Bike Test: Specialized S-Works Stumpjumper FSR Carbon 29

If you are steadying yourself because you already saw the $9900 price tag, take a deep breath. Specialized offers the Stumpjumper FSR 29 and 26-inch-wheeled versions at various price points. Specialized didn’t build the S-Works to hit a predetermined budget; instead, they built this bike to see how far they could push the boundaries of the modern-day trailbike. Friends, we’ll tell you now, they have pushed the boundaries to a point where others will have to play catch-up.


The Stumpjumper is for the trail rider who likes to be challenged by rocky/rooty trails, steep descents and 4-foot drops and doesn’t want to get left behind on the climbs. The S-Works Stumpjumper FSR Carbon 29 (we’ll call it “S-Works” for the rest of the test) does all these things with one difference—it doesn’t hang in there on the climbs; it makes the others chase. WHAT IS IT MADE FROM? The frame and stays, are all carbon fiber. The frame geometry is optimized for 29-inch wheels. The FSR rear suspension pivots on full-cartridge bearings and is controlled by the Fox/Specialized Brain shock (more on that in a minute). The bottom bracket is a PressFit 30, and the rear-wheel spacing is 142 millimeters. 

The Specialized product managers pulled out all the stops, gracing the S-Works with Specialized-developed components like the carbon fiber cranks and rims, Roval hubs, dropper seatpost, carbon fiber bar, tires (mixed and matched to boost performance), grips, and even a chainstay pad. Little touches—like the bumpers on the ends of the crankarms and the adhesive rub guards on their sides—demonstrate that Specialized knows if you are spending this much money for a mountain bike, you want to keep it looking great.

Specialized’s “Brain” shock technology is a breath of fresh air. The remote compensator chamber near the rear hub houses an inertia valve. This inertia valve (a cylindrical brass weight) senses when the rear wheel is taking a hit from the trail (as opposed to the rider’s pedaling) and opens the shock’s damping circuit. This keeps the suspension firm for pedaling and supple for soaking up bumps. A “Trail Tune” adjustment (they call this “Brain Fade”) allows a rider to dial in the point where the shock becomes fully active. But wait, that’s not all.

Specialized has developed a proprietary “Autosag” feature for their shock. This is the biggest advancement in rear- suspension performance since elastomer bumpers were cast into the dumpster. Don’t understand rear-suspension sag? You don’t have to with Autosag. Pump the shock to any ridiculously high psi setting you want, sit on the bike, push the Autosag valve, and the rear suspension adjusts to the perfect sag setting automatically. Don’t like Specialized telling you what that is? No problem. You can still add or remove air from the shock manually. 

Setup: You got the scoop on the shock. The fork has two travel settings. Begin in the long-travel mode and dial in about an inch of sag. The fork has Fox’s CTD modes (Climb, Trail, Descend) with Trail Tune, which allows you to choose between three firmness options while in the Trail mode. Since CTD is the polar opposite of the Brain in its approach to suspension, we recommend you try to mimic the Brain performance by running the fork in “Trail” mode using the firmest Trail Tune setting.

Ergonomics: This is a big bike. A few of the wrecking crew fall into that gray area where a medium or large frame will fit. Not with this bike. The large-size frame is for large riders or riders under 5 foot 11 with Kermit the Frog-length legs. The rider sits inside the bike, but you still sense a slightly rearward weight bias. The riding position is upright and proved more comfortable the longer the ride. The bar is plenty wide, while the saddle is on the racer-firm side of comfort. 

Moving out: The S-Works has big wheels, meaty tires and a 2×10 drivetrain, so you don’t expect explosive acceleration. Surprise. The S-Works takes every watt of your power and turns it into forward momentum. The carbon rims certainly help. And with the laterally rigid bottom-bracket area and carbon cranks, you can get up to speed fast with less effort.
Cornering: The S-Works inspires confidence immediately. The bottom bracket height feels lower than it measures, and the active suspension works great, allowing the bike to carve corners even when the terrain is chattery. The suspension remains active when needed. The super-light, unsprung weight of the bike helps this and keeps the bike moving through its travel exactly when it’s needed. Small-bump compliance was a shocker. Riders who have not experienced the Brain shock with Trail Tune don’t believe it can tune out all the chatter, but it does. The only caveat is that the bike’s long wheelbase makes tight switchbacks a bit of a balancing act.

In the rough: Our loops are littered with sections that raise the adrenaline level and cannot always be cleaned while riding a 26er. Not so on the S-Works. Whereas riders on smaller-wheeled bikes need to ride aggressively to stay on top of rocks, roots and ruts, the S-Works rider can remain in a comfort zone and still clear sections going either up or down a trail. We had to get used to using a slightly larger gear than normal, because the S-Works allows you to. We had better success torqueing through sections than spinning through them. 

Climbing: Use the same trick as above. Go outside your comfort zone and push a slightly bigger gear. This bike will motor. Drop the fork travel? We never did. Turn the fork to Climb mode? Again, we never did.

Descending: Drop that saddle with a push on the remote lever and let it rip. We caught ourselves picking lines like we were riding a 26er, which is the wrong way to ride this bike. The beauty of these wheels is you can get very creative with mixing rocks, ruts and obstacles into your line. No reason to avoid them. That’s a good thing, because the long wheelbase does not serve well for quick line changes.

These tires will find their way onto other brands; they are that good. We intentionally tried crazy off-camber sections just to see what it would take for the S-Works Purgatory tire to reach its limit. We seldom could get it to slip. It was amazing, and that was with tubes. Tubeless would be even more amazing.

Braking: The Shimano stoppers proved plenty powerful for these big wheels, but they did get noisy when hot. The 7-inch rotor in the rear (the front is an 8-incher) proved to be the worst offender.

We removed the chainguide and noticed a slight increase in chain noise on the descents, but not enough to bug us. Plus, the drivetrain works smoother without it. If you are an aggressive rider (jumping and banging down rocks), leaving it on will add some dropped-chain insurance.

Do yourself a favor; find your favorite Trail-mode setting on the fork and forget messing with Climb or Descend modes. Leave the TALAS (Travel Adjustable Linear Air Spring) in its full-travel setting. This strategy will produce the best suspension balance between front and rear.

Pull the tubes from the tires and convert to tubeless. Since our trails are hardpacked most of the year, we’d be tempted to give up a bit of the bite and durability of the stock tires in favor of a lighter tire like the Specialized Renegade or Fast Trak. Talk about blasting off.

The Specialized Command Post Blacklite dropper seatpost’s remote lever is ergonomically awkward. It requires a twist of the wrist to get the thumb on top of it and a lot of effort to activate it. We have been spoiled by both the KS Lev and RockShox Reverb posts, and if we could afford a $9900 bike, we’d keep the Blacklite for a backup and substitute one of the two mentioned above.

This is the best beginner mountain bike we have ever tested, and we’re not being wise guys. The S-Works handles scary terrain exceptionally well, even if its pilot is a bit tentative. It tracks through or floats above loose, sandy terrain effortlessly. It claws its way through rock gardens like the Mars rover. It hammers along singletrack or rockets up climbs without asking its pilot to make any adjustment to its suspension. In general, it forgives your mistakes. In the hands of an experienced rider, there really is no limit.

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