​Specialized Stumpjumper 15 Long-Term Review

Specialized hadn’t given the Stumpjumper platform a significant update over the last few years, mainly because it was a tried-and-true platform that was loved by many around the world. Between the standard 130mm-travel and 150mm-travel EVO models, it was a bike that could ride a wide variety of trails and terrain with poise, including an Enduro World Cup win under Specialized Factory Team rider Charlie Murray.

However, after over three years of development by the 50-person-strong Specialized Ride Dynamics team, the 15th iteration of the Stumpjumper is here. The goal? To further refine and highlight the positive attributes of the previous platform while minimizing or eliminating the negative traits. The geometry of the new bike isn’t revolutionary, but the Stumpjumper is now consolidated into a single 145mm-travel family with a healthy dose of new tech that aims to be the ultimate quiver-killer.

FRAME

Like the previous Stumpjumper, the new platform prioritizes integrated frame adjustability. A flip chip at the Horst Link lets the bottom bracket height be fine-tuned by +/- 7mm to give you a bit more clearance on techy trails or more stability when speeds pick up, but the rest of the geometry remains the same. Size S1 and S2 frames come with a mixed-wheel setup, while S3–S6 frames have 29-inch wheels. However, an aftermarket link kit allows the bike to run either configuration without altering the geometry.

There are also adjustable headset cups, which let the Stumpjumper 15 be a nimble trail weapon with a 65.5-degree head tube angle, a descent-hungry machine with a 63-degree head tube angle, or a versatile and more balanced platform with a 64.5-degree head tube angle. Cable routing for the brakes and dropper post are run internally through the side of the head tube, but the carbon-framed Stumpjumper lacks routing or the ability to run a mechanical drivetrain.

Looking at the geometry numbers, there have been some subtle but effective tweaks to unlock even more descending prowess from the platform. As we mentioned above, the head tube angle is 64.5 degrees with the neutral headset cup installed, and the effective seat tube angle sits between 75.8 degrees and 76.7 degrees on our S4 frame. Stack height and head tube length are taller than the previous Stumpjumper at 640mm and 125mm respectively, and the bottom bracket height sits at 330mm or 337mm depending on the flip chip setting. Chainstays are also size-specific and sit at 435mm or 441mm on our S4 frame, and the wheelbase sits at 1,244mm or 1,252mm.

Finishing off the frame is the latest iteration of the Specialized SWAT downtube storage system, which features a more low-profile lid that is flush with the downtube and has a larger actuation lever. It also has improved weather sealing to prevent water, dirt and other debris from entering the frame.

SUSPENSION

Gone is the asymmetric sidearm design that was synonymous with the previous Stumpjumper, but it still uses Specialized’s FSR suspension design in a four-bar layout with a yoke driving the rear shock. Though the suspension design is essentially the same, the leverage curve now has a lower starting point and is more linear, which Specialized says improves consistency and control across the range of travel regardless of shock type. The anti-squat sits at roughly 105 percent at sag and drops down to just under 78 percent as you progress into the end of the travel, and the axle path is approximately the same as the outgoing model.

Perhaps the biggest technological advancement with the 15th generation of the Stumpjumper is the all-new Genie rear shock, developed between the Specialized Ride Dynamics team and engineers at Fox Suspension. Put simply, the Genie shock uses a larger-volume outer sleeve, dubbed the Extra Volume (EV) chamber, in conjunction with a smaller-volume internal chamber to uniquely blend small-bump sensitivity in the first 70 percent of the travel with a progressive ramp-up in the last 30 percent to prevent bottoming out. The outer and inner air chambers use separate volume spacers, so it’s possible to tune the beginning and end of the stroke independently to get your desired feel.

The Genie shock is based on the stock Fox Float shock and uses many of the same internals, so service parts are widely available. There are three preset compression settings—plush, neutral and firm—and 14 clicks of low-speed rebound adjustment. Specialized recommends running the Genie shock with 16mm (30 percent) of sag. Our test bike had the factory version of the shock paired with a 150mm Fox Factory 36 fork with their descent-focused GRIP X2 damper.

COMPONENTS

Specialized offers five different carbon-framed complete builds of the Stumpjumper 15, along with a bespoke S-Works frameset for $3500. They range in price from $5500 for the Comp build with SRAM S1000 Transmission and Fox Performance suspension to $12,000 for the top-spec S-Works build with XX Transmission, Maven Ultimate brakes and Kashima-coated Fox Factory suspension. They also have a coil-equipped build that uses an Öhlins RXF38 M.2 fork and TTX 22 M shock for a more freeride-focused platform.

We tested the Pro build of the new Stumpjumper, which is the next step down from the S-Works build and is centered around a high-end yet durable parts spec. SRAM’s tried-and-true X0 Transmission worked flawlessly out of the box, and the Roval Traverse SL II carbon rims laced to Industry Nine 1/1 hubs were stiff and lightweight, yet held up to whatever abuse we could throw at them. The wheels were wrapped in a Specialized Butcher/Eliminator 29×2.3-inch tire combo, both of which are built using a Grid Trail casing and T9/T7 compound.

A powerful set of SRAM Maven Silver brakes brought our test bike to a halt and were paired to 200mm/200mm HS2 rotors. Some riders thought the 200mm rotors were a bit overkill for the lightweight all-mountain bike and felt 180mm rotors would’ve made the power a bit more accessible, but they still worked very well.

Looking at the cockpit, our test bike was spec’d with an Industry Nine 40mm stem and Roval Traverse SL carbon handlebars with 30mm of rise wrapped in Deity Lockjaw grips, a personal favorite for several of our test riders. A BikeYoke Revive Max dropper post with 185mm of drop felt a bit short for the S4 frame (more on that later), but mechanically it worked flawlessly. The Specialized Bridge Expert saddle was also comfortable and gave us a good balance of cushion and support.

CLIMBING

Climbing on board the Stumpjumper 15 is a welcome, no-fuss experience. Looking at the cockpit and rider compartment, the 76.5-degree seat tube angle and 475mm reach felt near perfect and put our test riders in a neutral, balanced position to put down power. The vast majority of our time was spent with the headset in the neutral position with a 64.5-degree head tube angle, which felt spot-on and gave us a familiar, intuitive feel when navigating tight corners and technical climbs. The steeper setting gave the bike slightly quicker handling and made it a tad more responsive, but nothing that was too radical. If you’re constantly climbing technical trails with lots of rocks and roots, the steeper head tube angle may be advantageous. We didn’t feel much of a discernible difference in climbing performance with the headset in the slacker setting, and we still felt like the bike wanted to hold a straight line without any additional wheel flop. The anti-squat also felt ideal at approximately 108 percent at sag, giving us a harmonious blend of traction and efficiency.

We were thoroughly impressed with the Genie shock’s performance while putting down power. Small bumps, rocks and roots seemed to disappear, yet it was incredibly supportive and gave the bike a snappy and sporty personality. At just over 30 pounds, it’s about average in the weight department for trail/all-mountain bikes, but it pedals with the efficiency of something with less travel and weight. It’s eager to jump forward with each pedal stroke and doesn’t shy away from technical climbs where power and precision are a priority. The suppleness off the top gave the rear tire tons of grip in a variety of conditions and terrain, but it never wallowed or sunk too deep into its travel. We spent most of our time with the two-position switch in the Open position; we only felt the need to lock out the rear shock on smooth fire or logging roads.

DESCENDING

The Stumpjumper 15 really shined when the trail pointed back down. It feels like the point-and-plow attributes of the Specialized Enduro platform were blended with the lively and playful characteristics of the new Epic 8 EVO. The Genie shock, with its dual-chamber design, gives the bike incredible small-bump sensitivity and a noticeable improvement in grip, especially on high-speed sections. The back wheel seemed to hug the ground more and let us push through sections with traction and confidence that we otherwise might back off in, yet it still felt poppy and playful when we wanted it to be. Especially through braking bumps, the bike felt settled and composed, like it wanted to hold its line instead of getting bounced around.

Heavy impacts, big drops, and bike-park-sized jumps were also handled with surprising poise and composure. On impacts that we thought would blow through the bike’s travel, the Genie shock smoothly ramped up and handled them without a second thought.

The descent-focused fork with Fox’s new GRIP X2 damper works very well and gives us a useful range of damping and support to work with while soaking up almost anything we could throw at it. We found that the stock setup consisting of a single spacer in the outer sleeve and the 0.2-inch spacer in the inner chamber was ideal for the majority of our riding. Test riders experimented with adding spacers in both chambers, but the consensus was that the stock spacer setup gave us the most access to the travel and the best overall feel.

The SRAM Maven Silver brakes and HS2 rotors are another standout on rough, rowdy, and high-speed trails. They display outstanding heat management on long descents without fading, and stopping power is available in excess. The Roval Traverse SL II carbon wheels were very stiff and felt quick to accelerate when throwing in pedal strokes, but they were still compliant and predictable when pushing through corners. They held up to our abuse without a whimper and remained true throughout our testing period.

WHAT DID WE LOVE?

Despite being new proprietary technology, the Genie shock felt excellent and worked without fault throughout our testing period. Initial setup and setting sag was easy and simple, and the included volume spacers allowed us to easily and effectively tune both the large and small air chambers independently. The GRIP X2-equipped Fox 36 fork also worked very well and gave us a wide range of meaningful compression adjustments.

SRAM’s Maven brakes gave us more stopping power and heat management than we could ask for and let us bring the bike to a halt on a dime, and the Stealth levers made a subtle difference in making the cockpit more tidy. The Roval Traverse SL carbon wheels also felt stiff and lightweight, and were durable enough for rough and rowdy trails.

WHAT DID WE HATE?

For most of our test riders, the 185mm dropper post on the S4 frame was a bit too short and had to be raised significantly above the collar to get the saddle at the right height. Size S5 and S6 frames have a 213mm dropper, and we would’ve preferred the S4 to have one as well.

The contact point on the Maven Silver brakes was occasionally inconsistent as well; it felt like they would pump up and go from requiring more pull to being much more sensitive. There was no shortage of stopping power, but the application of that power was just vague at times.

We also feel the need to mention the lack of drivetrain cable routing. SRAM’s wireless options are becoming more ubiquitous and accessible in price point, but there’s still a large contingent of riders who are loyal to mechanically driven drivetrains and are excluded from the carbon-framed Stumpjumper family.

BOTTOM LINE

Overall, we’re impressed with the new Stumpjumper 15. It’s eager to climb just about anything you can power up with comfort and efficiency, yet it descends like a bike with more than 145mm of rear travel.

Even though it can handle rough and rowdy trails and big drops with confidence, it still rides like a true trail bike when you want it to be, and can pop and manual its way through almost anything.

It feels like a side-hit hunter and a plow-hungry machine at the same time. If you want a platform to keep your stable small and something to cover virtually all of your bases, the Stumpjumper 15 might be the ticket.

SPECIALIZED STUMPJUMPER 15 PRO

www.specialized.com

CATEGORY: All-mountain

WHEEL SIZE: 29″

SUSPENSION: 150mm (front), 145mm (rear)

Price: $9000
Weight: 30.4 pounds (without pedals)
Sizes: S1, S2, S3, S4 (tested), S5, S6
Frame tested: FACT 11m carbon fiber (145mm)
Shock: Fox Float Factory w/ Specialized Genie (210x55mm)
Fork: Fox 36 Factory GRIP X2
Wheelset: Roval Traverse SL II (hookless carbon), Industry 9 1/1 hubs

Tires: Specialized Butcher GRID TRAIL T9 (29”x2.3”), Eliminator Grid Trail T7 (29”x2.3”)

Seatpost: BikeYoke Revive Max, 185mm travel
Saddle: Specialized Bridge Expert
Handlebar: Roval Traverse SL carbon 35 (800mm)
Stem: Industry 9, 40mm length
Grips: Deity Lockjaw
Headset: Specialized angle adjust
Brakes: SRAM Maven Silver
Rotors: SRAM HS2 200mm (front)/200mm (rear)
Rear derailleur: SRAM X0 Transmission
Shifters: SRAM AXS Pod Controller
Crankset: SRAM X0 Eagle, integrated guard
Bottom bracket: SRAM DUB Wide BSA 73mm
Cassette: SRAM X0 Eagle T-Type 12-speed, 10-52T
Chain: SRAM XO Eagle T-Type
Chainrings: SRAM X0 T-Type 32-tooth

GEOMETRY SIZE S4

Head tube angle: 63.5°–65.5°
Effective seat tube angle: 75.8°–76.7°
Reach: 475mm (18.7”)
Stack: 640mm (25.19”)
Bottom bracket height: 330mm–337mm (12.99”–13.27”)
Chainstay length: 435mm–441mm (17.13”–17.36”)
Wheelbase: 1240mm–1252mm (48.82”–49.29”)