin with, it was proven to be better at managing temperature and the resulting changes in pressure. In fact, Specialized claims the GENIE’s higher air volume has a more positive impact on suspension consistency compared to simply having a higher volume of oil. So there you go.

2025 specialized stumpjumper 15 pro
The updated SWAT 4.0 storage system is easily the best on the market.

Frame finish

The Stumpjumper’s frame has been similarly low-fuss. It comes with all the features we’ve come to expect from a modern Specialized mountain bike including a threaded BB and generous bolt-on armour for the downtube and chainstay. There’s also a tidy mudflap over the main pivot to prevent debris from getting jammed up in there.

The SWAT 4.0 storage is excellent, with a nice and wide opening that allows you to stuff quite a bit of gear inside. A lower profile hatch offers improved sealing against the elements, with a discreet and ergonomic lever locking it in place.

We’re thrilled to see the cables and brake hose avoiding the headset, and the internal guide tubes will make things a lot easier when it comes time for replacement. The lack of routing for a cable-operated drivetrain will surely disappoint Shimano fans, but perhaps this indicates the Japanese brand will have a wireless groupset coming soon? As cool as that would be, we’ll believe it when we see it.

2025 specialized stumpjumper 15 pro
Is the Specialized Stumpjumper one of the best trail bikes we’ve tested? Without a doubt.

Flow’s Verdict

Given our experience with previous versions, we had lofty expectations coming into this review of the new Specialized Stumpjumper 15.

In many regards it isn’t a dramatic departure from the old Stumpy EVO, and that is indeed a very good thing. We’re glad to see the geometry carried over along with the flip chips and adjustable headset. Combined with the mullet link and coil shock compatibility, there’s a plethora of setup options to suit different riders and trail conditions. The updated SWAT storage is also a great feature, and so too is the provision for longer travel dropper posts.

Really it’s the custom GENIE shock that threw the biggest curveball with its high volume, dual-stage air spring introducing a unique ride quality that’s surprised us in more ways than one. We’ve been impressed by its outstanding suppleness that makes for a luxuriously smooth ride across rocky and rooty trails. Traction is brilliant, and so too is its ability to swallow big hits and harsh landings. Bottom-out control is outrageously good, and combined with the excellent geometry and sorted build kit, the Stumpjumper offers bucketloads of confidence for ripping down technical descents.

The real magic of the GENIE shock is the way that it manages to provide such a level of cushioning in a package that retains good pop and support. You can enhance this further by adding volume bands, which is very much worth experimenting with to experience just how big of a difference it makes.

Despite its top-notch performance, some folks may still be turned off by the proprietary shock. And ultimately only time will tell how its durability fairs once there are thousands of units out there in the wild. We also can’t ignore the high starting price for the entry-level Stumpjumper Comp, though we do expect that barrier to lower once alloy models are introduced in the future.

Part of the cost comes down to the innovation that Specialized is willing to invest into developing patented technologies like the PSA air spring design. It doesn’t always make sense to do things differently, but in this case we think it’s paid off. The new Stumpjumper is a brilliant trail bike, and the GENIE shock is a big part of that brilliance.

2025 specialized stumpjumper 15 pro
With all of the suspension, geometry and wheelsize adjustments, the Specialized Stumpjumper is likely to suit a very wide range of riders.

It doesn’t always make sense to do things differently, but in this case we think it’s paid off. The new Stumpjumper is a brilliant trail bike, and the GENIE shock is a big part of that brilliance.

2025 specialized stumpjumper 15 pro
Given the advantages offered by the GENIE shock with its unique PSA air spring, we expect it’ll be coming on more Specialized mountain bikes in the future. And if the patent description is anything to go by, perhaps we’ll be seeing it in a fork too…

ABOUT THE REVIEWER - Wil Barrett

Hometown

Bendigo, Victoria

Height

175cm

Weight65kg

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