Stumpjumper 15 Review // Stumpjumper Evo Compared to the Stumpjumper 15 

The Specialized Stumpjumper was released in 1981 and was the first mass-produced mountain bike. It’s been 43 years since the original release of the Stumpjumper, and the sport has evolved exponentially. The new Stumpjumper 15 is the fifteenth iteration of the Stumpjumper and stands as a representation of just how far our relatively young sport has progressed. 

Frame Details

Specialized’s intent with the all-new Stumpjumper 15 was to create a bike that falls into the industry cliche “do-it-all” category. The Stumpjumper 15 takes the place of both the 130mm travel Stumpjumper and the more aggressive 150mm travel Stumpjumper Evo in their lineup, featuring a 150mm fork and a revised suspension platform that delivers 145mm of rear travel. The frame has a new silhouette, departing from the asymmetrical side brace of the Stumpjumper Evo while incorporating a variety of refinements throughout, such as an updated SWAT box and revised frame protection. 

The Stumpjumper 15 is available in aluminum and carbon frame construction. Both versions offer the same geometry adjustment and feature internal frame storage, with the alloy frame weighing slightly heavier than the carbon. A S4 alloy Stumpjumper 15 frame weighs 9lb, 8.0oz compared to the 6lb, 4.2oz weight of a carbon S4 frame. Both frames utilize a UDH hanger and are T-Type compatible. Alloy frames are compatible with wireless and cable-actuated drivetrains, while the carbon version is only compatible with wireless drivetrains.

Suspension 

Specialized has maintained its tried-and-true four-bar FSR suspension platform for the Stumpjumper 15 while revising its kinematics. The anti-squat of Stumpjumper 15 has been adjusted to provide what Specialized believes is the ideal balance in pedaling characteristics of the previous Stumpjumper while maintaining the all-mountain capability of the Stumpjumper Evo. At 113.5%, the anti-squat of the Stumpjumper 15 falls almost directly between that of the two previous Stumpjumper models and provides one of the most noticeable ride quality differences out on the trail. 

The leverage ratio of the Stumpjumper 15 has also been made more linear, a design choice in conjunction with the introduction of the larger volume GENIE shock. By lowering the starting point of the leverage ratio and lessening its progression, Specialized saw improvements in the consistency and control in the travel across the entirety of its range regardless of shock type when compared to the Specialized Evo. 

Geometry/Sizing

The Stumpjumper 15 is highly adjustable, utilizing the same flip-chip and interchangeable headset cups as the Stumpjumper Evo to achieve six distinct geometry settings. The overall geometry of the Stumpjumper 15 is similar to the previous Evo, with some slight variations. The wheelbase has been shortened by 3mm due to slightly shorter chainstays, and the BB is now 3mm lower. The slight refinements continue throughout the frame with a 0.4-degree slacker seat tube angle, 10mm taller headtube, and 17mm lower standover. 

In the stock Middle/High configuration, the Stumpjumper 15 maintains the same 64.5-degree head tube angle as the Stumpjumper Evo. Riders can adjust the head tube angle by 1-degree in either direction by swapping the headset cups. The flip-chip at the chainstay allows riders to adjust the head angle by another .5-degree while lowering the BB height by 7mm. Depending on its configuration, the Stumpjumper 15 can range from a 65.5-degree head angle to a slack 63-degree head tube angle.

The Stumpjumper 15 is available in Specialized’s S-Sizing. Unlike traditional sizing that offers the typical “t-shirt” sizes of SM, MD, and LG, S-Sizing offers six sizes ranging from S1 through S6. Specialized’s “style specific” sizing allows riders to pick between a range of compatible frame sizes depending on their riding style and handling preferences. At 5’10”, I’ve found that I can ride either an S3 or S4 comfortably, with each size providing distinctly different ride characteristics. The shorter reach and wheelbase of an S3 provide more maneuverability, while the larger S4 provides more stability at higher speeds.  

Mixed-Wheel Compatibility 

Size S3 - S6 Stumpjumper frames can be run as a full 29” or mixed-wheel setup. S1 and S2 frames are only compatible with 27.5” rear wheels. Frames size S3 - S6 come stock in the full 29” configuration and can be set-up mullet with an aftermarket link. 

I’ve run my Stumpjumper Evo in both configurations extensively, and while I generally prefer the full 29 setup for the majority of riding scenarios, both setups provide their own benefits. Running a smaller 27.5” rear wheel gives noticeably more clearance in steep terrain and introduces a level of maneuverability that is addictive in tight berms or rut track-like turns. The full 29” setup feels slightly more supportive and is less likely to ever feel “hung up” in rough sections of trail. 

SWAT 4.0

Specialized has updated its internal frame storage system for the Stumpjumper 15, introducing SWAT 4.0. The door and its interface have been redesigned for a more waterproof seal while eliminating any rattle. The updated SWAT 4.0 system is the most refined internal frame storage system I’ve seen to date and actuates so smoothly that it makes some other manufacturers’ attempts at frame storage feel cheaply made. 

GENIE 

“We came to this realization that bigger volume, flattening the spring curve, and making more usable travel was better.” -Chance Ferro, Specialized Suspension. 

What began as an experimental larger positive volume chamber attached to a Float X eventually became the centerpiece of the Stumpjumper 15. The Specialized GENIE shock utilizes a larger air volume than standard air shocks in an attempt to provide the ideal balance of small bump sensitivity and bottom-out resistance while offering riders a more tunable setup range than ever before. Two positive air chambers combine to increase the overall air volume in the shock, allowing for a flatter spring curve in the first 70% of the shock’s stroke. This flatter spring curve provides more sensitivity and “bump force management” in the initial and mid portions of its stroke. As the shock reaches the last 30% of its stroke, an internal band cuts off airflow from the outer positive air chamber, reducing the overall air volume and increasing the progression of the spring rate. This design provides an air shock that tracks terrain with ease throughout the mid-stroke while providing an increase in bottom-out support towards the end of its stroke. 

The highly adjustable nature of the GENIE shock allows riders to fine-tune the mid-stoke and end-stroke support via volume spacers. The outer sleeve of the GENIE can be removed to add up to four spacers. Additional spacers can be added to the internal positive chamber to provide a noticeable increase in end-stroke support. Adding the GENIE's band-style volume spacers is relatively easy, only requiring a small flathead screwdriver to undo the c-clip. 

Riding Impressions / Running a RockShox Vivid on the Stumpjumper 15

A Specialized Evo equipped with a RockShox Vivid air shock has been my daily ride for the past two years. I have entrusted it to navigate everything from local after work laps to rock-riddle Whistler tech, that left me wondering if a half-shell helmet was the best choice. I jumped at the opportunity to test a Vivid-equipped Stumpjumper 15 to discern the finer differences between the two frames. 

My settings with the Vivid installed were nearly identical to those of the Vivid on my Evo, only running a bit more compression damping for added mid-stroke support. The Vivid’s sensitive initial feeling of its TouchDown damper paired with the tunable Hydraulic Bottom Out delivers a ride quality that tracks chattery terrain exceptionally well and offers support on big impacts. While the GENIE and the Vivid are two different approaches of a larger volume shock, they both feel at home on this frame. In its stock configuration, the GENIE has an extremely plush and active feeling throughout the first 70% of its stroke. The GENIE offers riders a wide range of adjustability with volume reducers but doesn’t offer any type of compression adjustment, making the Vivid an attractive option for riders wanting to tune in additional compression damping. 

Climbing

While the Stumpjumper Evo isn’t a horrible climber, the Stumpjumper 15 does provide a slightly more supportive feeling under power, and it easily maintains traction over roots and rock-riddled sections of trail. The Stumpjumper 15 seemingly has a bit more pep in its step, encouraging riders to zip in and out of tight switchbacks with more liveliness than the Evo. 

The pedaling position of the Stumpjumper Evo was already comfortable, but the 0.4-degree slacker head tube angle of the Stumpjumper 15 doesn’t seem to negatively impact the climbing position an unforgivable amount. On steeper, technical climbing trails I was still able to properly weight the front wheel and the rear suspension tracked the ground well. This ground-hugging ride quality when climbing is especially pronounced when running a GENIE shock with its stock configuration.

Descending

Specialized has marketed the Stumpjumper 15 as a replacement for both the Stumpjumper and Stumpjumper Evo, although its capabilities and descending performance lean more towards that of the Evo. Riders familiar with Stumpjumper Evo will get along well with the new model. While the Stumpjumper 15 has 5mm less rear travel and a 10mm smaller fork, its revised kinematics provide a ride quality that is seemingly even more capable. I never noticed the 5mm difference in rear travel when descending; if anything, the updated kinematics provided a bit more of a bottomless feeling. On larger drops or harsh impacts, the Stumpjumper 15 provides a plush but supportive quality that I have previously associated with bikes in the 160mm enduro category. Compared to the Evo, the Stumpjumper 15 also feels more active in its travel, remaining planted over repeated impacts. 

While Specialized has provided riders with a range of geometry adjustments, I prefer the stock Middle/High setting on both the Stumpjumper Evo and Stumpjumper 15. The lower BB position and 0.5-degree slacker head tube angle of the Low position are great in the bike park, but I’ve found that the increased crank clearance and 64.5-degree head tube angle of the High position are better suited for most scenarios. 

The Stumpjumper 15 rewards riders who look to generate speed by pumping the bike through natural compressions instead of blindly charging at anything in their path. The ride characteristics of the Stumpjumper 15 are generally more lively than the Evo’s. Regardless of which shock I was running, the Stumpjumper 15 was extremely active throughout the first two-thirds of its stroke, maintaining its composure through repetitive impacts and chattery sections of the trail. The bike outperforms it's 145mm travel number in rougher terrain and always has a bit of extra support on hand for the occasional huck-to-flat. I would summarize the ride quality of the Stumpjumper as “comfortably composed.” Whether I was on a meandering section of singletrack or a downhill track that warranted a full-face helmet, the active suspension of Stumpjumper 15 provided a ride quality that was as predictable as it is capable. 

Verdict 

The Stumpjumper Evo was affectionately referred to as the “Goldilocks” bike by some for its comfortable riding position, wide range of adjustment, and balance of climbing efficiency and descending capability. The Stumpjumper 15 strikes this same “just right” feeling on the trail. Its stock geometry and suspension are capable enough for first-time riders and experts alike. The wide range of adjustments allows riders to tailor the bike to suit their preferences. Stumpjumper Evo riders shouldn’t feel like their bike is completely obsolete with the introduction of the Stumpjumper 15, although Specialized has introduced a range of refinements that are noticeable out on the trail.