Since 1974, the Specialized Stumpjumper has been the benchmark in mountain biking.

For 2025, the latest iteration - the Stumpjumper 15 - continues this tradition with a host of modern advancements. In this article we explore the significant updates to the 15th generation of Stumpjumper, and compare it to it's predecessors: the previous generation Stumpjumper and Stumpjumper EVO.

The Fox GENIE shock is the heart of the new Stumpjumper 15, featuring a huge air volume for a coil-like feel, combined with the end stroke ramp-up and tunability of an air shock.

Key Updates in the all-new 2025 Stumpjumper 15

1. GENIE Shock Technology: At the heart of the Stumpjumper 15 is the GENIE shock, developed by Specialized with Fox. Essentially a Fox Float with an additional air sleeve, the GENIE features a huge air volume for the first 70% of travel, providing a plush, coil-like feel. At the 70% mark, the GENIE band automatically cuts off the outer sleeve, drastically reducing air volume and creating a more progressive spring rate for the final 30% of the stroke. This design effectively functions like a volume spacer at the end of the stroke but maintains the plushness and sensitivity throughout most of the travel. The GENIE combines some of the best aspects of both coil and air shocks, meaning you can have your cake and eat it too.

2. Updated FSR Suspension: Alongside the revolutionary new GENIE shock, the Stumpjumper 15 boasts an updated FSR suspension linkage system, tuned to offer better bump absorption and ground tracking. This latest version features a more progressive leverage ratio that enhances both off-the-top plushness and bottom-out resistance. Riders can expect improved comfort and control on rowdy trails, setting the Stumpjumper 15 apart from its predecessors.

3. Weight Reduction: The side-arm is gone. Thanks to new construction materials and techniques, the Stumpjumper 15 frame is lighter than both the previous Stumpjumper and the Stumpjumper EVO. Utilising Specialized's FACT 11m carbon fibre, the new frame is not only more responsive but also maintains durability. This reduction in weight enhances climbing efficiency and manoeuvrability, making the Stumpjumper 15 more agile and playful on the trail. Imagine the lightweight handling of the previous Stumpjumper, with the suspension performance of the EVO.

4. Modern Geometry: The 2025 model introduces a revised geometry that favours stability and agility. Compared to the previous generation Stumpjumper, the Stumpjumper 15 features a slacker head angle and a longer wheelbase, providing increased stability on descents and improved handling on technical sections. The lower bottom bracket height further enhances cornering performance, a notable improvement from both the standard Stumpjumper and the EVO. The Stumpjumper 15 also features a deeper max seatpost insertion depth allowing you to run a longer travel dropper.

5. Aesthetics and Ergonomics: The 2025 Stumpjumper 15 features a modernised frame design with integrated cable routing, improving both aesthetics and maintenance. Ergonomic refinements, such as an upgraded saddle and grips, enhance comfort for long rides, making it more user-friendly compared to the previous models. Keep in mind that the carbon Stumpjumper 15 only has routing for electronic (AXS) shifting - the alloy model features provision for cable shifting.

Comparison to Previous Generations

Stumpjumper 14 EVO vs. Stumpjumper 15:

The Stumpjumper EVO was designed with a focus on aggressive trail riding, offering a more rugged build and slack geometry compared to the standard Stumpjumper. While the EVO excelled in downhill stability and rough terrain performance, the Stumpjumper 15 brings advancements that blend the strengths of both models. The new Stumpjumper 15 combines the EVO’s stability with improved weight efficiency and a refined suspension system, making it a more versatile choice.

While the Fox GENIE shock was designed in parallel with the new bike, the Stumpjumper 15 is 100% compatible with any standard 210 x 55mm shock. The Specialized Enduro team is racing the Stumpjumper 15 on the Enduro World Cup circuit, with the riders choosing the Rockshox Super Deluxe coil and air shocks depending on their preference.

Stumpjumper 14 vs. Stumpjumper 15:

The standard Stumpjumper from the previous generation was praised for its super light weight, well-balanced ride and solid build, but it lacked the suspension confidence delivered by it's longer travel sibling. The Stumpjumper 15’s improved suspension system and updated geometry deliver a noticeable improvement in performance, particularly on fast and steep, technical trails.

A hard earned thirst: The Stumpjumper 15 Pro features a textured "splatter" finish that looks like a cold beer pulled from the eski on a hot day.

Conclusion

The Specialized Stumpjumper 15 represents a significant leap forward from both the standard Stumpjumper and the Stumpjumper EVO. With its improved suspension performance, reduced weight, and modern geometry, the Stumpjumper 15 offers superior performance and versatility. For riders seeking a trail bike that excels in a range of conditions while maintaining cutting-edge technology, the Stumpjumper 15 is a compelling choice that builds on the legacy of its predecessors with notable improvements.

Pros and Cons: Stumpjumper 15