{"id":66624,"date":"2024-07-02T18:00:00","date_gmt":"2024-07-02T16:00:00","guid":{"rendered":"http:\/\/ce479296-45b4-4b0e-9280-096529998dfd"},"modified":"2024-07-02T18:28:00","modified_gmt":"2024-07-02T16:28:00","slug":"specialized-stumpjumper-15-is-most-capable-and-versatile-yet-thanks-to-new-fox-genie-shock","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/cyclingplus\/rss_feed\/specialized-stumpjumper-15-is-most-capable-and-versatile-yet-thanks-to-new-fox-genie-shock\/","title":{"rendered":"Specialized Stumpjumper 15 is \u201cmost capable and versatile yet\u201d thanks to new Fox GENIE shock"},"content":{"rendered":"

New Stumpy gets geometry adjustment and an entirely new shock, but the EVO is no more <\/p>

By Robin Weaver\n <\/p>

Published: Tuesday, 02 July 2024 at 16:00 PM<\/p>

\n\n

Specialized claims the new 15th iteration of the full-suspension Stumpjumper is the \u201cone bike to rule all trails\u201d.<\/p>

The updated bike\u2019s silhouette looks familiar, clearly taking design cues from the electrified Levo SL<\/a>, which had a makeover in 2023. Like that bike, the new Stumpjumper does away with the sidearm in the front triangle, but there\u2019s far more at play here.<\/p>

Take a closer look at the in-line shock and you\u2019ll see things are a little different. That\u2019s because Specialized has co-developed a shock with Fox, dubbed the GENIE.<\/p>

Specialized says this shock, along with other changes to the frame, enabled it to create the most versatile, capable Stumpjumper yet. In fact, it has gone as far as ditching the EVO version of the bike<\/a>, which I\u2019m sure we can all agree, is a bold move.<\/p>

Robin Weaver has ridden the new Stumpjumper 15 and you can read his first ride review.<\/p><\/div><\/div>

Five things you need to know about the new Specialized Stumpjumper 15<\/h3>
New GENIE shock uses two positive air-volume chambers, which are both tuneable, enabling you to dial in how the 145mm of rear-wheel travel is delivered<\/li>
The latest Stumpjumper offers three headset cups, enabling you to alter the head angle from 63 to 65.5 degrees<\/li>
A chip in the Horst-pivots enables you to alter the bottom bracket height by 7mm<\/li>
All sizes have taller stack heights<\/li>
Largest S5 and S6 size frames get 445mm chainstays<\/li><\/ul><\/div><\/div>
Specialized Stumpjumper 15 frame and suspension details<\/h2>
A revised SWAT compartment is apparently easier to use and offers better sealing against the elements. – Justin Sullivan \/ Our Media<\/figcaption><\/figure>
Specialized is initially only offering the Stumpjumper 15 with its FACT 11M carbon fibre<\/a>.<\/p>
According to the spec sheet, it\u2019s only the S-Works model that\u2019s treated to a carbon link, though.<\/p>
At the bike\u2019s heart sits the new GENIE shock. This is a big part of what promises to make the new Stumpjumper more capable than its predecessor.<\/p>
GENIE in a bottle<\/h3>
$\"Specialized$
Two positive air chambers are connected to increase overall air volume. – Specialized<\/figcaption><\/figure>
When Specialized set out to design a new Stumpjumper, one of the goals was to create a bike with a longer-travel<\/a> feel, yet one that still feels poppy and lively on the trail.<\/p>
To achieve this, the brand considered the level of progression designed into the frame and created by the rear shock. In a bid to limit compromise along the way, the ride dynamics team at the \u2018Big S\u2019 set about experimenting with rear shocks<\/a>, ultimately creating a mutant design of its own.<\/p>
The end result is the GENIE, which has a two-stage tuneable air spring that\u2019s said to improve traction without sacrificing any of the big-hit control later into the travel.<\/p>
Inside, you\u2019ll find two connected positive air chambers, which increase overall spring volume.<\/p>
The idea was to create a flatter, less progressive spring curve for the first 70 per cent of the Stumpjumper\u2019s travel. This is said to provide a suppler, smoother coil-like shock feel, enabling the bike to find greater traction and provide a more comfortable ride.<\/p>
However, as you close in on the final 30 per cent of the travel, air ports to the outer air chamber (the XL shock sleeve) are closed off (by the \u2018GENIE band\u2019, which is designed to slide over and blank them off).<\/p>
$\"Specialized$
At the heart of the new bike is the new Fox GENIE shock. – Justin Sullivan \/ Our Media<\/figcaption><\/figure>
This reduces the spring volume (you\u2019re now relying on the smaller, inner positive air chamber) and effectively ups the spring rate, creating a smooth, progressive ramp-up as you close in on the final part of the Stumpjumper\u2019s 145mm of travel.<\/p>
Both the positive air chambers are tuneable. The outer sleeve accepts snap-together band spacers, similar to those that fit the Fox Float X2 shock<\/a>, while the second chamber uses eyelet spacers as you\u2019d find inside a Float X shock.<\/p>
Both sets of spacers are unique to the Stumpjumper\/Fox GENIE shock and a full complement will come with each bike.<\/p>
That sounds good, but you\u2019re expecting us to tell you the new GENIE shock is some quirky, proprietary size that\u2019ll be a headache down the line, right?<\/p>
Thankfully, Specialized has kept things as simple as possible, opting for a standard shock size (210x55mm), along with a standard Fox damper to help with ease of maintenance. Alternatively, you can easily replace the shock with an alternative of your choosing.<\/p>
This shock, designed to limit compromise and be the best of both worlds, uses an in-line design and forgoes a piggyback reservoir.<\/p>
In back-to-back testing, although the in-line GENIE shock got hotter than its piggyback equivalent, despite this additional heat build-up, the GENIE didn\u2019t lose out in terms of performance, according to Specialized. This is why the brand chose to use it.<\/p><\/div><\/div>
Compare and contrast<\/h3>
$\"Specialized$
The GENIE began life thanks to Specialized’s Ride Dynamics team, who were looking for a more coil-like suspension feel. – Justin Sullivan \/ Our Media<\/figcaption><\/figure>
Specialized was keen to share some comparative stats with us to highlight why the new GENIE shock is better than the standard equivalent.<\/p>
First up, it claims the GENIE shock provides 16.3 per cent better bump-force management. But what does that mean?<\/p>
According to Specialized, if you smash the rear wheel of the old Stumpjumper EVO<\/a>, equipped with a Fox Float X shock, and the new Stumpjumper 15 with the GENIE shock into the same-size bump with the same amount of force, the Stumpjumper 15 will use more of its travel and behave more like the long-travel Enduro<\/a>.<\/p>
$\"Specialized$
This graph illustrates that during the same level of impact force, the new Stumpjumper will use more travel to absorb the bump, but still offer enough support and ramp-up later in the travel to ensure you’re not blowing through it and bottoming out continuously. – Specialized<\/figcaption><\/figure>
You could achieve a similar result by running a lower pressure in the shock on the older bike, but it couldn\u2019t then match the support or end-stroke ramp-up of the new bike in quite the same way.<\/p>
Next, Specialized says when comparing the new GENIE shock to a standard shock designed to be as progressive, there\u2019s 57 per cent less \u201ctraction loss time\u201d. This is measured using the rotational speeds of the front and rear wheels under braking. That means the overall amount of time the rear wheel slips relative to the front, taken from 82 runs down the hill.<\/p>
Then there\u2019s \u201ctraction loss intensity\u201d, which highlights the differences in wheel speed between the front and rear when a slip occurs. Specialized says the GENIE shock helps reduce traction loss intensity by 27 per cent.<\/p>
$\"Specialized$
Revised Roval Travese SL II rims are reported to provide better comfort and resist pinch flats more effectively. – Justin Sullivan \/ Our Media<\/figcaption><\/figure>
In simple terms, this should mean the supple nature of the GENIE shock enables the rear wheel to move freely enough to keep the tyre in contact with the dirt more consistently through the bumps, preventing it from sliding out.<\/p>
Another metric Specialized was keen to share was based around severe bottom-out events when you use all of the available travel during a big impact. With the GENIE and standard shock set to the same sag level using the same-sized volume spacer, Specialized claims the GENIE suffered 39 per cent fewer severe bottom-out events over 41 laps.<\/p>
It also says there was 11.3 per cent less bottom-out event time, suggesting that when the GENIE does bottom out, it\u2019s not as intense as it might be on a regular shock.<\/p>
Of course, bottoming out a shock is common and not the end of the world, but do it time and time again aggressively and you\u2019ll likely damage the shock, as well as throwing your control of the bike off when these events occur. Tighter control over this, while still having a sensitive initial part of the travel, is the goal here.<\/p>
Other stats include 10.5 per cent less chassis pitching with the GENIE shock and 11 per cent less \u201cuncomfortable vibration exposure\u201d.<\/p><\/div><\/div>
Goodbye EVO and sidearm<\/h3>
$\"Male$
The Stumpy EVO (pictured) has been consigned to the history books. – Russell Burton \/ Our Media<\/figcaption><\/figure>
At present, the Stumpjumper 15 is only available in Specialized\u2019s FACT 11M carbon fibre.<\/p>
There\u2019s also no Stumpjumper EVO available. In short, the EVO has been consigned to the history books, largely down to how capable and versatile the new Stumpjumper 15 is designed to be.<\/p>
Other frame news worth noting is Specialized has ditched the asymmetrical front-triangle design, which included a sidearm bridging between the top tube and seat tube on the driveside of the bike. Losing this freed up more space, buying the engineers valuable real estate to fit a chunkier shock and more space for a bottle, among other things.<\/p>
Specialized says that although the sidearm has gone, the new Stumpjumper 15 is stiffer and just as strong as its predecessor.<\/p>
The engineers have also worked hard to improve the amount of seatpost insertion available, so riders of all heights are able to run the longest-drop post possible. Depending on the frame size, the new Stumpjumper 15 features 50-70mm more post insertion, which is significant.<\/p>
Of course, we can\u2019t overlook the suspension platform. After trying a wide variety of suspension designs (we\u2019re told just about every option was explored), Specialized settled on the tried-and-trusted FSR, four-bar Horst-link design. It opted for this approach because it\u2019s simple, uses an efficient structure and could be tuned to the brand’s requirements.<\/p>
The anti-squat has also been tweaked, leaving it lower than that of the Stumpjumper EVO and higher than the old Stumpjumper, all in a bid to balance suspension performance with efficiency. That means at around the sag point, anti-squat will be just over 100 per cent, dropping off steadily as the bike makes its way through its travel.<\/p>
And, if you\u2019re a fan of wedging kit, tools, clothing or even food inside your frame, the SWAT 4.0 down tube storage is designed to make your life easier. It\u2019s now apparently sleeker, using a short lever to open and lock it, as well as being better sealed against the elements.<\/p><\/div><\/div><\/div><\/div>
Specialized Stumpjumper 15 geometry details<\/h2>
$\"Specialized$
Upping the amount of adjustment on the frame, along with adopting similar geometry to the current Stumpjumper EVO model, means Specialized has killed off the EVO for 2025. – Justin Sullivan \/ Our Media<\/figcaption><\/figure>
While the EVO might now be officially dead, the latest Stumpy inherits a lot of its adjustment \u2013 as well as its angles. So, while the EVO isn\u2019t around anymore, it still sort of is.<\/p>
There are three different-angled headset cups to choose from, each offering one degree of adjustment (the middle setting is 64.5 degrees). Flip chips<\/a> in the Horst pivot enable you to alter bottom-bracket height by 7mm (it\u2019s 337mm in the high position). In the low bottom bracket setting with the slackest headset cup, the head angle is a highly relaxed 63 degrees.<\/p>
The inspiration from the outgoing EVO doesn\u2019t end there, though. While steeper than the current Stumpjumper, the latest bike\u2019s seat tube angle is pretty much identical to that of the EVO, at 77 degrees. This should help promote an efficient seated position from which to attack the climbs.<\/p>
$\"Specialized$
A flip chip at the Horst-link pivot enables you to alter the bottom bracket height by 7mm. – Justin Sullivan \/ Our Media<\/figcaption><\/figure>
Specialized will only offer the S1 and S2 frames with mixed-wheel builds<\/a>. Sizes S3-S6 use 29in wheels at the front and rear, but should you wish to downsize the back wheel, Specialized will have aftermarket links for sale that will enable this without disrupting the geometry.<\/p>
With the two smaller sizes rolling on a smaller rear wheel, chainstay lengths are a little more compact, at 430mm and 432mm. The S3 and S4 sizes (both on 29in wheels front and rear) use a 435mm chainstay, while the S5 and S6 boast longer 445mm stays to better help position the rider between the wheels.<\/p>
Compared to the regular Stumpjumper and the Stumpjumper EVO, the new bike has taller stack heights, with the biggest jump up coming on the larger frame sizes.<\/p>
<\/colgroup>

\ufeff<\/th> S1 <\/th> S2<\/th> S3<\/th> S4<\/th> S5<\/th> S6<\/th><\/tr><\/thead>

Seat tube angle<\/b> (degrees)<\/td> 77<\/td> 76.5<\/td> 77<\/td> 76.9<\/td> 77.3<\/td> 77.6<\/td> <\/tr>
Head tube angle<\/b> (degrees) mid-pos<\/td> 64.5<\/td> 64.5<\/td> 64.5<\/td> 64.5<\/td> 64.5<\/td> 64.5<\/td> <\/tr>
Chainstay<\/b> (mm)<\/td> 430<\/td> 432<\/td> 435<\/td> 435<\/td> 445<\/td> 445<\/td> <\/tr>
Front centre<\/b> (mm)<\/td> 720<\/td> 751<\/td> 780<\/td> 812<\/td> 843<\/td> 879<\/td> <\/tr>
Seat tube<\/b> (mm)<\/td> 385<\/td> 385<\/td> 405<\/td> 425<\/td> 445<\/td> 465<\/td> <\/tr>
Top tube<\/b> (mm)<\/td> 541<\/td> 573<\/td> 595<\/td> 624<\/td> 647<\/td> 677<\/td> <\/tr>
Head tube<\/b> (mm)<\/td> 95<\/td> 100<\/td> 110<\/td> 125<\/td> 140<\/td> 155<\/td> <\/tr>
Fork offset<\/b> (mm)<\/td> 44<\/td> 44<\/td> 44<\/td> 44<\/td> 44<\/td> 44<\/td> <\/tr>
Trail<\/b> (mm)<\/td> 129<\/td> 130<\/td> 130<\/td> 130<\/td> 130<\/td> 130<\/td> <\/tr>
Bottom bracket drop<\/b> (mm)<\/td> 41<\/td> 38<\/td> 38<\/td> 38<\/td> 38<\/td> 38<\/td> <\/tr>
Bottom bracket height<\/b> (mm) – high<\/td> 334<\/td> 337<\/td> 337<\/td> 337<\/td> 337<\/td> 337<\/td> <\/tr>
Wheelbase<\/b> (mm)<\/td> 1149<\/td> 1181<\/td> 1213<\/td> 1244<\/td> 1285<\/td> 1322<\/td> <\/tr>
Standover<\/b> (mm)<\/td> 738<\/td> 751<\/td> 745<\/td> 745<\/td> 745<\/td> 751<\/td> <\/tr>
Stack<\/b> (mm)<\/td> 608<\/td> 618<\/td> 627<\/td> 640<\/td> 654<\/td> 667<\/td> <\/tr>
Reach<\/b> (mm)<\/td> 400<\/td> 425<\/td> 450<\/td> 475<\/td> 500<\/td> 530<\/td> <\/tr>
Fork length<\/b> (mm)<\/td> 551<\/td> 561<\/td> 561<\/td> 561<\/td> 561<\/td> 561<\/td> <\/tr>
Seat post max insertion<\/b> (mm)<\/td> 245<\/td> 245<\/td> 255<\/td> 255<\/td> 285<\/td> 285<\/td> <\/tr>
Seat post min insertion<\/b> (mm)<\/td> 80<\/td> 80<\/td> 80<\/td> 80<\/td> 80<\/td> 80<\/td> <\/tr> <\/tbody> <\/table>