Specialized launched the first Stumpjumper 43 years ago and it became the flagship of the US cult brand. A lot has changed visually and technically between 1981 and today. And even now, the model has grown again. Although only slightly changed visually, the bike is clearly recognizable as a Stumpjumper at first glance. When it comes to the inner values, Specialized reveals more significant changes.

Genie, the "ghost in the shock"

The new suspension is said to absorb impacts up to 16.3 percent better than the current Stumpjumper Evo. The loss of traction time has also been reduced by 57 percent in the same comparison and punctures are said to have 39 percent less impact on the rider and material.

Behind these impressive figures is "genius". This is not the genie from the bottle as we know it from fairy tales. Genie is Specialized's new technology, which combines the best properties of a steel spring with those of an air spring in a new type of air shock: an extremely fine response and soft characteristics in the upper travel range paired with better adjustability, better performance on hard impacts and lower weight. Genie seems to fulfill almost every wish for a suspension system.

The Genie air shock is divided into two separate positive air chambers that are connected via channels. As a result, it offers a larger air volume over the first 70 percent of the spring travel, which is similar to the soft characterization of a steel spring damper. If the rear suspension compresses above this threshold value, the special Genie band closes the openings to the outer air chamber, thus reducing the air volume and reacting much more progressively in the last 30 percent of the suspension travel. This in turn significantly increases bottom-out protection and supports an active riding style.

Frame, geometry and details

The new Stumpjumper frame has been designed with a certain amount of flex. As such, the 15th generation of this cult bike doesn't simply shine with the highest stiffness values. Based on the idea that a bike should adapt to the terrain and not the other way around, Specialized made the frame from FACT-11M carbon and M5 aluminium. Thanks to the targeted use of these materials, the bike forms a single unit from front to back with perfect stiffness ratios.

The SWAT™ box is once again part of the frame. In its fourth generation, the smuggling compartment in the down tube is designed to be even safer and better integrated while keeping its contents protected from external influences.

The geometry of the Stumpjumper 15 combines a smooth ride, agility and efficient climbing capabilities. The rider is positioned centrally for the best possible traction and cornering control. The low bottom bracket, the flat head tube angle and the optimized fork offset contribute to the smooth ride even when riding aggressively.

Three different rear triangle dimensions depending on the rider's frame and body size further optimize handling. According to S-sizing, a person of 173 centimetres can also ride frame sizes between S2 and S4 (similar to sizes S to L) depending on their own preferences. The Stumpjumper 15 also offers six individual settings. The steering angle can be adjusted between 63 and 65.5 degrees in three positions via the eccentrically shaped upper headset shell, while the bottom bracket can be moved seven millimetres up or down by rotating the Horst-Link FlipChips by 180 degrees. This allows you to optimize the centre of gravity or increase ground clearance, for example. The Stumpjumper can also be ridden as a twentyniner or with an MX setup (27.5-inch rear, 29-inch front wheel).

The Stumpjumper 15 is available in sizes S1 to S6 and in the S-Works, Pro, Expert and Comp versions, as well as a model with Öhlins suspension. For fans of individual equipment, Specialized also offers S-Works frame kits.

specialized.com