Specialized S-Works Stumpjumper 15 first-ride review
What better way to celebrate 50 years in the business than giving one of the most famous trail bikes in the industry an overhaul? Say hello to the new Stumpjumper.
Now in its 15th iteration, Specialized’s Stumpjumper welcomes fresh technology within a trail package that’s designed to do a little more than just ‘trail’ riding. We popped over to the brand’s Dorking HQ to get some time on the mega-blingy S-Works Stumpjumper 15.
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With the updates to the Epic 8 and the Epic 8 Evo, Specialized’s current range kind of trips over itself. The Epic 8 Evo treads well within trail territory where the outgoing Stumpjumper makes its home, and then the Enduro encroaches on the Stumpjumper Evo's turf. To solve this, the brand has ditched the Stumpjumper Evo and fitted its trail mountain bike with 145mm of suspension at the rear, and 150mm at the front.
However, the brand stresses that the new Stumpjumper is capable of more than what’s expected of a trail bike and will be raced by Charles Murray throughout the rest of the EDR season.
2024 specialized stumpjumper 15shock.jpg, by Liam Mercer
The big story behind the Stumpjumper 15 is a new technology called Genie. With Brain and other cool bits and bobs, Specialized is no stranger to proprietary tech and Genie is no different. However, this new shock design aims to blend the traction and forgiveness of a bigger travel bike, while staving off harsh bottom outs and retaining the character of a 145mm trail bike. And despite coming with less travel than the current Enduro, the new bike ‘equals the amount and quality of the travel used’.
So, Genie is a rather clever system built into the Stumpjumper 15’s shock and its air spring and employs what is called a ‘Genie Band’. To put things simply, the Genie shock as a whole utilises two positive air chambers with an inner and outer chamber that combine to provide a large air volume for a more linear feel, more grip and better bump-force management. Then as the shock reaches the 70 per cent mark of its stroke, the Genie Band blocks the outer chamber’s ports, stopping airflow to that chamber which then ramps up progression in the last 30 per cent of the stroke to fend off bottom outs and retain stability.
Of course, there are a load of percentages that come with this as Genie promises 39 per cent fewer severe bottom outs, 57 per cent better traction, and 16.3 per cent better bump force management, which means that the shock will use more travel for the same impact, compared to a regular shock. Interesting stuff.
2024 specialized stumpjumper 15 tt logo.jpg, by Liam Mercer
Running on Specialized’s Fact 11M frame, the Stumpjumper 15 borrows a lot of what we saw on the Evo, including its adjustability. With that, this bike allows the user to shift its head angle through three settings and the bottom bracket height by 7mm. The bike can also be kitted with mullet or 29-inch wheels all without adjusting the angle of the seatpost.
To put the geometry into numbers, an S4 frame (equivalent to a large) gets a 475mm reach, a 64.5-degree head tube in its standard setting, a 76.9-degree seat tube and a 435mm chainstay. The bottom bracket in its high position sits at 337mm. Another important figure is that the standover height is lower at 745mm, which provides a better opportunity for sizing up than before.
Going back to the head angle quickly, the adjustability provided by the eccentric upper headset cup offers a slack 63-degree angle or a steeper 65.5-degrees.
There are six sizes on offer with the S1 and S2 rocking mullet wheels as standard and the rest on 29-inch hoops.
There’s also a refined Swat box or downtube storage. It’s now flush-mounted and has received improvements to its sealing integration and operation.
Specialized S-Works Stumpjumper 15 - Componentry
The S-Works build is the money-no-object build where the brand throws top-shelf componentry at the bike. That kit comes in the form of Fox’s Factory 36 fork and of course that Genie-equipped Factory-level shock.
2024 specialized stumpjumper 15 fork.jpg, by Liam Mercer
Everything on this bike is either carbon or electronic. That means we’ve got SRAM’s XX Transmission drivetrain and a RockShox Reverb AXS dropper. SRAM is a running theme, too, having outfitted the bike with its Maven Ultimate brakes – a nod to this bike’s intentions.
The S-Works bike rocks Roval’s latest carbon wheels wrapped with a Specialized Butcher at the front and an Eliminator at the rear.
2024 specialized stumpjumper 15 mech.jpg, by Liam Mercer
This S-Works build will set you back £10,000. Prices drop to a somewhat friendlier £6,000 and there's an Ohlins-equipped build without Genie for £7,000. The S-Works frameset is priced at £4,000.
Specialized S-Works Stumpjumper 15 - Ride impressions
During my time at Specialized’s UK headquarters, I sampled the new Chisel FS and the top-of-the-range S-Works Stumpjumper 15. Although its frame shape might not be as immediately eye-catching as the asymmetric design of the previous iteration, it’s clear that the brand has still gone all out with a proper cool design with raised ‘wet-look’ texturing throughout. But I must say, as good as it looks I can’t predict how the textured finish will play with a protective frame wrap.
Frame protection aside, it’s a sleek-looking machine that’s understated rather than ‘look at me!’ and that’s an aesthetic I can absolutely get behind.
2024 specialized stumpjumper 15 ht.jpg, by Liam Mercer
As with any bike, the first thing I check is geometry – and when sitting on the 15th iteration of perhaps the most famous mountain bike on the market, it feels rather unremarkable but not in a negative sense. As soon as I perched myself atop its fancy 3D-printed saddle, I felt right at home and within just a few pedal strokes, I was more than comfortable enough to push the bike.
Where the new Stumpy has borrowed geo figures from the previous-generation full-aggro Stumpjumper Evo, there’s a sense of balance throughout the frame. The seat tube angle is right on the money for plenty of climbing, where it doesn’t plant the rider directly over the BB but it’s not cross-country slack either. Weight is well distributed and the riding position is comfortable.
2024 specialized stumpjumper 15 st logo.jpg, by Liam Mercer
The 475mm reach of the S4 frame I rode is by no means long and may be considered reserved for a trail bike but as always, a mountain bike is a sum of its parts and, for the Stumpjumper 15, that rings very true. That’s because when a bit of speed gets under those fancy Roval hoops, that theme of balance continues thanks to the Genie shock that does a fair bit of work here. However, where its wheelbase is comparatively reserved to a similar-sized Canyon Spectral, for instance, the Stumpjumper 15 welcomes rapid cornering aided further by the rear end’s hell-for-leather approach when it comes to grip.
Behind the shock tech, Specialized goes on about how it’s designed to do all this stuff, like use more of its travel and fend off harsh bottom outs but the brand has hit the nail on the head. At speed, the rear suspension is very active when the rear wheel hooks up, absorbing loads of impacts while transmitting none of the harshness to the feet. It remains communicative though and Specialized’s designers have done a stellar job of maintaining some support in the mid-stroke. This keeps the rear end from overusing travel and avoids that vague feeling that comes as a result of lesser support.
This is where a chunk of stability is rustled up as at speed, the rear suspension keeps the bike calm and composed. While riding completely new tracks, I was more than happy to commit to the short technical passages while feathering those mighty SRAM Maven brakes lightly thanks to the confidence the rear end provided.
2024 specialized stumpjumper 15 brake leve.jpg, by Liam Mercer
The new Stumpy does pose something a little different in its ride character, however, because where Spesh says that the Genie Sleeve blocks off the outer portion of the air spring in its final 30 per cent of travel, it really does. When that clever tech engages, progression in the shock ramps up very sharply which makes sense, and works to stave off the clang of a bottom-out. But because that ramp-up is so sudden, that last few millimetres of squish feel like a different system altogether and, to a point, reserved to do only that. It’s not a bad thing by any means, it’s just peculiar compared to conventional shocks that provide a leverage curve that’s not quite as extreme at bottom out. It works, and it’s a trait that many will love but I would like to spend more time with it to understand a little better.
However, I will admit during my couple of hours on the bike, it feels as if it’s as close as we’ve gotten to a ‘have your cake and eat it’ platform where it’s comfortable and mega grippy because the suspension’s so active that you don’t need to worry about smashing the shock’s bump-stop to smithereens. This can all be tuned using volume spacers and the like, too.
But where the Stumpjumper 15’s rear end encompasses everything anyone’s ever wanted from a mountain bike, it’s super calm under pedalling loads. It’s got that spark of a cross-country bike in that when climbing, it’s encouraged me to work a little harder to reap extra speed which has come fairly easily.
With the 15th iteration of the Stumpjumper and the brand celebrating its 50th year, it’s great to see Specialized back innovating. The Stumpjumper remains one of, if not, the benchmark trail mountain bikes. It ushers in interesting technology that heightens the experience. It’s an exciting bike.
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