Stumpjumper

Small adjustments in shape make big differences in how a material performs. A great example of this is the shock mount at the top tube. By keeping the top tube “intact” (rather than piercing and bending it to shroud the shock, like the previous Stumpjumper), it’s more structurally sound and therefore more effective at bearing a load with less material. The flat sections of the shock mount likewise carry those loads more effectively than the curved shock mounts of the previous Stumpy. Together, this top tube/shock mount section is lighter and stiffer than its predecessor, without sacrificing durability.

Another example of how shape optimizes material use is the sidearm design. The asymmetric sidearm strut supports the shock link pivot, boosting stiffness by connecting rear end with front for a direct and integrated feel. The sidearm also prevents torsional loads from entering the top tube, which helps the bike track and handle with precision

For this all-new Stumpjumper, it started with the bike’s backbone: the frame. Control, efficiency, durability, and weight savings are all born from the frame itself. Recent breakthroughs in our carbon lab resulted in a new understanding of how shape affects a frame’s performance. Shape, not material, determines the vast majority of a frame’s weight, stiffness, and durability. Thanks to the largest Finite Element Analysis study we have ever undertaken, we’ve optimized the dimensions and radii of the Stumpy’s frame tubes and their intersections, ensuring that every fiber of carbon is delivering the most strength and stiffness it possibly can. When every piece of carbon is truly pulling its own weight, “lazy” material that would otherwise hide in unoptimized corners is totally eliminated.

One of the frame’s biggest breakthroughs came from the Flex Stay, enabling us to remove the Horst link to save weight and increase durability while mimicking the four-bar FSR system perfectly. We can manipulate the carbon fiber seatstay’s stiffness to an incredible degree, all based on how we orient the carbon fiber. The result is a tube section that can flex vertically yet be incredibly stiff laterally, recreating a pivot with our Flex Stay.

While material shape delivers the vast majority of a frame’s performance, for a bike like the Stumpjumper we coaxed every last gram of performance out of the frame. That meant utilizing the strongest, most expensive carbon we’ve ever built a mountain bike with. We selected the optimal material for every layer of carbon, all chosen to deliver the maximum performance needed in that region of the frame. This — along with our careful study of shape — is what allowed us to achieve our rider-focused performance targets with the minimum amount of material.

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