Mountain Gear

Specialized Stumpjumper — the lightest ever — rips the trails again

Specialized completely overhauls one of the most venerable mountain bike models, with alloy or carbon models to flatten trails and singletrack.

The Specialized Stumpjumper franchise has a relatively long history in the world of mountain bikes, dating back to the early 1980s. For 2021, the venerable line of cross country bikes just got a complete overhaul.

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2021 Specialized S-Works Stumpjumper
2021 Specialized S-Works Stumpjumper Photo: Specialized

The 2021 Stumpjumper features Specialized’s trail geometry and in-house developed Rider-First Engineering — which should deliver an ideal balance of tuned stiffness, weight, and ride quality in each of the six offered sizes. The “Stumpy” promises a lightweight bike that should rip up hills and shred down them, with the promise of ease and control.

Customizable geometry

2021 Specialized Stumpjumper geometry high setting.
2021 Specialized Stumpjumper geometry low setting.

Specialized says that the Progressive Geometry of the Stumpjumper is long, low, and slack, with a short offset fork and a relatively steeper seat tube angle. The flip-chip design allows you to tune the geometry — adjusting the bottom bracket height by 7mm and head tube angle by half a degree — to suit your mood and riding needs. Specialized notes that a lower bottom bracket and slack head tube angle with reduced fork offset while increasing stability.

The 2021 Specialized Stumpjumper features a flip chip to allow for customizable geometry.
The 2021 Specialized Stumpjumper features a flip-chip to allow for customizable geometry. Photo: Specialized

The pivotless seatstay/chainstay on the Stumpjumper — that is, no mechanical pivot point — allowed Specialized to drop 55g of hardware while improving lateral chassis stiffness, and hopefully reduce time in the stand for maintenance. The other net effect of this design is up to 130mm of travel without any pivot hardware or redundant material required for bonding pivot parts.

2021 Specialized Stumpjumper leverage curve.

The Stumpjumper’s progressive leverage offers a steep slope — in other words,  a good platform to pedal against through the mid-stroke, and improved bottoming resistance at the end of the stroke. Specialized says the result of this profile is, “a snappy ride for the first two-thirds of travel, then — thanks to an increased spring rate — excellent bump force management and resistance to bottoming.”

The Morgan Hill, California-designed Stumpjumper was created with a size-specific approach to ride characteristics to ensure superb handling and flawless performance for this 2.25-kilogram frame (Specialized notes this is for the painted S-Works model, S-3 size with rear shock). Engineers at the Big Red S also say that this frame is more than 100 grams lighter than the previous Stumpjumper chassis.

2021 Specialized Stumpjumper alloy
Photo: Specialized
2021 Specialized Stumpjumper alloy
2021 Specialized Stumpjumper alloy. Photo: Specialized

The S-Works Stumpjumper frame is fabricated from the same carbon used in the super lightweight Aethos road bike. The bike’s FACT 11m carbon chassis and symmetrical rear-end was designed around 29-inch wheels.

The Stumpjumper features a SWAT door in the frame — a detail Specialized has included since the reintroduction of the Stumpjumper in 2016 — to stow what the brand refers to as “oh-shit” necessities, like pumps, CO2 cartridges,  and tubes. The SWAT Bladder has an extra 22oz of water storage capacity hidden in the downtube, so you’re less likely to run dry when going long between refills.

Of course, fully enclosed internal cable routing makes this bike look clean before you get it dirty.

The 2021 Specialized Stumpjumper comes in build packages across a range of price points, from the sub $10,000 super-lightweight S-Works model, to the Stumpjumper Alloy with a SRAM SX 12-speed groupset that’s a little easier on one’s checking account. The S-Works frame is also available standalone, with a Fox Float DPS Factory shock.

2021 Specialized Stumpjumper expert. Photo: Specialized

2021 Specialized Stumpjumper Evo

Trail riding? Check out the Specialized Stumpjumper Evo, for which Specialized says this bike was specifically designed. The Stumpy Evo sports 150mm of travel, which should allow for precision and control when descending. A relatively lower bottom bracket, steeper seat tube and slacker head tube angles, and a roomy cockpit should make this an agile and responsive riding experience.

Specialized Stumpjumper Evo
2021 Specialized S-Works Stumpjumper Evo Photo: Specialized

Specialized’s “S-Sizing” for the Stumpy Evo allows you to choose frame size based on terrain and riding style, and not just straight-up measurements. Specialized says that determining size is easy as each of the sizes from S1 to S6 correlates to a previous size. What this means is if you previously rode a medium, then S-3 will be your equivalent size. But, if you want a quicker, more nimble ride, you’d drop down by a size, so in this case to an S2; if you’re wanting for more stability go up a size, so for this example, to an S4.

Specialized’s adjustable head tube angle — between 63 and 65.5 degrees — is facilitated by eccentric headset cups with three settings which can be done trailside. Likewise, the bottom bracket height can be adjusted by a much as 7mm with a Horst flip-chip.

The Specialized S-Works Stumpjumper Evo tunable suspension
The Specialized S-Works Stumpjumper Evo tunable suspension. Photo: Specialized

And, if you’re a fan of mullet bikes — with a larger wheel up front than in back — the Specialized Stumpjumper Evo can do a 27.5-inch rear wheel and a 29-inch front wheel. The travel range is 160mm rear and 150mm front, while the design of the tuned progressive leverage was informed through the development of the Specialized Enduro. Bonus: bobbing and that lost pedaling connection feel is negated through Specialized’s anti-squat design.

The “sidearm” chassis design is evident in the asymmetric strut on the right side of the shock, between the top tube and seat tube. This design should prove to resist twisting frame flex without fattening up the bike’s overall weight. So, not only can you rip down hills with ample responsiveness and control, but climbing should prove out to be easier, too. And Specialized even says with a 2,250g (frame only, size S4) frame. The 2021 Specialized Stumpjumper Evo is available in carbon or aluminum frames, with a wide range of build options.

2021 Specialized Stumpjumper and Stumpjumper Evo pricing

Specialized Stumpjumper alloy models pricing will start at $2,199, while the top-shelf Stumpjumper S-Works model tops out at $9,499. The S-Works frame-only option will set you back $2,799. Stumpjumper Evo models start at $4,099 and top out at $9,899; the Stumpjumper Evo Alloy 29er frameset only runs $1,700.