I owned the last generation Specialized Stumpjumper and have ridden the 2021 Stumpjumper EVO quite a bit and was curious how Specialized could come up with something special for this new 2021 Stumpjumper release. I mean the 2021 EVO is so light, capable, and adjustable already!
What they did was go “all-in” on a lightweight trail bike. They attacked the category with an assault on weight, stiffness, and climbing ability. A sub 5 lb frame with a complete bike just a hair over 26 lbs? And this new Stumpjumper with 130mm of rear and 140mm of front travel is ready to take on descents and corners as well with a fascinating new suspension and a geometry that pushes the envelope.
The new 2021 Stumpjumper comes to market with a singular focus on being the best climbing/descending trail bike available.
2021 Specialized Stumpjumper Highlights
- 130mm Rear, 140mm Front travel
- Features a flex carbon seatstay instead of the Horst Link pivot
- DPS rear shock where the compression and rebound damping vary according to the speed and size of the hit.
- 6 sizes that are riding style specific, not height constrained to a single size
- Sub 27 lb weight in top-spec with a sub 5 lb frame
- Flip-chip with half degree of head angle adjustment and 7mm of bb height
- Five models range in price from $2200 to $9500
It’s good that the Stumpumper EVO exists
The Stumpjumper line used to be a confused array of ST, EVO, Standard and even the Camber bikes that were hard to differentiate from each other. Specialized sought to deliver clarity to the line by just offering two trail bikes, the Stumpjumper and Stumpjumper EVO for rowdier affairs.
The Stumpjumper EVO is the sibling with the wild side, ready to take on owners who don’t know exactly what they want or what adventures this bike will take them to. It has six available geometries and a sweet spot bigger than most oversized tennis rackets. Its existence allowed the Stumpjumper to focus on the pursuit of the ultimate climbing and descending bike.
Because the EVO exists, Specialized engineers were able to make choices and simplify this bike. No 27.5 wheel options, adjustable headset, Fox 36 or 4-piston brakes. This was free to roam the limits of a lightweight trail bike.
Flex Stays instead of the tried and true Horst Link
A monumental choice is the use of flex seat stays instead of the Horst Link to take up the angle change of the rear triangle during suspension compression. This was a risk since employing a flex stay usually involves introducing a spring force into the package. Carbon fiber can flex if designed properly but it’s always going to want to return to neutral with some force, like a spring.
But Specialized was confident in going down this alley since they used the same system in the new Specialized Epic. And they have substantial experience with carbon fiber layering, tuning, and measurement. They’ve also complemented this element with a highly advanced shock tuning in their in-house suspension lab. What they came up with is a design that uses the flex stay as a negative spring for the rear shock. It is then neutral at sag and linear in positive spring force during travel.
The shock was specially designed to complement this frame with a shock with special powers to work with this new Flex Stay. The Fox DPS shock uses a digressive damping option. It is slower during low speed to control that spring during pedaling. And then on high-speed hits, it speeds up to provide a more active feel.
For rebound, the setting is light damping at the beginning of the stroke for a lively feel. But at the end of the stroke where heavier riders push the limits of the shock, the rebound damping slows down. This controls the action on heavy hits and keeps the rider safe and not catapulted back with too fast a return motion.
The shock curve too is very linear with very little progressivity to allow usage of the entire, precious 130mm of rear travel. But at bottom out, the shock ramps up very quickly to avoid a jarring bottoming out of the shock. This kind of tuning optimizes the 130mm of travel for maximum usability.
Why no Enduro suspension, adjustable headset and wheelsize options?
What this bike has is focus on the task at hand and that’s what makes it special. There are other options in the line-up for different folks so this bike was able to pursue the dream of a lightweight bike that can descend with panache.
While some may be disappointed that this doesn’t sport the new Enduro lower link suspension or the EVO’s adjustable geometry. Specialized hopes that the target market will be able to appreciate its simplicity and capability.
The Specialized Enduro is a special bike featured HERE and the new Stumpjumper EVO is chameleon-like beast featured HERE. The presence of both those bikes allowed the Stumpjumper to keep it simple for the trail rider.
How does it ride?
Before we get into the other details of sizing, carbon lay-ups and components, let’s get into the ride qualities of this bike. The bike I rode was the S-Works in S3 size with a 35mm stem. $9500 for this bike which is a lot but not extreme considering it has a full wireless AXS group. Weight came in at 26.3 lbs without bottle cage and hidden topcap tools.
Climbing was lively, It felt like my old Epic EVO with a Brain shock that weighed in at 25.5 lbs. It felt very neutral and stable at the sag point and it wasn’t bouncy at all. Every little bit of pedal input seemed to contribute to the forward motion, both on fire roads and bumpy singletrack. I used flip-chip on the low setting, delivering a head angle of 65 degrees and a seat angle of 77.5 degrees.
The steep seat angle of 77.5 had me perched on top of the pedals of this S3 with a long reach of 450mm. It neutralized the slack head angle on steep climbs and had me motoring with the responsive 432mm chainstays.
Climbing was a little bit foreign to me. Instead of sagging and bobbing under heavy power, it seemed to float. It’s nicely damped to control bob and the suspension had the illusion of springing me forward, making for a lively climb.
Cornering so far has been good. It seems like this bike is so laterally stiff and responsive that it’s easy to position the tires and rail. Hold a line or dance around and weight and unweight the rear tires and it seems very responsive. It’s nicely complemented by these lively tires and the capable new Purgatory and Butcher tread patterns.
Descending is really cool as it is so nimble! This is one poppy trail bike as it really comes alive on little undulations, roots, and rocks. It is so easy to launch! And with its 26+ lb weight, so easy to throw around in the air (if only I knew how to do it better). It’s really a delight to play with even in old, seemingly boring trails.
One of the test jumps we repeated was a rock feature that had a flat landing. Used most of the suspension but never bottomed it out. Landings did feel different from the Stumpy EVO as I felt I was encountering a spring or that heavy ramp at the end of the travel at bottom out. Never pogo’ed me though as the shock seemed to control all the shenanigans.
It’s a lively bike that I can certainly do laps with and have the energy to climb it since it feels so light and efficient. A trail like Soquel Demo Forest with its easy and poppy Flow Trail and burly Braille trail with all its option lines seems perfectly matched for this bike.
Geometry is never an easy discussion as things have changed so much over the last few years and not everybody is ready for the new “progressive” geometry. And rider style and local terrain have a big part in it as riders from the West Coast, East Coast, Morgan Hill, or Germany have different demands. But the flip-chip is still present and that it’s easier to use now with better labeling. It changes the head angle by .5 degree and the bottom bracket height by 7mm.
The Stumpjumper went with a 65-degree head angle and a 77.5 seat angle (S3 size bike on the Low setting). This is spot-on in our opinion since its very progressive but with a flip-chip option and different sizing options to control reach and wheelbase for the same-sized rider.
Chainstay is a very short 432mm with ample tire clearance for S1 to S4. But something cool is S5 and S6 bikes get a 442 mm chainstay to balance out the very long reach measurements. Also, very tall riders use a lot of exposed seatpost and that puts them back over the rear axle.
6 different and unique sizes
There six unique sizes from S1 to S6 with a reach range 415mm reach to 535mm. The options are staggering indeed and with low seat tubes, thus each rider can choose between two or three sizes depending on their style and terrain.
Something notable is each size has its own carbon layup, size, and shape of tubes. They are built to a certain ride quality spec so great lengths are taken to deliver the right characteristics. In fact the S1 (for smaller riders) not only has a reshaped top tube but it also has a lower bb to fit the riders that are likely to use this size.
Another variation to the theme is the S5 and S6 have longer chainstays by 10mm to better center the taller riders that will use these bikes.
The SWAT door on the Stumpjumper EVO is a novel piece of carbon fiber construction and optimization. A simple pull and twist of the water bottle cage open into a deceivingly cavernous downtube storage compartment.
And with many iterations under their belt, the SWAT door is now optimized, maintaining the same frame stiffness while only adding 80 grams of weight to the frame. Storage is large enough to take the contents of a hip pack and all that weight is placed lower in the frame, compared to a pack.
What about alloy?
It looks like much of the engineering has been performed on the carbon frames and matching suspension tuning but what about alloy where flex stays are not possible? In those frames, the Horst Link is used just as in existing Stumpjumpers. The suspension is not tuned any differently so we’ll have to see how they ride and if their personality is much different than the carbon versions.
Weight too will not be as light with the use of alloy for the whole frame and the Horst link pivot with its associated bearings. But it gets the price points to $2199 for the Stumpjumper Alloy and $3199 for the Stumpjumper Comp Alloy.
Color us impressed. At first glance, this 2021 Stumpjumper may not look very different from its predecessor but a deeper look reveals that every part, every layer of carbon fiber was touched. And the first few rides have revealed a bike with enthusiasm for both climbing and descending.
The geometry, shock tune, components sing in harmony to deliver a 5 lb frame and 26+ lb bike in top spec. And the sizing options and storage options deliver something unique to the market with very polished solutions.
The departure from the Horst Link is a bit of the risk as far as descending is concerned since it introduces a spring into the system and we don’t know of another company that has successfully pulled off a no-compromise descender with this system. But the first few test rides have been a delight. And it really seemed to help the climbing abilities of this bike, not just in weight but in liveliness.
For more information, visit: Specialized.com