We love the fast and planted feeling of the new Stumpjumper, but not everyone needs 150mm of travel. And if you're in the market for a trail bike that's more nimble and snappy, the S-Works Stumpjumper ST 27.5 takes thing to a whole new level. Its shorter travel (130mm front/130mm rear), and slightly steeper geometry, bring out the true 'feel' of the trail�making popping off lips and railing berms even more lively. Plus, you get even more responsiveness and stability from the 27.5 wheels.
Our design goal for the new Stumpjumper was simple�build the ultimate trail bike, one that feels telepathic. And it turns out that this feeling all comes down to stiffness. Think of it this way: when the frame's telling your hands one thing and your feet another, your brain gets confused with the imbalance and the bike feels unstable. In order to fix this, we had to get to work on dialing-in the materials, shapes, and the layout.
We started by creating our own mountain-specific stiffness test, and then we looked at the layout with Finite Element Analysis (FEA) to see where we could get the biggest stiffness improvements. This led to a big discovery: The Large and X-Large frames needed more front-end stiffness while the Smalls and Mediums were just fine. We were able to create a frame design that was 20% more efficient. And in the end, this proved to be one of the lightest trail frames on the market, today.
When designing the frame with the stiffness targets being a main goal, we developed a radical new sidearm design. The front-end and rear-end are connected at three points, and the sidearm helps keep all these points super stiff and connected, all while taking about 100 grams out of the rear-end. More explicitly, this minimizes frame flex when the rear suspension is active.
We continued down the suspension path with a custom Rx Trail Tune on both the fork and rear shock. Suspension performance is highly dependent on frame, wheel, and rider size, so we use our Rx Tune to get each bike to land in the middle of the adjustment spectrum, and this gives you the biggest possible range to fine-tune your ride. Another focal point of the tune was matching the suspension characteristics between wheel sizes�we developed a specific Rx Tune for each platform. So, no matter what wheel size you prefer, you'll get perfectly linear suspension.
Steps were also taken to make this bike easy to live with. Threaded bottom brackets make a triumphant return, and we made room for up to a 2.8" tire. You're also free to run whatever aftermarket rear shock you want, since we're using standard metric shocks. We revamped the SWAT� box, too, making it sleeker, lighter, and with more volume. And customization is furthered with a Flip Chip that lets you to dial-in your Stumpy to your riding style. Switch it from High to Low and it drops your bottom bracket 6mm and slackens the head tube by half-a-degree. Little details also jump out to surprise you, like a newly designed ribbed chainstay protector that makes chain slap a thing of the past and nearly silences the drivetrain. Lastly, we seriously couldn't make cable routing any easier on carbon models. Full tubes can be found throughout the carbon frame, so all you have to do is push the cable and it'll come out the other end. No more lazy loop, hidden stashes of magnets, pokey spokes, or pillows to cry in.
The build features only top-of-the-line parts, like a full SRAM XX1 Eagle drivetrain, SRAM Guide RSC disc brakes, FOX Factory front and rear suspension (130/130mm respectively), and the best carbon wheels money can buy, the Roval Traverse SL 27.5s.
•Bottom Bracket: SRAM GXP
•Cassette: SRAM X01 Eagle, 12-speed, 10-50t
•Chain: SRAM XX1 Eagle, 12-speed
•Crankset: SRAM XX1 Eagle, Boost™ 148, 170mm crankarm, 24mm spindle
•Fork: FOX FLOAT 34 Factory, FIT4 damper, 3-position adjustment, Kashima Coating, 15x110mm Kabolt axle, 44mm offset, 130mm of travel
•Frame: FACT 11m, full carbon chassis and rear end, asymmetrical design, 27.5 Trail Geometry, SWAT™ Door integration, threaded BB, fully enclosed internal cable routing, 12x148mm dropouts, sealed cartridge bearing pivots, replaceable derailleur hanger, 130mm of travel
•Front Brake: SRAM Guide RSC, hydraulic disc, organic pads, Guide S4 4-piston caliper, 200mm
•Front Hub: Roval Traverse SL, sealed cartridge bearings, 15mm thru-axle, 110mm spacing, 24h
•Front Tire: Butcher, GRID Casing, GRIPTON® compound, 2Bliss Ready, 27.5 x 2.3"
•Grips: Specialized Sip grip, half-waffle, S/M: regular thickness, L/XL: XL thickness
•Handlebars: Specialized Trail, FACT Carbon, 6-degree upsweep, 8-degree backsweep, 27mm rise, 780mm, 31.8mm
•Inner Tubes: Presta, 40mm valve
•Pedals: Specialized Dirt
•Rear Brake: SRAM Guide RSC, hydraulic disc, organic pads, Guide S4 4-piston caliper, 180mm
•Rear Derailleur: SRAM XX1 Eagle, 12-speed
•Rear Hub: Roval Traverse SL, DT Swiss Star Ratchet, 54t engagement, SRAM XD driver body, 12mm thru-axle, 148mm spacing, 28h
•Rear Shock: FOX FLOAT DPS Factory, Rx Trail Tune, EVOL Air sleeve, Kashima Coat, 3-position adjustment w/ Open Mode Adjustment, 190x45.0mm
•Rear Tire: Purgatory, GRID casing, GRIPTON® compound, 2Bliss Ready, 27.5 x 2.3"
•Rims: Roval Traverse SL 27.5, hookless carbon, 30mm inner width, tubeless ready, hand-built, 24/28h
•Saddle: Body Geometry Phenom Expert, hollow titanium rails, carbon fiber base, 143mm
•Seat Binder: Specialized bolt-type, alloy, 38.6mm
•Seatpost: Command Post IRcc, 16-position micro-height adjustable, two-bolt head, bottom mount cable routing, remote SRL lever, 34.9mm, S: 130mm, M/L/XL: 160mm of travel
•Shift Levers: SRAM XX1 Eagle, trigger, 12-speed
•Spokes: DT Swiss Revolution
•Stem: Syntace MegaForce 2, 6-degree, 31.8mm clamp