We got our hands on a Specialized Stumpjumper FSR Comp 6Fattie recently, courtesy of Specialized Asia Pacific, and a series of braaps, skids, thuds, cranks, swooshes … more brrraaaapps followed. Obviously we had some fun with this up-sized brother of the regular Stumpy. A whole lot of talks and thoughts followed and this was what we concluded about this handsome Plus Bike.




Not too long ago, we heard about the emergence of Plus Bikes. "A novel niche" – some commented. But give it some thought, it seems a natural evolution for product designers and bicycle companies. For a long while, our mountain bikes have been more or less limited to wheels that are up to 2.5 inch wide – any wider and it wouldn't fit onto the frame. To add to the barrier, it's not like we could find 2.6 or wider tires for typical mountain bikes easily back then anyway. Then came the fat bikes with their chunky tires which grew a bit wider over time too. In the course of natural evolution, an equilibrium point has to form eventually. A sort of conclusion happened for the "tire width evolution" came when the bicycle designers decide to pick the virtues of both traditional mountain bikes and fat bikes. Thus the emergence of the Plus Bikes.

Plus bikes come in 27.5+ and 29+ wheel sizes. While much of the earlier design objectives and evolution center around the studies of the tougher to perfect 29+ bikes, it seems like 27.5+ bikes unwittingly benefited from all the goodness and emerged the favored child of the two.

While manufacturers were eager to develop their own Plus Bikes and were also quick to preach their bikes' unique propositions, their views were somewhat varied – from selling it as a true adventurer's bike, to an agile monster truck of the mountain bike world and to being the future for mountain biking, where the best bits from every kind of bike are now meshed into the one bike to rule them all. Such differing views do more confusion than inform us about why we should own a Plus Bike.

We intend to embark on our own study starting from the Specialized Stumpjumper FSR Comp 6Fattie – which in fact, is not a fat bike, but a 27.5 x 3 inch fat-enuff-and-wide-wheeled Plus Bike.




The Specialized Stumpjumper FSR had came a long way. It is one of the most popular trail bikes ,with superb handling and proven FSR linkage system. It has been the recipient of Specialized's technology improvements from the early development of their full suspension FSR research too. Over the years, the Stumpjumper FSR has refined itself in terms of geometry, linkage design and other add-on innovations to near perfection. And now, with the introduction of Boost 148 rear axle standard, much of the former problems which came with building Plus Bikes were quickly solved. To name a few: outboarding cranks to optimize chain line, options to install bigger chain rings, maintaining short chain stay designs or simply being able to fit wider tires than before. The stumpjumper 6Fattie is supposed to come with all these solutions, and in addition, deliver what is believed to be a package of pure, dialed mountain biking fun! 

Specialized positioned the 6Fattie as a hardy trail bike that can "squeeze every last ounce of fun out of the trail". The Satin Gallardo Orange / Black 135 mm travel 6Fattie Comp frame is made from M5 alloy and is also the plaform to introduce the 6Fattie wheel system – which is actually taking a set of 27.5 inch wheels and wrapping them with some big-@$$ 3 inch quick rolling Specialized (Purgatory Control front and Ground Control rear) tires. Some parts to note about the 6Fattie includes internal cable routing, 148 mm dropouts, sealed cartridge bearing pivots and replaceable rear derailleur hanger. The Fox Float Performance DPS rear shock features the useful autosag function. Autosag, in short, is Specialized's one-click, nearly automated way of setting the rear shock to the rider's optimal sag at stationary position really quickly. A really innovative and useful feature. The front end suspension of the bike is taken care of by a set of 150 mm Fox 34 Plus Performance fork which has 3 positions of compression adjustments.

With a Head Angle of 67 deg, the 6Fattie is built to be a responsive bike that works well for a bike with fatter than normal tires. Imagine a bike with wide tires and a overly slacked out Head Angle – we would suspect that a bike with too slack a head angle running on wide tyres would be too draggy and a pain to climb with. That would defeat the purpose of a Plus Bike.

The 6Fattie's effective Top Tube length of 563 mm (Small size frame) and a 74 deg Seat Tube angle mean that its cockpit lies within the commonly accepted level of spaciousness, comfort level and rider's fit. This bike (size small) has a typical trail bike's wheelbase of 1122 mm – again tending towards the fact that this bike doesn't aim to be an exceptional descender but aims more for all-round performance and sure-footed control.

All the frame sizes of 6Fttie feature a 437 mm chainstay rear triangle which is considered short for Plus Bikes standards. Again, we are thus expecting a bike that is easy to control and has a reasonable amount of playfulness.




Before we start our review, we did a quick setup routine with the 6Fattie. For the fork, we tuned it to 25% sag of the rider's weight and rear was set to 30% sag. The CTD setting for both the front and rear shock were set to trail mode throughout the ride as we felt that the descent mode was a tad too soft, allowing the shock to blow through its travel too easily – and that was based on our lean small sized frame-compatible rider. Tires were pumped to 15 PSI for front tire and 18 PSI for the rear.



On the descent, the 6Fattie is predictable and well-behaved, soaking up the terrain as expected – thanks to the well designed FSR linkage. While the 6Fattie was bombing its way downward, we were extremely happy with its braking versus chain (torque) independence. Brake jacks and squats, if any at all, were very minimal. The FSR system works well regardless of our pedaling during descent. On occasions that we did pedal as we were moving downhill, the suspension did its work as expected and yet allowed us to continue delivering more torque to gain better speed as we go. All this while staying within the good control threshold with little or no misbehavior from the bike. By this, we mean very little pedal kickback and just the right amount of anti-squat throughout the ride. No doubt a well dialed suspension system that is very neutral. In the ever-so-often incident of unexpected potholes and other trail chatters, the bike held its line very well and cushioned irregularities with confidence. However, all praise aside, we have to bear in mind that this is a trail bike fitted with some oversized wide wheels. It's stable, and feels good on the control area, yet it's trail geometry would mean it has its weakness. It is still not a full replacement for a downhill or enduro bike when it comes to descents (and that would be an unfair comparison already).



On the ascent, we tried riding up the bike with 2 different riding styles over a same section. We could conclude that the 6Fattie enjoys long fun rides and prefers the efficient riding option when it comes to tackling climbs. On our attempts to mesh our way up a slope, we didn't really like the outcome. The bike bobbed when we stood and meshed our way up. This made us lose precious energy quickly and increased our heart rate to inefficient levels. We then tried the same section with the seated climb method, adjusting the gearing to a ratio where we were happy with both the speed and the effort. Spinning consistently got us up the same section fast and efficiently when we engaged the optimal gear ratio, and with more than enough energy to maintain speed and push on faster once the slope was cleared. Even in the case where we hit slightly off the normal course and had to deal with some additional or unexpected holes, rocks or roots, the 6Fattie simply monstered over them with some playfulness that would put a smile on our faces. (At least for the first few rides when we just discovered just how fatter tires can eat up the terrain). This is one case where we have to agree that understanding the properties of a bike's design and utilizing it's strength get us an edge over any would-be competition.



We are well aware that Specialized has been finetuning their FSR shock system for many years and it now has very little weaknesses which were more obvious on earlier Specialized bikes. But for the current FSR, we would hope that its behavior is a little more progressive. The current system is very linear. Of course, we do take into consideration that suspension behavior preference could be quite personal. And for the leisure non-competitive rider, comfort and efficiency is often of higher priority as compare to outright competition level speed. Not that speed is not important to a non-race rider, but consideration for speed may not be the only factor attributing to their shock tune and dampening preference. Our preference for more progressive shock behavior also explains why we left the shock at Trail mode throughout the ride.




One complaint we have with the 6Fattie Comp is the width of the rims. It is a tad too narrow for a Plus Bikes. The result is a rounded wheel profile. While this is still alright for the rear wheel setup, the front wheel tends to break traction unexpectedly (based on the tire pressure and expected performance of the Purgatory Control). The rear wheel, with its tire width, holds its line well and is able to break and regain traction on "command".

The Specialized tires compound and build is of the right hardness – we like it! The 6Fattie does not feel like a Fat Bike in any way. While the bike is a little more bouncier than typical trail bikes, it feels fun, comfortable and behaves more like a trail bike than a fat bike. We totally like this bike's ride feel. The only occasions when we felt sketchy on the bike was when we leaned hard into corners or when we landed on angled surfaces. We were worried that the front tire might burp anytime (if it is running tubeless).

The SRAM drive train might be be the weakest link on the bike. We felt the rear deraileur's clutch fail as we rode (this being not a first time we experienced this from similar SRAM products). But as of all SRAM drive trains, the shifting is crisp and sharp. With 11 speed, the drivetrain gave us practically all the gears that we would ever need for the trail. For stronger riders, the front 28T chain ring may not satisfy and we recommend going for a slightly bigger chain ring if rider has the strength and stamina for it. But do bear in mind that this is a Plus Bike, which means that the ride does feel a little draggy as the distance pile up.

The Shimano brakes works like a regular dream. We expected it to work that well and it delivered what was expected – light pressure on the brake levers for braking modulation, squeeze hard to jam the brakes to lose some traction when you are up for it and then let the tires do their part to regain control. Controlled fun!

The use of a short stem is clever. It helped to give the bike a more agile and responsive steering feel. But the handle bar's backsweep seem more than it's stated specification of 8 deg. The grips were too skinny for our liking and has a tendency to be slippery when wet.




Specialized believes that a beautiful bike, just like a beautiful sport car, should do away with unsightly hacks that riders are so used to over the years. Like cable-tying a spare tube to the frame or other stuff that is needed for the ride. SWAT is Specialized solution for this. The term is an acronym for Storage, Water, Air and Tools, and SWAT technology incorporates bikes, riders, and equipment by putting all necessities in a clean, sleek, and aerodynamic location.

The 6Fattie does not come with the widely viral and heavily advertised down-tube storage nor does it have other hidden storage areas. But some optional accessories fitted in nicely on the bike and we thought it was really clever and made the bike a lot more slick yet functional.




With the SWAT concept going on strong, riders can now choose to use Specialized bottle cages that comes with a a set of emergency multi-tool.The multi tool can be fitted onto any SWAT-compatible bottle cage for easy, no-hassle transport and storage. On the tool, is an array of Allen keys and a Torque wrench which takes care of most of the trail side fix needs. And there is a choice of bottle cage opening on either the left or right side (depending on rider being left or right handed)! More information here.



Another clever accessory is the Mountain Bandit – a spare tube, CO2 canister and tire lever kit that can be bolted under SWAT compatible saddles. The kit features a simple, Velcro strap with individual compartments for the tire kit. It is easy to access everything and everything is packed in one simple package. For Plus Bikes, this would be an important safety tool should you have an emergency. The probability of bumping into a fellow Plus Bike rider in the trail whom you can borrow a spare tube from, is still relatively low currently. More information of the Bandit here.




We love this bike. Brushing all the marketing pitch aside, we just feel that this bike makes us happy riding it. It eats up obstacles yet gives enough feedback. It rides neutral yet inspires confidence for some  brapping at the right time. The small hitches we experienced were minor component peeves that could be solved with simple swaps. The main structure and design of the bike – the frame itself, geometry and suspension design are the stuff that lingers fondly with us.

This may not be that race bike that would work as a do-it-all if you intend to join every race around your region. But if you are interested in riding this bike to places, smooth trail, technical trails, slowing down sometimes to soak in the cool technical terrain and speeding up at other times to flow with the trail, then this bike is probably one of your best bet – regardless if you are a newbie or an experienced rider.

We feel Plus Bikes are here to stay – alright, this is our personal opinion but the facts all point towards this outcome. In the near future, there would be no lack of tire choices and spares for us to choose from. 

Bikes should be fun. And this bike nailed that part straight up! Further blessed with a cool masculine silhouette, this bike definitely turns head and allow the rider to show his salt at the trails. Go get the fun!



Demo bike by Specialized Asia Pacific Pte Ltd. 

All photos by Bikezilla.