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Specialized Stumpjumper Comp Alloy review

Forward thinking geometry and great performance at a modest price

Our rating 
4.5 out of 5 star rating 4.5
GBP £2,500.00 RRP | USD $3,500.00 | EUR €2,999.00
Specialized Stumpjumper Alloy Comp trail mountain bike

Our review

A fantastically capable and fun-to-ride trail bike with a surprisingly reasonable price tag
Pros: Excellent on the downhills, thanks to great geometry and suspension; refined, premium-feeling package without the associated price tag; near-silent operation; comfortable saddle and grips
Cons: Fox 34 Rhythm fork holds it back on steeper trails
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The latest iteration of the iconic Specialized Stumpjumper has been given the ‘longer, lower, slacker’ treatment and updated with Specialized’s S-Sizing, where seat tube lengths are kept short so you can choose a frame size based on reach instead. It looks like a brilliant step forward for the brand.

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Specialized Stumpjumper Alloy Comp details

  • No SWAT: Alloy Stumpjumpers don’t have the down tube SWAT (Storage, Water, Air, Tools) compartment of their pricier stablemates, but this bike gives you a similar parts spec to the carbon Stumpy Comp for £1,000 less.
  • Hush-hush: The Specialized is seriously quiet on the descents thanks to its inbuilt chainstay protector and well-thought-out internal cable routing.
  • Hydration station: There’s plenty of space inside the front triangle for a full-size water bottle, thanks to the cage bosses being mounted nice and low on the down tube.

Specialized Stumpjumper Alloy Comp frame, geometry and suspension details

While pricier Stumpys, such as the Expert, get a carbon fibre frame with a tweaked suspension design that relies on seatstay flex instead of a rear pivot, the Comp Alloy is aluminium and uses Spesh’s usual four-bar ‘FSR’ system with Horst-link pivot in front of the rear axle.

It forgoes the carbon bike’s down tube SWAT storage, but has the same geometry, 29in wheels and 130mm of rear travel, plus shares the single-sided ‘Sidearm’ strut that spans the top tube and seat tube shock mounts.

You get Boost axle spacing, a single bottle mount and ribbed chain-slap protection. The brake and gear lines are routed internally, and a 73mm threaded bottom bracket (BB) simplifies maintenance.

The S-sizing means you can pick a bigger frame for a more stable ride or a smaller one for flickability.

Thanks to a Horst-link pivot flip-chip, geometry is adjustable. My S4 test bike had a diminutive 425mm seat tube, paired with a roomy 475mm reach and 615mm effective top tube length (in the ‘low’ setting).

Seat angle (degrees) low/high77.7/78.277.7/78.277.5/77.977.2/77.777/77.576.9/77.3
Head angle (degrees) low/high65/65.565/65.565/65.565/65.565/65.565/65.5
Chainstay (mm) low/high444/440444/440444/440444/440454/450454/450
Seat tube (mm) low/high385/385385/385405/405425/425445/445465/465
Top tube (mm)545563586615643676
Head tube (mm)100100110120130140
Fork offset (mm)444444444444
Trail (mm) low/high126/122126/122126/122126/122126/122126/122
Bottom bracket drop (mm) low/high47/4042/3542/3542/3542/3542/35
Bottom bracket height (mm) low/high327/334332/339332/339332/339332/339332/339
Wheelbase (mm) low/high1168/11641188/11841212/12081241/12371280/12761315/1311
Standover (mm) low/high742/742742/742750/750753/753777/777784/784
Stack (mm) low/high618/614613/609623/618631/627639/640649/644
Reach (mm) low/high410/416430/435450/455475/480500/505530/535

Combine these with the 1,241mm wheelbase, 444mm chainstays, 65-degree head angle and 77.2-degree seat tube angle, and the high-speed potential is clear.

Its 130mm of travel has been tuned to perform on any kind of trail thanks to its progression, where the first part of its travel is soft and supple and the latter portion stiffer to resist bottom outs.

Specialized Stumpjumper Alloy Comp specifications

With parts from a host of big names, the Comp Alloy is good value for money.

Up front is Fox’s 140mm travel 34 Rhythm fork with GRIP damper that features external rebound damping adjustment and a progressive compression lockout dial.

The FSR suspension is damped by Fox’s Float DPS Performance rear shock, also with external rebound adjustment and a three-position compression adjuster.

SRAM takes care of shifting and stopping with its NX Eagle 12-speed drivetrain – with 11-50t cassette – and G2 R four-piston brakes with a 200mm front rotor and 180mm rear.

Specialized provides most of the rest of the kit, including the bar, stem and saddle, plus Roval wheels wrapped in tubeless-ready Butcher and Purgatory tyres. An X-Fusion Manic dropper post caps off the build.

Specialized Stumpjumper Alloy Comp ride impressions

Whether you’re pointing the Stumpy up or downhill, it feels remarkably calm and composed, with its geometry, suspension and components working in seamless harmony. This makes it a pleasure to ride all day long.

On seated climbs, the steep 77-degree seat tube angle puts your hips over the BB for comfortable pedalling.

Specialized Stumpjumper Alloy Comp trail mountain bike
The Stumpy represents one of the best value for money bikes you can currently buy.
Ian Linton / Immediate Media

The general seated position was well-suited to long days in the saddle, too. This meant I didn’t have too much weight through my hands and there was no front wheel lift or steering vagueness on steeper climbs.

I didn’t need to compensate for the geometry at all, and generating grip was intuitive and easy, not needing massive weight shifts or energy-sapping changes in body position.

Comfort was further enhanced by the smooth but massively supportive suspension, which absorbs trail chatter well and creates plenty of traction on rougher terrain.

It’s nice and progressive, so doesn’t sag deep into its travel on steep ascents and also resisted bottoming out as I rode over deeper and wider holes. This reduced the ‘nodding’ feeling bikes with softer or less supportive rear ends can suffer from.

There’s some pedalling bob with the shock in its ‘open’ position, but not enough to hinder progress.

Specialized Stumpjumper Alloy Comp trail mountain bike
There was plenty of pop for jumps and pumping, and loads of bump-smoothing suppleness.
Ian Linton / Immediate Media

Flicking the blue lever to ‘climb’ mode eliminates unwanted movement, but at the loss of some grip, so I left it in the open position for the duration of the test period.

On the downhills, the bike’s composure makes it a hoot to razz around manmade trail centre loops, off-piste singletrack and epic all-day cross-country routes alike.

The slack and long – for a trail bike – geometry means it is confidence-inspiring on the downs and combined with the powerful SRAM G2 brakes, I was able to push the Stumpy well beyond my expectations of what a 130mm-travel bike should be able to handle.

Specialized Stumpjumper Alloy Comp trail mountain bike
It was both fun and easy to corner at high speed.
Ian Linton / Immediate Media

Its suspension was super poppy and worked well no matter how hard or fast I was riding, too. When cruising down a trail, it had plenty of small bump sensitivity to improve comfort and grip, but also offered brilliant amounts of support halfway through the travel.

This meant I could pump and accelerate through holes without the bike feeling soft and wallowing. Bottom-out resistance was also good, especially when riding harder and faster.

It does have limits, but these are only reached once you start hitting much steeper or faster trails suited to enduro and downhill bikes.

I found the bottleneck in performance wasn’t down to its geometry, but the flexy-when-pushed Fox 34 fork.

This tended to tuck or twist when loaded up in sharp turns with steep run-ins, and its simple GRIP damper struggled to provide enough mid-stroke support unless I ran higher spring rates than recommended.

Specialized Stumpjumper Alloy Comp trail mountain bike
Its geometry meant it was a highly capable bike no matter the terrain.
Ian Linton / Immediate Media

Upgrading to a 150mm-travel Fox 36 would unlock a whole lot more potential and make this excellent generalist even more capable.

That’s not to say it performed badly, in fact, quite the opposite was true. It was really intuitive to ride thanks to the great relationship between hands and feet that made me feel like I was ‘in’ the bike rather than ‘on’ it.

Specialized Stumpjumper Alloy Comp trail mountain bike
The Stumpy was not only smooth on trail chatter, but resisted big bottom outs and had plenty of mid-stroke support.
Ian Linton / Immediate Media

The Specialized Butcher and Eliminator combination were great on trail centre style runs regardless of the weather, but did tend to come unstuck on boggier terrain, although that was expected given their tread pattern.

The Code G2 brakes performed well and offer good levels of stopping power and I was impressed with the comfort offered by the Specialized Bridge saddle and own-brand grips.

Specialized Stumpjumper Alloy Comp bottom line

Specialized Stumpjumper Alloy Comp trail mountain bike
The geometry is virtually faultless.
Ian Linton / Immediate Media

Overall, the Stumpjumper Alloy Comp rides impressively well, even when compared to lighter, more expensive bikes with flashier specs.

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It’s good value for money, too, and the seriously capable frame means that a few choice component upgrades down the line would help unlock new levels of performance.

How we tested

We put four do-it-all full-sus trail bikes, at the super competitive price point of £3,000, to the test on our local trails to find out which is the best you can buy right now.

Trail bikes are designed to handle everything from bridleway bashing to the odd uplift day, but categorising a trail bike by its geometry or suspension travel is becoming harder because bikes are getting lower, longer and slacker with more squish.

Generally, though, you should expect 130mm to 150mm of travel, plenty of standover room, a decent reach (the horizontal distance from bottom bracket to head tube, which affects how a bike feels when stood up on the pedals) and a stable head angle, between 64 and 66.5 degrees.

Also on test

Product Specifications


Price br_price, 5, 3, Price, EUR €2999.00GBP £2500.00USD $3500.00
Weight br_weight, 5, 6, Weight, 14.96kg (S4) – without pedals, Array, kg
Brand br_brand, 5, 10, Brand, Specialized


Available sizes br_availableSizes, 11, 0, Available sizes, S1, S2, S3, S4, S5, S6
Bottom bracket br_bottomBracket, 11, 0, Bottom bracket, SRAM DUB
Brakes br_brakes, 11, 0, Brakes, SRAM G2 R, 200/180mm rotors
Cassette br_cassette, 11, 0, Cassette, SRAM NX Eagle, 11-50t
Chain br_chain, 11, 0, Chain, SRAM NX Eagle
Cranks br_cranks, 11, 0, Cranks, SRAM NX Eagle, 30t
Fork br_fork, 11, 0, Fork, Fox 34 Float Rhythm, 130mm (5.1in) travel
Frame br_frame, 11, 0, Frame, Aluminium alloy, 130mm (5.1in) travel
Grips/Tape br_gripsTape, 11, 0, Grips/Tape, Specialized Trail
Handlebar br_handlebar, 11, 0, Handlebar, Specialized, 800mm
Headset br_headset, 11, 0, Headset, FSA
Rear derailleur br_rearDerailleur, 11, 0, Rear derailleur, SRAM NX Eagle (1x12)
Rear Shocks br_rearShock, 11, 0, Rear Shocks, Fox Float DPS Performance Rx Trail Tune
Saddle br_saddle, 11, 0, Saddle, Specialized Bridge Comp
Seatpost br_seatpost, 11, 0, Seatpost, X-Fusion Manic, 170mm
Shifter br_shifter, 11, 0, Shifter, SRAM NX Eagle
Stem br_stem, 11, 0, Stem, Specialized, 55mm
Tyres br_tyres, 11, 0, Tyres, Specialized Butcher GRID GRIPTON 29x2.3in (f), Specialized Purgatory GRID GRIPTON 29x2.3in (r)
Wheels br_wheels, 11, 0, Wheels, Roval