Review: Trek Fuel EX 9.9 29

Frame Details

The Fuel EX's full carbon frame has a clean and modern look to it, with a subtle curve to the top tube that provides plenty of standover clearance while also leaving room to mount a water bottle inside the front triangle. The brake, derailleur, and dropper post housing are all tucked neatly out of the way inside the frame thanks to Trek's Control Freak system. Control Freak is one of the better internal routing configurations out there, offering nearly unlimited options for running housing through the modular rubber ports found on either side of the headtube. There are also two slits in the downtube that a zip tie threads through to cinch everything together and eliminate any potential rattling inside the frame.

Boost 148/110

Last year's Remedy was the first bike on the market to feature Boost spacing, a rapidly emerging standard that uses a 12x148mm rear thru-axle hub instead of the 12x142mm spacing that preceded it. Boost has spread to the front end as well, where 10 millimeters have been added onto the total hub width, bringing it up to 110mm. In both cases, one of the overarching goals is to increase wheels stiffness, based on the theory that wider hub flanges will improve the spoke's bracing angle, and in turn create a stronger wheel.


Geometry




Suspension Design

The Fuel EX uses Trek's Active Braking Pivot (ABP) suspension design, which is used on everything from their downhill race rigs to XC speed machines like the Top Fuel. ABP uses a pivot that rotates around the rear axle, with the intention being to prevent braking forces from affecting the rear shock in any way. The shock itself isn't attached to a fixed point on the frame; instead, it's attached to the chainstay and the upper rocker link, allowing it to 'float' for what Trek says is increased sensitivity.

Keen observers will have noticed that the rear shock no longer has the upper top hat shaped portion that housed Trek's proprietary Dual Control Valve (DRCV) technology on previous models. Where did it go? It turns out that FOX's new Extra Volume (EVOL) air sleeve closely mimics the feel of DRCV, which allowed Trek to turn their attention to including their new RE:aktiv shock technology on as many models of the Fuel as possible.

Developed through a collaboration between Penske, FOX, and Trek, RE:aktiv was designed to improve a bike's pedaling performance without diminishing its ability to absorb impacts. A spring loaded valve inside the shock body allows for increased low speed compression for pedaling support on smoother terrain, but when the shock's shaft speed increases the valve opens up, enabling the shock to quickly and smoothly absorb the impact before the valve closes again. This action happens in all three compression settings, in theory allowing rides to choose how much pedaling support they want without worrying about being jarred by larger impacts.

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Setup

The Fuel EX is extremely well specc'd out of the box, which should be a given considering its price tag, but there are a few little tweaks that can transform it into even more of a hell-raiser out on the trails. The first order of business is to swap the 70mm stem for something shorter, preferably 50mm or less. I know, you've heard this before, and everyone has their own preferences, but trust me – it's worth it out on the trail for the added control, especially when gravity takes over.

The next step is optional, but recommended if you spend any time in loose or wet terrain: install a meatier tire up front. The XR3 tires are solid performers across a wide range of conditions, but running a beefier tire like the Bontrager SE5 or something similar helps considerably in more technical terrain. Plus, by keeping the lower profile tread in the rear the bike's rolling speed isn't affected as much.

Setting up the suspension is a straightforward process, and to make things even easier Trek has a suspension settings calculator on their website. Simply select the bike model, input your weight, and with one click the suggested air pressure and rebound settings for the fork and shock will be displayed. The suggested shock pressure, 20 pounds above my body weight, ended up being exactly correct for me, although my final fork settings were a little softer than what the program displayed. In any case, it's a good place to start before adjusting things to match your personal preferences.


Climbing

Switching from a heavier all-mountain bike to the Fuel EX creates the same instant feeling of buoyancy that a deep sea diver experiences after shedding his weight belt and rocketing to the ocean's surface. 24 pounds is remarkably light for a 120mm full-suspension 29er, a number that's made even more impressive by how stiff and flex-free the frame is. Trek claims that the overall frame stiffness has been increased by 14% over the previous version, and although I don't have any way to precisely verify that number, I'm inclined to believe them based on my experiences out on the trail. Standing up and sprinting, hitting a natural hip jump into a root-filled landing, pushing hard into a bermed turn – in all instances the bike felt extremely solid, and much more composed than I would have expected given its weight.

Unlike their longer and slacker enduro relatives, trail bikes are expected to exhibit better than average climbing manners, and in this regard the Fuel EX 9.9 doesn't disappoint. It'll scamper up just about anything in its way with a surefootedness that helps keep the rear wheel firmly planted on the ground even on loose terrain. Even with a short stem installed it was easy to keep my weight distributed properly, and there was never any front wheel wandering on steep climbs.

There is a modest amount of suspension movement if the shock is left wide open, especially when standing up and mashing on the pedals, but this can be counteracted by flicking the rear shock's blue lever to the central low speed compression setting. I rarely used the stiffest Climb mode, but the beauty of the RE:aktiv damper is that even in the firmest setting the shock will still absorb impacts, which allows for more traction compared to a shock that fully locks out. Plus, if you do forget to switch out of Climb mode before heading downhill there's not going to be the jarring, my-fillings-are-going-to-rattle-out feeling that can occur on a shock with a traditional lockout.

With a 40 tooth cog as the easiest gear out back and a 32 tooth ring up front, the Fuel's gearing is a bit tall for a 29er, but luckily the bike's light weight helps to counteract this minor inconvenience. For riders that do find themselves wanting to spin more than stand on the steepest ascents, Race Face's direct mount chainrings are extremely simple to swap out, and a 30 tooth ring up front would make an appreciable difference.



Descending

Okay, so a 24 pound carbon 29er climbs uphill well – that's not exactly surprising. It's what happens after the climbing ends that really matters, and once again the Fuel EX delivers. While it may not possess the same margin of error that's present with the Remedy, its longer travel sibling, the Fuel EX still dishes out a smooth and controlled ride, even on rougher terrain. The feel of the Float 34 up front matches that of the rear shock, and there's plenty of support to keep the bike from going through all 120mm of travel too rapidly.

A 68.8° head angle keeps the Fuel's handling on the quicker side of things without being twitchy, and the shorter chainstays (compared to the previous version) make it easier to get the back end around sharp turns. As a whole the bike feels extremely well balanced, placing the rider in a neutral position between the wheels, ready for whatever comes around the next twist in the trail. It does have its limits, but it takes a seriously rowdy trail before it starts to get rattled, and even then it's usually just a matter of easing off the throttle ever-so-slightly to avoid getting ping-ponged off line. Remember, this is a trail bike, and Trek has other bikes in their line for riders that are more focused on the downhill portion of the riding equation. I did find myself wondering what a 130mm fork would feel like, which is how the aluminum Fuel EX 9 comes equipped. That extra 10mm of travel would slacken the head angle a touch, and likely add a bit more stability in the steeps, pushing the Fuel more towards the Remedy's territory.

As far as jumping goes, depending on who's asking I may or may not have ridden a lap on Whistler's A-Line just to see what would happen. You know, for science. It turns out that hitting big jumps on a bike this light is a wildly good time, albeit one that's well out of the realm of the Fuel's intended purpose, and not something I'd suggest making a habit of doing. All the same, the capabilities of this carbon machine are downright amazing.



Component Check

• FOX Float 34 Factory fork: On my first couple of rides aboard the Fuel EX I wasn't able to get full travel out of the Float 34 no matter how hard I tried, so I removed two of the yellow volume spacers from the air spring side of the fork, a quick adjustment that made all the difference. Smooth, supportive and precise, the Float 34 is an ideal match for the Fuel EX, and the ability to adjust the low speed compression in the fork's full open mode mode is a welcome improvement.

• XTR Brakes: For the most part, the Fuel 9.9's build kit was flawless, but the XTR brakes gave me trouble. I ended up bleeding both the front and rear brake to try and achieve a more consistent lever feel, but still couldn't get them to pull to the exact same spot each time. One pull would have the lever going through ¾ of its stoke, and the next would have it moving halfway before the pads contacted the rotor.

• Bontrager Evoke RXL seat: Seats are always going to be a matter of personal preference, but I found the Evoke RXL to be extremely comfortable, with a supportive shape and just enough cushioning in all the right places.

• DT Swiss XMC 1200 wheels: The XMC 1200s held up well to everything I tossed at them, and despite the hard use they saw there was never a need to put them on the truing stand. Even if they had needed an adjustment, the nipples easily accessible on the outside of the rim, which isn't always the case with high end carbon wheels. The 24mm internal rim dimension isn't pushing the boundaries as far as width goes, but there was still plenty of support for 2.3” tires without any burping or rolling the bead off the rim.




Pinkbike's Take:

It's hard to think of a rider who wouldn't have fun on the Fuel EX. This is a bike that could easily toe the line at a local XC race one day and take on a rugged backcountry loop the next without missing a beat. Its trail manners are impeccable, a shining example of how a modern trail bike should behave. - Mike Kazimer

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About the Reviewer
Stats: Age: 33 • Height: 5'11” • Inseam: 33" • Weight: 155lb • Industry affiliations / sponsors: None
Twenty years deep into a mountain biking addiction that began as a way to escape the suburban sprawl of Connecticut, Mike Kazimer is most at home deep the woods, carving his way down steep, technical trails. The decade he spent as a bike mechanic helped create a solid technical background to draw from when reviewing products, and his current location in the Pacific Northwest allows for easy access to the wettest, muddiest conditions imaginable.

Posted In:
Reviews and Tech Reviews Trail Bikes Trek Trek Fuel Ex