Specialized S-Works Stumpjumper 6Fattie review£6,500.00

This one will make you believe the plus-sized hype – really

BikeRadar score4.5/5

Bicycle tech editors don’t exactly have to put a hand on the Bible when they sign up for the gig. In essence though, it’s my sworn duty to filter through the piles of propaganda that marketing and PR folks constantly fling in our direction.

When it comes to hype, few companies generate as much internet skepticism as Specialized (however unjustified it often is) and few trends are lambasted as pure marketing BS as much as the new crop of so-called ‘plus’ bikes. Call me a shill, label me a sellout, and cast as much anonymous keyboard ire as you want my way. But after riding the new S-Works Stumpjumper 6Fattie (which will retail for a whopping $8600 / £6,500) just call me a believer.

Related: Specialized Stumpjumper 2016 - first look

Bootleg Canyon – the chosen demo grounds for the annual Interbike trade show – is the mountain bike trail equivalent of Australia. Everything here is trying to kill you. The terrain is made up almost entirely of decomposed lava rock, there’s virtually no traction anywhere, and whatever hasn’t been pulverized into wheel-sucking kitty litter is razor-sharp and just waiting to slice you to the bone. It’s challenging for sure, but generally not my first choice of a place to spend a few hours.

The chassis is the latest incarnation of specialized’s highly evolved stumpjumper trail platform: the chassis is the latest incarnation of specialized’s highly evolved stumpjumper trail platform
The chassis is the latest incarnation of specialized’s highly evolved stumpjumper trail platform: the chassis is the latest incarnation of specialized’s highly evolved stumpjumper trail platform

The chassis is the latest incarnation of Specialized’s highly evolved Stumpjumper trail platform

In fact, I usually hate riding here (especially when it’s swarming with Interbike attendees).

After rallying the Stumpjumper 6Fattie for nearly two hours, however, I was having so much fun that I didn’t want to get out of the saddle.

With this thing underfoot, Bootleg Canyon’s notorious lack of grip through corners was almost completely neutralized by the giant footprint produced by the 3in-wide rubber (inflated to just 15-16psi). Inside of nervously sliding through turns, I found gobs of reliable traction – and when the treads did break loose, they did so in a predictable fashion that was easy to correct.

While the cornering traction was impressive, the bike’s tenacity on climbs was even more so. Save for one particularly challenging uphill switchback (that even the legendary Ned Overend couldn’t clean), all I ever had to do was pedal. Standing or seated, the 6Fattie consistently clawed its way up any number of stepped, loose, and/or rocky climbs with ludicrous ease. All I had to do was keep applying the power.

The oversized treads make for a super cushy ride: the oversized treads make for a super cushy ride
The oversized treads make for a super cushy ride: the oversized treads make for a super cushy ride

The oversized treads make for a super cushy ride

Finally, there’s also an undeniable comfort benefit to the oversized treads. I’ve ridden plenty of bikes with ultra-compliant suspension but this thing is just stupidly cushy. It’s not a magic carpet; it’s one of those mega-fuzzy rugs with the big woven tendrils that make you feel like you’re lying on a foot-thick layer of freshly shorn sheep’s wool.

Bootleg Canyon is filled with endless minefields of embedded momentum-killing rocks but this time around, they were completely erased as if they weren’t even there, wholly swallowed up by the bulbous casings. Smaller trail debris is absolutely erased and whatever remains is adeptly handled by the suspension travel.

What was perhaps best about my brief test ride, however, was how eerily normal the bike felt. Unlike true fat bikes, which typically handle awkwardly (at least to some degree) and unfailingly cumbersome in non-winter conditions, the 6Fattie delivers a light and natural feel through the bars with no auto-steer to speak of. Much of the credit likely goes to Specialized’s somewhat unlikely choice of wheels and tyres.

The Ground Control 6Fattie tyres’ low-profile tread and reasonably supple casing yield surprisingly low rolling resistance. Instead of the roughly 50mm-wide rims fitted to most plus bikes, though, Specialized instead sticks to ones measuring just 29-30mm between the bead hooks. This produces a super rounded casing profile that makes it easy to transition the bike from edge to edge and a light feel on center (while also decreasing rotating mass).

There's 150mm of movement up front courtesy of a fox 34 plus factory fork: there's 150mm of movement up front courtesy of a fox 34 plus factory fork
There's 150mm of movement up front courtesy of a fox 34 plus factory fork: there's 150mm of movement up front courtesy of a fox 34 plus factory fork

There's 150mm of movement up front courtesy of a Fox 34 Plus Factory fork

It’s also surprisingly easy to get the bike rolling despite each tyre weighing upwards of 1kg – although it certainly didn’t hurt that the high-zoot S-Works version sampled here weighed just 12.7kg (28lb, without pedals).

The tyres are still heavier than usual and do have more of a gyroscope effect than more normal-sized treads, but I didn’t find it particularly troublesome. Aside from that, this thing behaved like any other trail bike with no mental adjustments needed on my part aside from recalibrating traction limits.

Tyres aside, what lies beneath is the latest incarnation of Specialized’s highly evolved Stumpjumper trail platform. There’s 135mm of nicely controlled travel out back (with damping duties handled by Fox’s latest Float Factory DPS rear shock) and 150mm of movement up front courtesy of a Fox 34 Plus Factory fork. Together, they do a great job of largely canceling out the bounciness inherent to big-volume tyres, with the exception of harder landings and g-outs where you can still get bucked off-line if you’re not mindful.

As I’ve come to expect from the Stumpjumper family, handling is stable and neutral with a low-slung stance and not-too-slack 67-degree head tube angle, while the slightly wider Boost 148mm rear hub spacing allows for a reasonably short 437mm rear end that makes it easy to loft the front end as needed.

The main swat door houses a mini-pump and tube: the main swat door houses a mini-pump and tube
The main swat door houses a mini-pump and tube: the main swat door houses a mini-pump and tube

The main SWAT door houses a mini-pump and tube

Since the carbon front triangle is shared with the standard Stumpjumper 29er, too, there are also bonus features like the SWAT Door (which allows a mini-pump and tube to reside inside the down tube), a tidy micro-chain guide that bolts directly to the frame, a mini-tool that attaches just ahead of the forward shock mount, and more than enough room inside the main triangle for a large water bottle.

Am I totally converted to the plus side? As much as I enjoyed the S-Works Stumpjumper 6Fattie, I’d say not quite yet. Those low tyre pressures are still susceptible to pinch flats and rim damage (I bottomed the rear tyre several times on sharp rocks), there’s no escaping the additional weight of all that rubber, and there’s almost so much traction that it can almost make some types of trail riding seem a little mundane (although that’s likely dependent on individual riding styles).

That said, I found this bike’s advantages to far outweigh any negatives, and it was way more fun than any plus-sized hardtail I’ve ridden to date. I’m normally pretty ambivalent when test product shows up on the doorstep but I might just let out a little giggle when brown Santa drops this long-termer off.

The ground control 6fattie tires' low-profile tread: the ground control 6fattie tires' low-profile tread
The ground control 6fattie tires' low-profile tread: the ground control 6fattie tires' low-profile tread

The Ground Control 6Fattie tyres' low-profile tread

James Huang

Former Technical Editor, US
James was BikeRadar's US tech editor from 2007-2015.
  • Age: 40
  • Height: 173cm / 5'8"
  • Weight: 70kg / 154lb
  • Discipline: Mountain, road, cyclocross
  • Preferred Terrain: Up in the Colorado high-country where the singletrack is still single, the dirt is still brown, and the aspens are in full bloom. Also, those perfect stretches of pavement where the road snakes across the mountainside like an artist's paintbrush.
  • Beer of Choice: Mexican Coke
  • Location: Boulder, CO, USA

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