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Field Test: Specialized Stumpjumper Alloy

The venerable trail bike is as versatile as always, even in its alloy-framed version

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Basics

  • Travel: 140mm front and 130mm rear
  • 29″ wheels
  • 665°/65.5 headtube angle
  • 77.2°/77.8 seat tube angle (size S4)
  • Reach: 475-480mm (S4)
  • Sizes: S1-S6

Pros

  • Versatile, workhorse trail bike
  • Adjustable geometry
  • Good value for an entry-level full suspension bike

Cons

  • Entry-level suspension components feel less at home at higher speeds
  • On the heavy side

Weight

35.6 lb / 16.1 kg

Price

$2,650

Brand

Specialized


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It feels like just last week that we released the Field Test review of the Specialized Stumpjumper Evo Alloy, but it’s already time to write about the Stumpy Evo Alloy’s budget-oriented sibling, the Stumpjumper Alloy. Like its more-aggressive counterpart, the Stumpjumper Alloy rolls on 29-inch wheels and its frame is made, as implied by the model name, of aluminum. Specialized describes the Stumpy Alloy as an “all-access pass for trail adventure,” which is certainly a promising claim. We put it through its paces in Tucson, Arizona, to see how those words hold up when the tires hit the rocks.

This iteration of the Stumpjumper Alloy arrived in 2021 with updated kinematics, more progressive geometry, and a bit less weight than previous versions, aiming to be that do-it-all bike that every brand seemingly wants their 130-140mm bike to be.

Expectations for this Stumpjumper were high from the start. After all, the Stumpjumper web page manages to use nearly all the bike review clichés, with notes about how the bike is “a refined mid-travel ripper that eats big terrain like a gravity-fed beast, handles like a dream everywhere, and climbs like it has a motor” and how the geometry numbers have been tweaked to be more, uh, “carvealicious.” Superlatives aside, the 200mm rotor up front, beefy tires, and tried-and-true Stumpjumper platform seem up to the task of delivering something good.

Moving beyond the neon salmon color (it also comes in a neutral black and a pleasant sage), the frame has a few things to note. First, unlike the carbon version of this bike, the Stumpjumper Alloy uses a Horst Link design rather than flex stays that appear on the latest carbon version. The Horst layout, in line with all the rest of the full-suspension Stumpy’s history, makes for a more relaxed ride than the snappier flex stay design, which was borrowed from the much racier Specialized Epic.

The other frame details look familiar, too: The cables are internally routed, it uses the same asymmetric design as the rest of the Stumpy lineup, and there’s a flip chip on the chainstay that can raise or lower the bottom bracket by 7 millimeters while changing the head angle by half a degree. Sadly, though, this Stumpjumper has no SWAT Box, so we had to go back to using our pockets and hip packs like we did in the old days.

The Stumpy Alloy weighs 35.6 lbs/16.1 kg, making it the heaviest of the full-suspension bikes on test, though to its credit, it arrived with a proper Specialized Butcher and Purgatory tire combo. The bike also came outfitted with a SRAM SX drivetrain, Tektro Gemini Comp brakes, a RockShox 35 Silver fork, an X-Fusion 02 Pro RL shock, and a TranzX 34.9 mm dropper post with 170mm of travel for the size S4 bike.

It’s also worth mentioning that while the Stumpy doesn’t have size-specific everything, it does have two chainstay lengths. Sizes S1 to S4 have 440 to 444 mm chainstays, depending on the flip chip position, and sizes S5 and S6 get an extra centimeter of length, coming in at 450 to 454 mm.

Climbing

Specialized gave the Stumpjumper Alloy a steep seat tube angle, and that forward pedaling position is quite noticeable when climbing. That’s a good thing—being centered over the bike while climbing and having a comfortable spot to perch while mashing makes a huge difference in my willingness to actually try on climbs, even if it did make the dropper post even more crucial when on the flats or even choppy climbs to get the post just a little bit out of the way. The steep seat angle also means that those of us with long legs can run the seatpost high without finding ourselves way out over the rear wheel when pedaling.

Overall, the Stumpjumper was a fair and comfortable climber. Dialed geometry means that it carries the weight well, and it climbs better than some other, lighter bikes.

On both the climbs and the descents, the suspension became a focal point. I found it difficult to settle on the right amount of air pressure for the shock, as it performed best on the climbs with a bit of extra air, but the trade-off was a loss of sensitivity on the descents. On the flip side, I thought it settled into the suspension too much on the climbs when the air pressure was optimized for descending. A climb switch on the X-Fusion 02 Pro RL shock somewhat mitigates the issue, and I consider that little lever a nonnegotiable on this bike, but I would have appreciated a slightly firmer pedaling platform all around.

We also need to mention the SRAM SX Eagle drivetrain: none of us loved it. The group does get the job done, for the most part, but the shifting lags and doesn’t have the satisfying, crisp feel that defines most of SRAM’s range. It also uses a conventional HG freehub body, rather than the XD driver used by the upper-echelon SRAM groupsets, so someone who wants to upgrade the (heavy) SX cassette to GX or above would also need to swap out the freehub body.

Still, the bike does what it needs to do on the climbs: It holds onto every bit of traction, even on the desert rocks, and it’s a comfortable bike to pedal, even if it does like to wallow a bit sometimes. Don’t we all?

Descending

The Stumpjumper’s personality on the climbs—comfortable and versatile—showed similarly on the descents, where, for the most part, it soaked up the harsh hits and chatter nicely.

Since it is a Stumpjumper, it’s meant to be a well-rounded machine, especially in the alloy version. The bike has been through so many generations over more than 40 years that Specialized has more or less cracked the trail bike code, and this iteration of the Stumpy remains easy to ride.

Its 130mm of travel handles nicely on the descents, and the bike’s obvious stability doesn’t overwhelm its ability to play around. Even with the slightly squatty rear suspension, it rides lightly over the sharp desert rocks and feels capable enough to take anywhere an entry-level trail bike should reasonably go.

Throughout the Field Test, we rode the Stumpjumper on a variety of terrain, and the bike definitely isn’t a specialist—it feels similarly comfortable on rolling cross-country terrain and choppy, rocky trails. The geometry is essentially what we’ve come to expect from a modern trail bike, and it works. Compared to many other 130mm bikes, the 65-65.5-degree headtube angle gives it a pinch of extra stability that pairs nicely with the moderate 440-444mm chainstays on our size S4 test bike: all around, it’s a balanced ride. Carvealicious, you might say.

My gripes about this particular Stumpy come from the spec, though I know I’m nitpicking, since the fact that a bike this capable exists for $2,650 is impressive in itself.

The X-Fusion 02 Pro RL lacks finesse, with just a rudimentary rebound dial and a climb switch, so there aren’t too many settings combinations to play with. Similarly, the RockShox 35 fork does absorb some bumps, but doesn’t have the fine-tuning adjustments found on high-end forks. The suspension worked just fine at low speeds, where it did its job of soaking up rocks and giving the bike a pleasant, forgiving feel, but felt less at-home at higher speeds, where the bike felt chattery, and I would have appreciated more sensitivity from both the fork and the shock.

I was also underwhelmed by the base-level Tektro brakes, which did have enough power but lacked initial bite.

As for the good parts, I got along with the Specialized Butcher and Purgatory tires famously. The grippy T9 rubber on the Butcher up front and firmer T7 of the Purgatory struck a nice balance with traction and resistance. Plus, avoiding flat tires in the desert is a good thing, right?

It was also nice to spend some time getting to know the TranzX dropper post. The simple, cable-actuated dropper uses a 34.9 mm clamp, has a decent lever, and, importantly, just plain works.

Photos by Tom Richards