SPECIALIZED STUMPJUMPER Comp Carbon 27.5

The trail bike category is evolving rapidly. Bikes are longer, slacker, and lower than ever. Specialized introduced the most recent Stumpjumper just four years ago, but that period saw some of the most significant innovations in bike geometry since mountain biking began. As a result, the Stumpjumper looked rather conservative amongst its more radical peers, and as a brand with the mission ‘Innovate or Die’, Specialized had to change something.

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So what’s changed? Well yes, the new Stumpjumper is a little longer, with a 455mm reach on the large frame, and slacker—66 degrees at the head tube—with a 342mm bottom bracket. Meanwhile the chainstays are longer at 432mm, taking the wheelbase out to 1212mm. But this isn’t a bike you can read by the numbers alone. There’s a lot going on here, and while it’s not particularly radical from a geometry point of view, it’s a machine that’s been carefully and completely reengineered from the ground up.

The Frame

The new carbon frame’s most significant feature is the asymmetric ‘side arm’ design, borrowed from the Demo. This is intended to laterally stiffen the frame and adds material around the upper pivot of the FSR suspension design. Specialized claims it also connects all three mounting points of the rear end and shock on the frame, minimising frame flex when the rear suspension is active.

The rear triangle is now also carbon and features a seatstay bridge to add stiffness. This new assembly helps shed over 500 grams over the previous frame. Hub spacing is 148 and there’s room for tyres up to 3.0”.

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One of Specialized’s claims at the bike’s launch was “no proprietary BS”. Gone is the much-criticised custom shock mount, which limited alternatives to the stock shocks. Gone is Autosag, which heavier riders often found under-sprung. The new frame will accept any standard 210 x 50mm metric size shock. A flip chip in the upper linkage allows you to slacken the head angle by an additional half degree and further lowers the bottom bracket. The bike also uses the same size bearing in each pivot, making replacement simpler if required.

Home mechanics will rejoice as the press-fit bottom bracket has been replaced with a threaded version, and the internal cable routing has been very cleverly designed with tubes that run right through the frame from head tube to rear brake and derailleur. Simply feed in the hose or cable at the front and it will appear at the other end without the need for magnets, broddling sticks or profanity.

 Specialized’s clever SWAT system is clean, simple and hassle-free.

Specialized’s clever SWAT system is clean, simple and hassle-free.

The SWAT box in the down tube is slightly larger, and the bottle cage/cover is simpler and easier to fit. This is no gimmick. It’s the only effective solution I’ve come across to riding without a pack. Strapping items to your frame is a poor substitute. We easily fitted a tube, pump, chain breaker, link, energy bar and a couple of emergency gels in with room to spare. It doesn’t rattle and your frame isn’t sandpapered by a mineral-infused, clearcoat-wrecking strap. The cage holds a mini-tool and there’s space for a full sized bottle. There are also fittings for a chain guide and the new chainstay protector is designed to interrupt chain slap. It’s all very well designed, engineered, and thought through.

The Kit

The Comp model is fitted with a Fox 34 Rhythm fork. It’s Fox’s OEM trail model, but it’s very effective. Sure, it doesn’t have the Kashima coated stanchions or the bells and whistles, but it works well and is easy to live with.

The rear shock is a Fox Float DPS performance model with a 3-position compression lever and Specialized’s Rider Experience tune.

The contact points are all from Specialized. The 780mm wide bar is a good width and comfortable shape, clamped by a 45mm stem, and the Body Geometry Phenom saddle deserves a mention for being a very comfortable perch.

I wasn’t expecting much from the X-Fusion post, but it’s surprisingly good. The 34.9mm seat tube means you’re less likely to be swapping to your favourite dropper, but there’s simply no need. This post worked brilliantly through fair weather and foul. The composite lever feels great, the 160mm drop gets the seat right out of the way and the action is very smooth.

The Roval rims have a 29mm internal width and are laced to a pair of Specialized branded hubs. These are clad with Specialized’s excellent Butcher and Purgatory tyres. Both feature the reinforced Grid sidewall and are ‘Goldilocks’ 2.6” wide.

A Shimano XT rear derailleur is actuated by SLX shifters, and Race Face Aeffect cranks with a 32T ring turn an SLX 11-46T cassette. SLX brakes are deployed to slow things down.

So how does it go?

This is a really fun bike to ride. If you simply must have the longest, slackest sled on the market, you’re going to want to look elsewhere (the new Stumpjumper Evo, for example). But Specialized are betting that not everybody wants a slacked-out chopper. What’s been produced here is a very impressive, well-rounded trail bike.

When climbing, the very linear rate of the shock on the previous model tended to loathe out of the saddle efforts, preferring a steady, seated climbing style to avoid pedal strikes. The new bike’s kinematics and shock tune are a significant improvement, and even with the shock’s platform lever fully open, mashing the pedals sees little bobbing and the bike surges forwards.

But it’s heading downhill where this bike really shines. It comes alive in twisty singletrack and invites you to throw it deep into corners. The frame is noticeably stiffer laterally than the old bike and it tracks exceptionally well. The ‘not quite plus’ 2.6” tyres deliver grip in spades, noticeably more than narrower rubber but without the disconcerting squirming and uncontrolled rebound that larger tyres can be guilty of.

In roots and rock gardens, the classic pitter-patter feel of the FSR suspension is still there but it’s more supportive and progressive than before, which rewards hard riding. The Stumpjumper has always been plush, but it had a tendency to blow through the mid-section of the travel too quickly. This bike is also smooth, but it feels more purposeful and confident at the same time. The extra length and slacker head angle give it greater poise at speed while retaining a flickability that keeps the bike agile and great fun yet still allowing it to be pushed hard in technical terrain.

What’s also noticeable is that this is a very quiet bike to ride. How much of that is down to suspension and how much to the new chainstay protector, I can’t say, but there’s very little noise, even over very rough sections.

Is it an improvement on the previous iteration? Absolutely. Has Specialized done enough to ensure the Stumpjumper is a serious contender in the trail bike category? Definitely. You can tell a great deal of thought has gone into the design process and the result is a well-executed contemporary trail bike. I’ll miss it when I give it back.

Would I change anything? Not much. While the gearing is fine for purpose-built trails, out there in the backcountry there are climbs I know will have me walking with the 32 x 46 low gear. Would I swap the carbon rear end for the added range and lower gear of SRAM’s GX Eagle? I’m not sure, and it’s not a choice on offer. You could drop to a 30T ring, but lose out at the high end. Or simply aim high and buy the Eagle-equipped Expert spec model, which also features a Roval carbon wheelset.