Twelve months ago, we gave our “Mountain Bike of the Year” award to the Specialized Stumpjumper EVO, but until today it was only available with a carbon frame. A new aluminum version has now been added into the mix, one that takes nearly all of the features of the carbon model, including the SWAT box, and puts them into a more affordable package.
First appearing on the 2016 Stumpjumper, Specialized opened the door and utilized the void space of a carbon downtube with the SWAT box. If you’ve been out of the loop, SWAT is Specialized’s acronym for onboard utilities; storage, water, air, tools, which can be onboard the bike or your person. The Stumpjumper EVO Alloy is the first aluminum frame in Specialized's lineup to receive downtube storage, although I'd bet we'll see it show up on more metal bikes in the future.
Specialized Stumpjumper EVO Alloy Details
• Wheelsize: 29" (MX with 27.5" link)
• Travel: 150 mm
• Alloy frame with SWAT box
• 63° - 65.5° head angle
• Chainstay length: 438 - 443 mm (S1 - S4), 448 - 453 mm (S5, S6)
• Sizes: S1 - S6
• Weight: 15.4 kg / 34.0 lb (S4 w/tubes)
• Price range: $3,800, $5,600 USD. Frame only: $1,900 USD.
SWAT box aside, the Stumpjumper EVO Alloy has 150mm of rear travel and is available with two 29" wheels or a mixed wheel setup.Frame Details
Unlike some other aluminum takes on carbon models, the Stumpjumper EVO Alloy's silhouette is virtually identical to its carbon framed sibling. The half paint/half brushed finish is a clever pat on the back to the 2018 model that boasted some wild geometry at the time, but this new model is further refined and more adaptable.
The aluminum frame also has the same sleek cable routing and adjustable geometry as its carbon counterpart. With the use of neutral or angled headset cups and a flip chip at the dropout pivot, Specialized’s Stumpjumper EVO Geometry Finder
can guide you through all the numbers to choose from. To remove the guesswork, simply enter your riding style and local terrain.
The SWAT box makes its first appearance on an aluminum Specialized frame.
The two hoses running to the rear wheel feed into the front of the top tube and take a turn down the side arm brace, held in place by a plastic shroud.
Adaptability is the Stumpjumper’s speciality where the bike can transform from a bar-dragging corner destroyer to a contemporary trail seeker. A specific MulletLink is available as an aftermarket suspension component purchase to retain the geometry for riders wishing to use a 27.5” rear wheel over the stock 29er setup.Geometry
Size wize, the Stumpjumper EVO family covers a huge range of rider heights, from 150 cm up to 203 through six frame sizes. Specialized uses their “S” sizing scheme which allows riders to choose a couple frame size options to suit their riding styles, ruled by wheelbase not seat tube length. Starting at 385 mm for the S1 and S2, that tube length grows in 20 mm increments and the reach ranges from 408-millimeters to a whopping 528, so all riders should be able to find their happy place.
To match the change in front centers, the 438 mm chainstays on the S1-S4 bikes stretch 10 mm for the two largest sizes. The dropout pivot chip can be flipped to gain an extra 5 mm of rear center and dropping the BB height by 7 mm, which will also slacken the head angle by 0.5º.
Up at the head tube, a 1.0º offset bearing cup can be installed to make the head angle as steep as 65.5º or down to an aggressive 63º, depending on the chainstay setting. The swap is as simple as rebuilding the headset and doesn’t require anything more than a few allen keys.Build Kits
Keeping it straightforward with just two component packages to choose from, Specialized has mixed things up from the options available on the carbon frames. Starting at $3,800 USD is the Comp package with a Fox 36 Rhythm fork and Float X Performance shock, X-Fusion Manic dropper post, SRAM NX drivetrain and Code R brakes, as well as Specialized tires, wheels and finishing components.
On deck for our First Ride is the ‘no compromise’, Elite level build, which lands at $5,600 USD. You’ll find a fancy Fox Factory 36 and Float X suspension, SRAM GX Eagle 12-speed drivetrain and Code RS brakes with dual 200 mm rotors, plus an MRP AMg chainguide with a skid plate. The shoes and socks are Roval Traverse alloy wheels and Specialized’s Butcher T9 and Eliminator T7 Grid Trail.
For those picky riders who like to choose their own parts, the frame kit is available with a Fox Float X Performance shock for $1,900. Ride Impressions
As you might expect, the alloy version of the Stumpjumper EVO rides a lot like the carbon iteration. Despite the large section of the downtube that has been removed, there were no worries about unwanted flex in the front triangle. Housing management carries over from the Turbo Levo aluminum frame with a plastic shroud to capture the lines against the inside of the sidearm front triangle support.
I found the Stumpjumper EVO Alloy to be a very comfortable bike to ride, especially with flat pedals. The soft and linear nature of the rear suspension kept the wheel tracking well while pedalling over small bumps, but that did give way on some large square-edge hits and harsh landings. Adding a 0.6-cubic inch volume spacer helped to ramp up the progression and take the sting out those impacts.
The bike really shines on twisty single track with the feeling of being close to the ground; think slalom meets trail, especially in the low and long setting. The increased leverage requires a bit more PSI in the rear shock and careful navigation through chunky terrain as the bottom bracket hovers just off the dirt. Falling back on the Geo Finder to check some numbers, Specialized suggests the high and short setting for the terrain on my local North Shore trails and I reverted to that setting for more clearance and quicker turning.
Under the downtube, it was refreshing to see an MRP AMg guide with a skid plate. I don’t understand why all bikes aren’t spec’d with this equipment, especially with the lack of chains in supply these days. They’re so light and save you from blowing up a chain or bending a ring, so why not have that extra security?
One part that didn’t fare so well was the Roval rear hub with 18-tooth DT Swiss Star Ratchet internals, which stripped out under normal use - not the ideal way to start the first ride. I can't speculate on what may have caused this. The axle was torqued sufficiently and there were no hard wind-ups on the cranks. All the parts were greased, but not over packed so the teeth didn't engage and the springs were in the correct orientation.
Back in action with some new parts, riding the Stumpjumper EVO Alloy showcased how much fun a shorter travel bike can be on the same old trails versus a big enduro rig. I looked to add in some creative side hits and loved taking the long way around some sections of trail. Adaptability geometry allows riders to transform the bike from an ultra-aggressive, MX-wheeled berm smasher to a platform ready for backcountry missions with more ground clearance and dual 29" wheels to roll fast. These characteristics are some of the reasons why the welded version of the Stumpjumper EVO remains as desirable as its fibrous counterpart.
Look for head-to-head comparisons as the SJ EVO alloy goes up against a handful of other aggressive trail bikes in our Fall Field Test.