The Specialized Stumpjumper has been through many changes since it was first introduced in 1981, and for 2019 it underwent another complete redesign as the Californian company attempts to keep pace with rapidly changing mountain bike trends.



Instead of pinning everything on a single model though, there’s now a choice of three bikes: Stumpjumper Short Travel (ST), which replaces the Camber, a regular long travel Stumpjumper, and the Stumpjumper Evo makes a return after being retired four years ago.

Specialized Stumpjumper Details



• Intended use: trail / all-mountain

• Wheel size: 27.5" / 29"

• Rear wheel travel: 150/140mm (27.5", 29")

• 65.5º / 66.5º head angle

• Aluminum and carbon frame options

• Boost hub spacing

• Size: S-XL - Men's, XS-L - Women's

• Price: $1850 - $9500 USD

• www.specialized.com/stumpjumper • Intended use: trail / all-mountain• Wheel size: 27.5" / 29"• Rear wheel travel: 150/140mm (27.5", 29")• 65.5º / 66.5º head angle• Aluminum and carbon frame options• Boost hub spacing• Size: S-XL - Men's, XS-L - Women's• Price: $1850 - $9500 USD

The top-of-the-line Specialized S-Works Stumpjumper.

It was only a matter of time before the asymmetric frame design found on the Demo made it to a trail bike. A flip chip in the yoke allows the head angle to be altered by half a degree, and the BB height to raise or lower 6mm.

Frame Details

The raised portions of the chainstay protector are said to minimize chainslap more than a traditional protector. The SWAT box now has 20% more volume than before.

Suspension

Stumpjumper S-Works: $9500 USD. Stumpjumper Expert: $5500 USD.

Stumpjumper Comp Carbon: $4200 USD. Stumpjumper Comp Alloy: $3000 USD.

Frame Options / Build Kits

Geometry

The Stumpjumper EVO is back, with DH-oriented geometry numbers, including a 63.5-degree head angle.

Five Questions With Jason McDonald, Specialized Mountain Bike Design Engineer

The Stumpjumper ST combines a 130mm fork with 120mm rear travel on 29” wheels while the 27.5” version has 130mm front and rear. The standard Stumpjumper has 150mm front and 140mm rear travel with 29” wheels, and 150mm at both ends with 27.5” wheels. The Evo has the same travel as the standard Stumpjumper but the key difference is in the geometry.Each bike also has clearance for 3" tires, with 2.6" tires specced on the Stumpjumper and Stumpjumper Evo, and 2.3" tires on the Stumpjumper ST. Yes, that's right, there are no separate plus bikes in the range anymore.The Stumpjumper is probably a bike you’re very familiar with. Many people will have either owned, ridden or come close to buying one over the years. Back in 2015, the range split between 29” and the then-new 27.5 Plus wheels, and the unique Swat Box concept was introduced, amongst other changes. But we also saw the retirement of the Evo, due principally to the regular bike having the longer travel and slacker angles that made the Evo model stand out.Well, the Evo is back as a slacker and burlier option than the regular Stumpjumper it is loosely based on, with the same travel but more progressive geometry. At the other end of the range, the Stumpjumper ST replaces the popular Camber with the same frame but different suspension components and is meant to be a more trail capable package than the bike it replaces. And the regular Stumpjumper is the undoubted workhorse of the range.What’s immediately striking about the new bike is the all-new front triangle design. While the shock and linkage orientation are visually similar to the old bike, the top tube now bends around the shock in an asymmetric design first seen on the Demo. It naturally brings to mind Orbea’s Rallon. The key reason put forth by Specialized is to deliver the required frame stiffness, which is increased over the old design, without compromising the position of the shock and the suspension layout. This stems from one of the key development aims: to create a more balanced bike front to rear.Specialized developed a stiffness test to benchmark the frames, and in doing so found the aluminum frame was stiffer and tracked better than the carbon bike. In fact, there was actually a small amount of flex of the carbon frame during compression that was acting as undamped suspension that they wanted to eradicate. The new frame design us said to have a 19% stiffness increase compared to the old carbon Stumpjumper, and every size has been tuned with a Rider First size-specific approach, resulting in different tube shapes and carbon layup to optimize stiffness and weight. That has led to improved stiffness-to-weight on the larger sizes and up to 140g savings on the smaller sizes.The swingarm has also been redesigned, with the reintroduction of the seat stay bridge bringing about a 100g weight reduction and 8% increase in stiffness. With the move from an alloy rear triangle to fully carbon, Comp/Expert frame sheds a sizeable 550g off of the previous edition. And it's out with press-fit and in with externally threaded bottom brackets. Specialized says press-fit offered a weight advantage four years ago, but that the latest bottom bracket and crankset design means it’s possible to develop a lighter bottom bracket shell while also introducing extra reliability. The other big change is the new bike is 1x only, there is no fitting a front mech to this frame.SWAT was first introduced four years ago, and for 2019 this unique cargo feature has been refined even further. It’s now a little lighter, with a sleeker, easier to use interface, and provides 20% extra volume. There’s still space in the front triangle for a water bottle, with the lid of the SWAT acting as a bottle cage holder. A hidden feature Specialized was very proud of is the internal routing for the rear brake hose, and the result of considerable development time. A channel is integrated into the down tube and routes the hose cleanly through the bottom bracket and main pivot into the chainstay, which saves a ton of time and frustration when building bikes. You can literally just push the hose in at the head tube and it pops out next to the brake caliper. Easy.Making the bike quieter has been a focus too. A shaker machine and high-speed camera were used to determine what the chain was doing when you’re bumping and grinding down a steep descent. It found a lot of the noise was created by the chain making a wave and impacting the chainstay in the same places, so Specialized developed a rubber chainstay protector with raised knobs that are aligned to these waves to dampen the noise. The bikes really are very quiet, a fact that's especially noticeable when everyone around you is on the same bike.The Stumpjumper ST and Stumpjumper share the same frame and swingarm, though the 29” and 27.5” frames are slightly different, while the rear triangle is the same. Specialized says it looked to use the same frame for both wheel sizes, but felt it was too much of a compromise. These two models are available in carbon and aluminum, but the new Evo is only available in aluminum, allowing Specialized to test the water with this bike before committing to a carbon version.At first glance, the FSR suspension looks pretty much the same as the previous bike, but there have been some considerable changes aimed at providing improved suspension performance. Autosag is gone, due to the limitations it imposed on the negative spring and transfer port location, and Specialized found it could get the suspension performance it desired with the latest Fox EVOL and RockShox Debonair shocks, with easier tuning setup. To aid sag setup, all bikes will be supplied with a small sagometer.The leverage curve has been made more progressive. This helps provide a more supple action at the beginning of the stroke, more support in the midstroke, and increased bottom out resistance, a change which moves it close to how a coil shock performs according to Specialized. And due to the revised leverage curve, every bike has a shock with a lighter tune than before, with less reliance on volume spacers for more aggressive riders due to the extra support in the midstroke.The linkage is all-new as well, the result of multiple prototype testing. It’s fully compatible with standard stroke and eye-to-eye metric shocks, and in a move that will win it many fans, there’s space for a coil shock. Standard eyelets are used for easy shock swapping and a flip-chip provides a 0.5-degree head angle and 6mm bottom bracket adjustment.There are a wide range of builds to choose from, with aluminum and carbon choices. The Stumpjumper ST gets 2.35” tires, the standard Stumpjumper and Stumpjumper Evo get 2.6” tires, although there's plenty of room to go even wider.Specialized has developed a new version of its Command Post dropper with 160mm of travel, which is used on the larger frame sizes, with a larger air volume to make dropping the saddle easier and a smoother return, along with increased bushing overlap for improved durability and 16 positions of height adjustment.Prices range from all the way up to $1,850 up to $9,500 for the S-Works bike. And all bikes are 1x only.Geometry is the hot topic in mountain bike design right now, and the Stumpjumper has, as you’d expect, gotten longer and slacker. Shorter stems have also been specified across the range, and short seat tubes to allow for longer dropper posts.You won’t find Geometron worrying lengths here, but the numbers are where you’d expect a modern trail bike to be. The geometry is slightly different between the two wheel sizes, but the standard Stumpjumper with 27.5” wheels in a size large has a 455mm reach, 65.5-degree head angle and 432mm chainstays.While the standard and short travel bikes are perhaps more modest in the numbers, the reintroduction of the Evo has allowed Specialized to push the boat out, with the longest of the two 27.5” sizes offered measuring 490mm reach, 63.5-degree head angle and 440mm chainstays.

What was the key design aim with the Stumpjumper?

The key thing we were trying to achieve with this new bike is really getting a bike that’s very well balanced and tracks in all conditions down the trail. So really working on connecting a rider's hands and feet and making sure that the message that your bike is sending from the ground up through the wheels, into the bike, suspension, and into the frame, matches between your hands and feet. If you get a different message between your hands and feet then your body gets confused, it feels unstable and bad things happen. So we really wanted to work on that connection.

So the sidearm is all about increasing the frame stiffness first and foremost?

Yeah, I would say increasing the stiffness to a point. Stiffer isn’t always better, and so with this we did develop a new stiffness test and we were able to really focus on that connection between the rider's hands and feet and figure out where the sweet-spot really was. We benchmarked about ten different frames and various sizes of those frames, some of our own and some of our competitors, and we went and rode all of them and said “Okay what do we like, what don’t we like about these different frames” and characterized them. We also did that with respect to suspension performance as well, but with regard to stiffness and the way the bikes handled, we found that as long as we got to a certain plateau basically, going stiffer than that just meant the bike was overbuilt. And we didn’t need to go there. So we were able to optimize it and get the best ride quality, which in my opinion ride quality also includes weight. Because if your weight is too high, then it detracts from your ride quality. So if you can have the best handling bike, but it’s also one of the lightest bikes, then you’re going to have one of the best all-round bikes. Which is what we were going for.

Was the sidearm the only way of achieving your stiffness goals? Did you look at other design solutions like a twin tube approach?

One of the early carbon prototypes for the new frame design.

We could have, but I don’t think you can achieve the same frame efficiency meaning that the shape of the frame isn’t as optimized otherwise. So with this layout it gives us a much more optimized frame shape that we’re able to make get the stiffness we want at a lower weight basically. I actually think if you put another tube on the other side and made it symmetrical I think it would just end up being heavier, because you have a minimum wall thickness that you want to have for impact resistance. And so you could go under that and make it lighter, but then you’d have a brittle frame that could break. And you don’t want that. So if you add that additional tube you’re just adding weight, and so yes you could make it stiffer but it really doesn’t help you.At the end of the day, with all of this, we look at tube shaping and tube sizes, and we do go in and optimize tube shapes based on the particular stiffness and strength we need out of a tube. And so what that allows us to do is get us the lightest possible setup that is not brittle, not overly built and dead feeling, whereas if you just designed the shape and threw a layup at it, you could be overbuilt meaning when you hit your minimum wall thickness, it’s way too stiff, stiffer than you need it to be, or it could be way too thin as well. That’s why the shape really comes into play with making sure everything’s optimized.And also keep in mind the rider first approach. Everything I’m talking about, we apply to every single frame size with very particular targets for each size to make sure everything tracks perfectly. Much like with the Epic and the [Stumpjumper] hardtail, it’s the same philosophy but different application of that in this sense. This stiffness test I keep talking about, it’s very trail orientated because it only focuses on a rider's hands and feet, whereas the Epic, for example, pedaling is a huge part of it, but that’s not something we focused on here with the new Stumpjumper.

This stiffness test takes into account the differences of a light rider on a small bike and a heavier rider on a large bike and results in different carbon fiber layup?

Yes, the layup of the carbon, and if you look at it the shape of the tubes are scaled accordingly. If you look at the top tube in particular or a large or XL frame, you can tell it’s a little taller and rounder to make it stiffer, the sidearm is also beefed up, taller and thicker on the larger sizes. So it’s really a matter of optimizing the shape of it, that’s what really matters, it’s not just going and putting in some awesome carbon layup, that’s part of it, but you have to have a good foundation to lay the carbon up in. The bottom bracket being 100g lighter than the old one is a great example of how optimized shape can save you a ton of weight.

As well as the new front triangle, there’s an all-new linkage and swingarm. What were you trying to achieve with this part of the new bike?

Making sure everything is well connected. We do see an 8% increase in rear-end stiffness. Comparing carbon to carbon, it’s not only 8% stiffer, it’s also a 100g weight loss in the chainstay and seat stay carbon parts, which is massive, especially given this chainstay only weighs a little over 200g. It’s actually the lightest chainstay we ever made.So compared to the previous Epic or any of those, it’s lighter, except the new Epic with the no Horst link, you can’t really compare that. So super light rear end, being able to have the seat stay bridge in here does help us optimize that as far as the weight goes, and also getting a bridge in the link behind the seat tube really helps. If you figure the whole purpose of the bridge is to connect the two sides of this link, and if you’re really concerned with the link which connects the seat stay to the seat tube pivot, then you might as well connect it in-between those two pivots. So your most efficient use of the material is in that link behind the seat tube versus putting it in front. Historically we haven’t been able to put it behind and so here it’s kind of a necessity because you’ve got the sidearm but you actually end up with a lighter linkage.Specialized boldly pitches the new Stumpjumper as “the ultimate trail bike” so it makes sense to test the new bike on the ultimate trails. But where to go? Ainsa in Spain, host of a round of the Enduro World Series in 2015, proved to be perfect, with some truly fantastic trails and a good mix to put the new bike through a thorough initial shakedown. While a couple of rides is far from enough to really get under the skin of the new bike, it did provide a decent first ride.A little note on Ainsa: it’s an incredible place to ride a bike. If you get a chance to visit, you must. It’s not as well-known as other riding spots across Europe, perhaps, but hidden in the hills and trees are some truly stunning trails, some of the best I’ve ridden in a long while. The region is steeped in history, medieval trails crisscross the hills, snaking up through dense woodland, along river valleys and through abandoned villages. There’s variety on the menu here, everything from steep, tight and buttock-clenching rocky chutes to roller coaster lunar landscapes, with a side-serving of loamy, woodsy singletrack. It’s a real mix and a good place for a trail bike to strut its stuff.It’s a shame the weather wasn’t in our favor, serving up as it did plenty of rain and cold temperatures, but that didn’t stop us getting a couple of good rides in on the new bike. I was able to ride the S-Works Stumpjumper in both 27.5” and 29” wheels in a size large, which provided an interesting comparison between the two wheel sizes when you remove most of the other variables.Both bikes felt right at home on the challenging Ainsa trails. With lots of climbing on the first day, the Stumpjumper’s climbing ability shone through. It’s comfortable and composed, with the suspension providing plenty of support to give the bike a very efficient feeling. We climbed for well over half an hour solid and it didn’t feel like a chore at all. On the smoother trails, I was able to leave to leave the shock in the open mode most of the time, only switching to the middle setting for more support on a rocky, stepped climb that had me wishing I had the trials skills of Danny McAskill. Rocky trail 1: Dave 0.On the descents, the Stumpjumper was a hoot. And definitely very fast. I felt right at home on it immediately ,and that helped me focus on riding and enjoying the awesome trails and not worrying about the bike between my legs. Specialized has hit a nice sweet spot with the geometry, providing that playful characteristic I personally look for in a bike. I was able to easily lift the front wheel and move the bike around the trail, yet there was plenty of that fabled stability for those ‘let it loose’ moments. Add in the sorted equipment, from handlebar width, stem length, suspension components, tire choice, and it’s a bike that works extremely well in all situations I found myself in.It’s probably cliche to say it, but riding both bikes really highlighted the difference between the two wheel sizes. 27.5” had the edge when it came to pure agility and carving tight turns with precision, while the 29” had the extra stability at higher speeds that made mainlining fast rooty gullys a blast. I’d normally lean towards the 29”, but a day spent on the 27.5” had me reassessing that.The Ainsa trails were a highlight, but it was the new Stumpjumper that really impressed. It comfortably tackled long and draggy and steep and techy climbs, fast and loose and tight and technical descents, confirming it has all the capabilities required to be a good all-round trail bike that can handle a wide range of trail types. The trail bike category is heating up at the moment, has Specialized done enough to ensure its Stumpjumper makes it onto your shortlist? First impressions are good, but we'll reserve judgement until we've spent a lot more time on the bike on trails that we're a bit more familiar with.