The Specialized S-Works Stumpjumper FSR Carbon

There is no other trailbike like the Specialized S-Works Stumpjumper FSR Carbon. No other company has the nerve, the wherewithal, or the energy to commit as much energy or has gone to such great lengths to deliver their vision of the perfect trailbike. ‘Compromise’ or ‘making do’ were not permitted with this project. If a component didn’t exist to get a specific job done, no problem. Specialized just made it. 

The S-Works Stumpjumper FSR Carbon (SW Stumpy for short) uses a dual-diameter head tube matched to a Specialized Future Shock fork that uses a dual-diameter carbon fiber steerer tube (molded in one piece with the fork crown). The Specialized fork’s air spring, cartridge damper and inertia-valve anti-bob hardware are all housed in the right leg (the left leg is empty).

The frame tubes are molded separately, bonded together and reinforced with hand-applied layers of carbon at each junction. This process, while time-consuming, is the lightest way to build complex tubular carbon frames.
The SW Stumpy uses a rocker-link suspension. The magnesium-alloy link moves on full-cartridge bearing pivots and drives a Specialized AFR Brain shock with a remote inertia-valve-equipped compensator chamber. An external clicker on top of the swingarm-mounted reservoir tunes the anti-bob function to rider preference. Specialized retains the Horst-Link rear dropout linkage, and the seatstays are carbon fiber, while the swingarm is welded aluminum.

While we’ve touched on the major features, further inspection reveals even more Specialized touches. The tires, rims, hubs, grips, handlebar, seatpost and saddle are all Specialized. Even the Avid Ultimate SL Mag brakes were modified just for the SW Stumpy

The SW Stumpy is a precision instrument, not a bike you jump on and ride off into the sunset. We found that ‘getting close’ doesn’t cut it for setting the SW Stumpy’s suspension. You have to nail it; all of it (air pressure, inertia-valve adjustment and rebound). You will be disappointed if you don’t take the time to set the suspension properly. If you take the time, you will be amazed—and you only need to do it once. After that, minor changes can be made for particular trail conditions, but the bike will be ready to rock.

The new SW Stumpy owner needs to visit the Specialized website and watch the video on proper suspension setup (found on the ‘more info’ link below the bike’s main page).

Getting up to speed: The SW Stumpy feels crazy light because it positions its minimal weight low. The Specialized Roval wheelset and Captain tires give the SW Stumpy cross-country-race-bike-like acceleration. The Specialized AFR Brain shock is amazing. Go ahead, mash a big gear or get out of the saddle. The rear suspension doesn’t fall into its travel unless the tire hits something in the trail. This bike feels like a hardtail that turns into a dual-suspension bike when you need it.

Cornering: The SW Stumpy’s slack head tube angle, tall-feeling head tube, and the resulting handlebar position make the bike feel like a trailbike up front, but its seat tube angle, bottom bracket height and high-riding rear suspension give it a racer-like sensation in the rear. Like the suspension, the Captain tires will not deliver if not set properly. The wrecking crew felt that five-psi could be the difference between sticking and skidding. These narrow tires fall on the cross-country-racing side of trail riding.

Climbing: When 2×10 drivetrains are unleashed (a ten-cog cassette mated to a two chainring crank), the Specialized probably will offer it as an option. Why?  We seldom needed the granny and found ourselves powering up climbs in the middle chainring. Best results were found in a seated position, moving forward on the saddle as necessary to keep the front wheel in contact with the ground on steep climbs.

In the rough: This is where proper suspension setup is a necessity. Wrecking crewers who came back disappointed with suspension performance were sent back to the workshop for a suspension setup review. Changes as small as ten psi in air spring pressure or a few clicks of rebound adjustment (adjustments that would be undetectable on many suspension components) make a big difference. Once set correctly, the travel feels like a long-travel cross-country race bike. It stays light and responsive, even in the rough stuff.

Downhilling and braking: The seven-inch rear brake rotor looks way too big, as does the eight-inch front rotor. These massive discs only come on the large and X-large SW Stumpys and neither felt like overkill in the real world. The front rotor would occasionally scrap a brake pad during climbing and make a very annoying noise. Trying to isolate the reason for this proved fruitless. Checking the quick-release tension as well as all the mountain hardware gave us no clues. We replaced the rotor with a smaller seven-inch rotor and cured the problem.

Again, this bike feels like a five-inch-travel trailbike that responds like a short-travel trailbike, and that’s not a dig. Think precision riding. Use the bike’s great handling and unique suspension to slice and dice the downhills, not plow through them.

One final note; the SW Stumpy rider never has to reach for a lever during a ride. If the suspension was set properly, the suspension’s Brain adapts to the situation at hand. That means it is firm during sprinting and climbing and absorbent when downhilling and hitting the rough stuff.

The SW Stumpy is very much like a Ferrari. If you want a car to commute to work and take the kids to the movies in, a Ferrari is not it. If you want a five-inch trailbike that you can ride hard, put away wet, and neglect, the SW Stumpy is not it either. Both a Ferrari and this bike require a commitment from its driver (rider). And just like the Ferrari owner, a sizable financial commitment is required to enjoy the technology Specialized delivers here.

The rider willing to take the time to set up and understand the suspension and who wants a lot of cross-country racer blood in his trailbike will love the Stumpjumper S-Works Carbon.

Price   $7700
Country of origin   Taiwan
Weight   25 pounds
Hotline   (408) 779-6229
Frame tested   19″ (Large)
Bottom bracket height   13.2″
Chainstay length   16.5″
Top tube length   24.5″
Head tube angle   68.5°
Seat tube angle   74.5°
Standover height   29″
Wheelbase   45.5″
Suspension travel   (front) 4.7″
Suspension travel   (rear) 4.7″
Frame material   Carbon fiber
Fork   Specialized Future Shock S120
Shock   Specialized AFR Brain
Rims   Roval Controle SL
Tires   The Captain (2.0″)
Hub   Roval Controle SL XC
Brakes   Avid Ultimate SL Mag (modified)
Brake levers    Avid Ultimate SL Mag (modified)
Crankset   Shimano XTR
Shifters   SRAM X.O trigger
Front derailleur   Shimano XTR
Rear derailleur   SRAM X.O
Chainrings   Shimano XTR (44/32/22)
Cassette   Shimano XTR (11-34)
Pedals   None (weighed with Shimano XTR)