We’ve returned to the unique Stump with 145mm rear travel across the board and 150-160mm forks on all versions. The geometry and modifications are quite similar to the outgoing EVO, but small details have changed and evolved. The biggest change comes in the form of revised kinematics in tandem with new damper technology to maximize benefit.
• 29″ or mixed wheels (S1 and S2 mixed only)
• Carbon frame
• Frame travel 145 mm, fork 150-160 mm
• Head angle 63-65.5°
• Reach 400-530 mm
• 430-445 mm chain stays
• Seat angle 77°
• Wheel size and frame geometry flip chips
• Actual weight: 31.2 lb / 14.2 kg (S5)
• Price: $6,500-$12,000
• S-Works Frameset: $3,500
• specialized.com
Frame properties
Things here look pretty similar to the last generation EVO, with a molded-in headset that allows for ±1° head angle adjustment, a high/low flip chip to change the bottom bracket height and head tube/seat tube angle, and a rocker joint for aftermarket parts. allowing you to run a different size rear wheel. This last element only applies to bikes of size S3 and larger, as the S1 and S2 options are only for mixed bikes.
The Stumpjumper features SWAT 4.0, Specialized’s most advanced in-frame storage solution to date. First seen on the Epic 8, this latest iteration of the SWAT eschews any redundant frame-mounted hardware and instead the hatch door interacts directly with the frame’s carbon, ensuring a snug fit, longevity and great weather sealing. .
One new detail on the Stumpy that’s sure to raise some issues is the removal of mechanical drivetrain cable routing – this bike is wireless-only. Their development team’s argument is that they believe the highest shifting performance available comes from systems like SRAM Transmission, and that the best is what people deserve on this bike.
The bike uses a 200mm rotor native rear brake mount, which is a little surprising given the fact that almost all Stumpjumper builds are equipped with SRAM Maven brakes – these can offer plenty of power on a smaller 180mm rotor. That said, running them with 200s front and rear never felt excessive on this bike.
Geometry
Like the outgoing Stumpy EVO, the Stumpjumper 15 implements a wide range of geometry settings baked into the frame. The head angle can be varied by 1° in either direction from the base position of 64.5° using a set of easily replaceable cups that come with the frame. A flip chip on the chainstay allows the rider to raise or lower the bottom bracket height by 7mm while changing the head and seat angle by 0.5°. All of this combined allows for a very wide range of adjustments, so for now I’ll stick with the stock numbers for the medium head angle and High flip chip position.
As mentioned above, the new Stumpjumper’s head angle is 64.5° – sag enough for just about anything, while maintaining nimble handling in flatter corners. The effective seat angle for all sizes falls right around 77°, although the actual angle the seat tube throws is less than that figure, landing somewhere around 70°. Reach values ​​range from 400mm to 530mm across 6 sizes, with 25mm jumps between all but the largest size, which varies by 30mm. The stack height is very tall for a Specialized, with the head tube length increasing quite significantly on larger bikes.
Bottom bracket drop is 38mm on all bikes except the S1 which measures 41mm. Chainstay lengths vary across the range, with lengths across all six sizes as follows: 430mm, 432mm, 435mm, 435mm, 445mm, 445mm. Again, this data can be modified by the end user with a variety of possible results as you experiment with combinations.
Suspension design
In many ways this is a familiar story, but the characters involved are slightly evolved to allow for a different outcome. Our main character – shock – is the most significantly changed item in the game here, with some new technology allowing for very linear kinematics.
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We learned a lot from developing the Levo SL in terms of leverage. By moving to a slightly lower starting point and with slightly less progression than our previous bikes, we’ve seen improvements in travel consistency and control throughout the range of travel, regardless of shock type. It also helped reduce shock pressures a bit and make the shock setup process a bit easier. Of course, the SL was developed based on stock shocks without the Genie technology having been invented at the time.
When we got to the Stumpjumper 15, we wanted to bring these features again, regardless of the shock type, so you can see the similarities between the Levo SL and the SJ 15 (we’re a bit more progressive on the SJ 15). This amount of leverage works great with the stock dampers and also really helps emphasize what the Genie brings to the table. We don’t need more progression in the early part of the stroke with the extra volume, and the tunable secondary spring ramp is an extra safeguard for all riders looking for maximum support later in the travel. |
Genie shock
Given the linear nature of the Stumpjumper 15, it may seem necessary to implement a more progressive spring to keep the bike from going down hard and often. However, the team behind the bike went in a different direction and instead came up with a shock that makes the most of this linear amount of leverage. The first key element here is the damper’s massive air volume. This corresponds to the outer air envelope of the beer can, called the Extra Volume (EV) chamber. During the first 70% of travel, the shock’s internal air chamber and EV sleeve act as a single air spring that slowly compresses over the course of the wheel’s travel. At this mark of 70%, the slip case inside the damper encloses the EV chamber and isolates the much smaller internal air chamber. This makes for a much more progressive air chamber that allows the damper to ramp up in the last 30% of travel and prevent you from hitting the bottom of the road.
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Specialized Ride Dynamics – the group responsible for developing the Genie shock – called this sliding bushing technology Pneumatic Spring Assist. The opportunities this technology unlocks go far beyond that shock, as outlined in this patent filed last year.
The Specialized Ride Dynamics team tested a wide range of build options with early versions of the Genie shock to arrive at decisions on factors such as the transition point between high and low air volume and whether or not to mount the shock on the back. platform. In the end, they settled on Float as the basis for this technology because any additional benefit of the extra oil volume in the shock was insignificant compared to the gains from the increased air volume. Fortunately, the Float is also a widely available shock with a huge parts availability, so replacement parts for any necessary service will be easy to find.
While this clever technology allows the Genie shock to optimize performance for the kinematics on the Stumpjumper 15, it’s not like the bike won’t work with other, more typical shocks. I had the opportunity to test the bike back-to-back with the Genie and other stock offerings, and while the custom shock seemed preferable, the stock options performed quite well.
Construction kits
All carbon, all with the same layout, but with lots of part differences to differentiate the different build levels. The S-Works frame differs slightly by using a carbon fiber cradle to save weight, but otherwise the frames are the same across the range. Every wheel, except the Öhlins design, comes with a Genie shock.
Driving impressions
For the past few months, the Stumpjumper has been my primary ride for both daily hot bikes and longer rides. That speaks to how much I’ve liked the bike so far, but it also speaks to the adaptability of the platform. Baked geometry and suspension adjustments can fundamentally change the character of the bike and take it from a feeling sharp trail bike to a downhiller, all within the parameters of stock components. In terms of geometry, I find the stock position to be the best for me and my riding terrain. The 64.5° head tube angle is intuitively controlled on a wide range of trails and still feels confident on very steep terrain. This is aided by sufficient stack height to keep you in a strong upright position with good weight over the bars. My only gripe is with the seat tube angle, which I feel is too relaxed. This is probably due to my fairly tall seat height and slacker actual seat tube angle.
I owned an earlier alloy Stumpjumper EVO for years and fondly remember the many good rides I had on that bike. This one is better, mostly in the shock absorption department. The geometry is pretty similar between the two, but the Stumpjumper 15’s ability to stay balanced even in very rough terrain is really impressive. The bike also generates surprising grip for a 145mm wheel, putting it in strong competition with the longest touring bikes in my garage. While the suspension feels quite active, I never felt vague or vague in pumping scenarios – it just moves more than you might initially expect. For those who want the feel of a smaller bike, it’s as simple as adding extra spacers to the Extra Volume shock chamber and adjusting the air pressure.
Last weekend I went on a ride that could only highlight the comfort, capability and solid Stumpy unicycle. At about 95 miles and 18,000 feet of climbing, it was one of the biggest rides I’ve done in recent memory, and I feel like I picked the perfect bike for the mission. There were no gentle descents on the map, each had its own character and terrain differences. Riding the bike in the stock geometry setup, with 1 delimiter in the shock, it felt like enough of a bike to hit some serious elements while remaining efficient enough not to add extra work during the day. The occasional stat drop isn’t so much to inflate my feeble ego as to illustrate the well-rounded nature of the Stumpjumper – it was comfortable and fun to ride all day. It’s worth noting that I played around with the easy-to-reach switch on a few fire road climbs, but ended up preferring to climb with the damper open.
I have a lot more thoughts on this bike, but I’ll try to save most of them for a full review. Stay tuned as this bike is sure to see many permutations as I play around with setups and modifications.