FIRST RIDE REVIEW

THE NEW SPECIALIZED STUMPJUMPER 15

ONE BIKE TO DO IT ALL?

Words by Robert Johnston  |  Photos by Specialized / Rodrigo Vicente

The Specialized Stumpjumper was the original production mountain bike, hitting the market some 43 years ago. Since then, it has remained a key bike in the Specialized lineup, and has continued to represent the modern standard for a trail mountain bike with every new iteration. For generation 15 of the full suspension Stumpjumper, the looks remain every bit “Stumpy”, but thanks to some new tech and refinement throughout, performance has kicked up a notch once again.

ABOUT THE SPECIALIZED STUMPJUMPER 15

ONE STUMPJUMPER TO SUIT ALL | For the Stumpjumper 15, Specialized wanted to simplify the answer to “which trail bike do I need?” Rather than offering distinct Stumpjumper and Stumpjumper EVO models, they instead focused on one frame that can deliver both the well-rounded trail bike nature of the standard Stumpjumper and the enhanced capability of the previous EVO. This has been achieved through the use of their new patented GENIE air spring technology, as well as comprehensive geometry adjustability. Combining the two, the rider is able to transform the handling of the bike without changing any components.

The new Stumpjumper 15 features a 145mm FSR rear end, which is paired to a 150mm fork as standard. In the S1-S6 size range, S1 and S2 sport MX wheels only, whereas S3 and up can be equipped with either MX or dual-29” wheels. Switching between MX and 29 requires the purchase of a new link, which maintains the geometry between each wheel size.

Further adjustments to the geometry are retained from the Stumpy EVO, with an adjustable headset cup offering one degree of adjustment in either direction, and a flip chip in the Horst link offering a High and Low BB setting.

The Stumpjumper 15 carbon is manufactured from their FACT 11M carbon fiber. This frame loses the sidearm design, but Specialized was still able to add a small amount of stiffness without a weight penalty. Retained is the SWAT downtube storage, with a new SWAT 4.0 design that is easier to operate and better equipped to deal with the elements.

Specialized covers the details well with a generous downtube cover; rubber chain and seat stay protectors, and a small mud flap on the lower pivot. There’s ample room for a large water bottle inside the front triangle across the size range, and the included bottle cage features their SWAT tool for quick access for trailside repairs. Cable routing is fully guided internally for dropper post and rear brake. Interestingly, there are no provisions made to route a mechanical drivetrain – the new Stumpjumper is designed for wireless drivetrains only.

Rounding out a packed features list is Specialized’s lifetime bearings guarantee. Specialized will replace the frame pivot bearings for free for the duration of ownership for the first owner, reducing maintenance costs down the line when they inevitably wear out.

THE NEW GENIE AIR SPRING TECHNOLOGY | The biggest talking point of the new Specialized Stumpjumper 15 is the patent-pending GENIE air spring technology in the rear shock, developed in collaboration with Fox. This technology helps to deliver the best performance out of the 145mm FSR rear end, while offering some transformative tuning capabilities to obtain the trail feel that every rider desires.

In essence, GENIE is a two-stage air spring. From zero to 70% travel, the shock features a large air volume thanks to a standard inner chamber combined with a voluminous outer air sleeve. This lets the shock deliver a more supple, linear “coil-like” spring curve. Once the shock reaches 70% travel, the GENIE band (a sliding bushing) closes off the large outer air sleeve, leaving only the inner air chamber volume. This delivers a pronounced ramp up of progression towards the end of the stroke, without compromising the earlier stages of travel.

The volume of the outer air sleeve can be tuned by adding up to four volume reducing bands, letting you tweak the feeling of the main portion of the stroke. With no volume reducers it’s ultra-plush, and adding bands delivers a progressively more supportive and sporty feeling. The inner chamber volume can also be tuned to tweak how much progression the final portion of the travel has.

Specialized has made some big claims about the resulting performance of the new GENIE-equipped Stumpjumper 15. They state 57% increased traction, and 16.3% better big-hit performance than the outgoing Stumpjumper EVO. These are big claims, but the on-trail feel delivered from our initial two days testing the Stumpjumper 15 haven’t left us doubting them.

STUMPJUMPER GEOMETRY | Specialized didn’t go crazy with the geometry on the Stumpjumper 15. Recognizing that many riders still seek an agile do-it-all trail bike, the stock geometry is well rounded and doesn’t succumb to much of the typical lower-longer-slacker treatment.

With the reach-based “S” sizing system combined with large adjustment potential, most riders should be able to obtain the fitment and trail character they desire. 25mm gaps between sizes should let most riders get close to their optimum cockpit fit.

The adjustability of the headset and flip chip can take the stock 64.5° head tube angle to a raked-out 63° or more agile 65.5°. Bottom bracket heights are low across the board, with a 337mm stock height giving great rider integration. However, some riders in particularly chunky areas may struggle for pedal clearance.

BUILD SPECS | AT TIME OF LAUNCH

STUMPJUMPER 15 OHLINS COIL

MSRP: $8,500 | €8,500 | £6,500

STUMPJUMPER 15 EXPERT

MSRP: $6,500 | €7,500 | £5,500

STUMPJUMPER 15 PRO

MSRP: $9,000 | €9,500 | £7,000

S-WORKS STUMPJUMPER 15

MSRP: $12,000 | €13,000 | £9,000

S-WORKS STUMPJUMPER 15 FRAMESET

MSRP: $3,500 | €4,500 | £4,000

THE DIRT

I had the opportunity to put the new Specialized Stumpjumper 15 to the test over a couple of days on Mt Tzouhalem in BC, Canada. With a variety of trails to test performance both up and down the hill, it offered the perfect testing ground to quickly become familiar with the latest generation of their do-everything trail bike.

SETUP ON THE STUMPJUMPER 15 | With all of the adjustability built into the new Stumpjumper comes a huge range of setup options. I began by leaving the headset in the neutral position; BB in “high” and the GENIE shock in the stock 1-band volume spacer configuration. With rear shock sag set to 16mm (30%), and my go-to Fox 36 setup, I was immediately comfortable and ready to hit the trails without any setup trickery.

The first day of riding was done without any information on the new Stumpjumper or what was happening inside the GENIE shock. We were instructed to simply ride and get a feel for both bike and terrain. Trying to balance the bike somewhat blindly, the rear end stood out for its supple initial stroke combined with an inability to bottom out. This led me to slightly reducing pressure in the fork and adding a volume reducer, hoping to get it to match the rear end’s feelings of capability and traction. Once I was comfortable that I’d dialed-in the suspension setup for the terrain, I decided to see just how capable I could make the Stumpjumper. I first swapped to the low BB setting, did a couple of runs, then switched to the slack headset cup setting. In an ideal world I would have swapped out for a gravity rear tire too, but these were unavailable.

On day two and following Specialized’s presentation on the new Stumpjumper and the GENIE tech, we were taken through a bracketing procedure for the rear shock. We began with a warm up lap on the stock shock configuration to refamiliarize with the bike and trails. We then packed the air sleeve full of the maximum four volume reducers and repeated the run. Finally, we removed all volume reducers and rode the same trail once more. With the same sag and damper setup, we were quickly able to feel the difference in character that these volume reducers produced, and it was profound.

CLIMBING | In all configurations, the Stumpjumper 15 was a solid climbing machine. The suspension platform struck a nice balance between comfort and traction and efficiency, but certainly wasn’t the firmest out there. Riders looking to cover big miles on smooth climbs would benefit from using the easily accessible lockout lever to boost efficiency. With the maximum volume reducers in the outer air sleeve of the GENIE shock, pedaling efficiency received a slight boost that some riders would appreciate.

The geometry on the new Stumpjumper made for a well-rounded climber. The Actual Seat Tube angle is slack, so riders like myself with disproportionately long legs will receive a slacker Effective Seat Tube angle than the quoted 77 degrees. But even still, pushing the saddle forward on the rails ensured I faced no issues.

The only complaint that some riders may have with the climbing performance on the Stumpjumper would be its lack of pedal clearance on the chunkiest ascents. The bottom bracket is low, even in the highest possible configuration. This comes with some benefits on the way down the hill, but may require those in particularly chunky areas to up-travel the fork; run less sag or fit shorter crank arms. Or all three, if you live for climbing up rock-littered terrain.

DESCENDING | The Stumpjumper 15’s adjustability easily encapsulated the standard Stumpjumper and Stumpjumper EVO of the previous generation. With four volume reducers in the GENIE air sleeve, the reactive and snappy feeling of the previous Stumpjumper was closely matched, if not exceeded. This made for a pleasurable time on the smoother sections of Tzouhalem’s flow trails. Quick direction changes were made with ease and the terrain could be worked hard for speed with great results.

Taking the Specialized Stumpjumper 15 up to an EVO-style setup, with maximum sensitivity in the rear shock and the slackest and lowest geometry configuration, its capabilities were seriously impressive. The stability and reassuring precision of the package were a delight to push hard, pulling for gaps and sticking ambitious lines. Enough confidence was delivered by the big-hit capabilities of the GENIE-equipped rear end to drop into a double black diamond trail without a second thought. Though it was far from the gnarliest trail in BC, the ladder drops and step downs of the Loam Line would have your typical trail bike thinking twice. But the new Stumpy offered a reassuring feel that let me press send, and took it all in its stride.

THE WOLF’S FIRST IMPRESSION

Though the capabilities are impressive on the new Specialized Stumpjumper 15, it’s the adjustability of both geometry and suspension feel that have been the stand-out in the first couple of days testing. Going anywhere from a well-mannered mile muncher to a bikepark-friendly ripper with a couple of tools and ten minutes of your time is awesome, and I’m seriously looking forward to welcoming one in for its long-term review.

Price Range:
$6,500 /£5,500 /€7,500 (Expert) – $12,000 /£9,000 /€13,000 (S-Works)

Website: Specialized.com