2016 Trek Fuel EX 9 29

(discontinued)

Reviewed by AJ Barlas and Fred Robinson // Photos by Lear Miller

Trek's Fuel EX range of bikes are aimed at the honest trail rider - those looking for a quality, fun bike that can handle a good variety of trails, but not necessarily something for super rowdy terrain. We previously tested the Fuel EX 27.5, so it was fun to jump aboard the bigger wheeled brother and see how it compared.

For 2016, the Fuel EX 29 sees several changes for the better - it's slacker, offers adjustable geometry, has shorter chainstays thanks to the new Boost rear axle standard, and the rear shock has been updated to no longer feature Trek's DRCV. This was one of the only bikes in the 2016 Vital MTB Test Sessions with Boost spacing front and rear, but does it make a difference? Did the new RE:aktiv damper improve performance over a regular shock? Read on to find out.

Highlights

• Aluminum frame
• 29-inch wheels
• 120mm (4.7-inches) of rear wheel travel // 130mm (5.1-inches) fork travel
• Full Floater suspension with Active Braking Pivot (ABP)
• RE:aktiv shock damping technology
• Tapered headtube
• External brake routing, internal cable routing, internal seatpost routing
• Adjustable geometry via Mino Link flip chips
• PF92 bottom bracket with ISCG05 mounts
• Boost 110mm fork axle spacing
• Boost 148mm rear spacing with 12mm through axle
• Measured weight (size 19.5, no pedals): 28.6-pounds (13.0kg)
• MSRP $4,000 USD

The Fuel EX 9 29 comes with a handful of unique features, and is highlighted by the RE:aktiv damper technology. Trek worked with motorsports specialists Penske Racing Shocks and FOX to create a shock with regressive damping. In a race car application, regressive damping is designed to be firm when cornering but supple for sudden impacts. When applied to mountain bikes the goal is similar - to provide support when pedaling or pumping but open up when needed.

Most rider inputs create low shaft speeds, while bumps create higher shaft speeds. Inside the shock, the main piston is equipped with a special spring loaded valve. The faster the shaft speed, the more the valve opens up and the more oil is allowed to flow through. Trek says the valve is capable of delivering lots of low-speed compression damping, fluid high-speed compression damping, and an instant, seamless transition between the two. Because of this Trek says RE:aktiv achieves what inertia valves have been unsuccessfully attempting for years by balancing pedaling performance with big-hit absorption without feeling harsh. The way it’s able to react so rapidly is by changing the surface area that the oil is pushing against.

The shock's abilities are most apparent in the "Climb" or "Trail" compression settings as the bike remains quiet during pedaling, but still allows the suspension to move due to ground impacts. This translates to the rear wheel moving out of the way while the rider continues to put power down. How it functions is really quite amazing, but it has its limitations and we’ve found that there is a time and a place for its use, much like any of the regular pedal platform adjustments on all rear shocks.

The spring curve of FOX’s relatively new Float EVOL (extra volume) shock closely matches the linear curve Trek previously relied on DRCV to provide, so DRCV gets the boot this time around. The shock is still proprietary due to its odd 184x48mm (7.25x1.875-inch) dimensions and RE:aktiv damper, however. To get that 120mm of travel, Trek's Full Floater suspension design actuates the shock from both ends with a one piece magnesium EVO Link on top and a concentric pivot at the rear axle known as ABP.

Boost is the other unique-ish technology that higher end Fuel EX 29 models include. We say unique-ish only because it's not commonplace yet. Boost was originally aimed to create stiffer 29-inch wheels without having to throw down the extra coin for carbon hoops. This was achieved by moving both rear hub flanges 3mm out from the center, resulting in a new 148mm axle width. Wider spacing gives the spokes a greater bracing angle, which in turn generates a stiffer wheel. This slight change also provided better tire clearance, which means that they can run slightly shorter chainstays. The front wheel also includes Boost, which takes the hub width from 100mm up to 110mm for similar results.

Additional features include room for a water bottle inside the front triangle, a PF92 bottom bracket, ISCG05 tabs, close to 19mm (0.75-inches) of mud clearance with the stock tires, optional direct front derailleur mount, and a fork with a custom 51mm offset. Aside from the stealth dropper post and rear derailleur cable (which is held taught in the frame), routing is external on the Fuel EX 9 29, which makes for easy service with no rattle. You'll find a large downtube guard for stray rock protection, but consider adding some extra protection to the stays for chainslap.

Trek offers the Fuel EX 29 in four aluminum complete builds ranging from $1,990 to $4,000 USD, two carbon builds at $5,300 and $8,400, and as a carbon frame for $3,300. There's also the option to build a fully custom bike through Trek's Project One program. Fuel EX 8 29 and above benefit from Boost, while the Fuel EX 7 and 5 29 retain 2015’s frame with standard hub spacing. We tested the $4,000 aluminum Fuel EX 9 29, which has an extra 10mm of fork travel (130 vs 120mm) over the other models.

Geometry

2016 brings Trek's adjustable geometry feature to the Fuel EX 29 lineup via the Mino Link flip chips near the top of the seatstays. The geometry chart above shows numbers in the "low" setting with the option to steepen the head angle to 69.4-degrees and raise the bottom bracket by 8mm (0.3-inches). We measured our test bike bottom bracket height at 340mm (13.4-inches) in the low setting, so it's possible that the listed geometry is with a shorter travel 120mm travel fork. While slacker than the previous Fuel EX 29, at ~68.8-degrees this bike is a degree or so steeper than many other recent short travel 29ers. Thanks to Boost, Trek was able to drastically shorten the chainstays from 452mm to a much more nimble 436mm (17.2-inches), which is par for the course among comparable bikes. As you can see, it comes in several sizes to suit just about any rider.

On The Trail

Setup was a breeze thanks to Trek's suspension calculator, which provides a great starting point for air pressure and rebound. In the open "Descend" compression setting, we found the rear end to be more active during seated and standing pedaling efforts than similar bikes ridden during Test Sessions. Smooth climbs consisting of mellow to considerable grades with the occasional small rock feature saw the bike exhibit a good, nimble, and lively attitude. The bike is more enjoyable ascending than the Transition Smuggler thanks to a more energetic, positive demeanor. It’s more sporty than the static weight would suggest, and there were minimal issues with pedal strikes. Once the compression dial was set to the medium "Trail" setting, however, the beauty of the RE:aktiv damper really showed through.

In the medium compression setting the suspension was remarkably quiet as the RE:aktiv damper stepped in to allow for more power to the floor during climbs, but still provided plenty of traction on the dry, abrasive conditions of South Mountain's trails in Phoenix, Arizona. In this setting the bike required less energy to move up the hill. Climbing up rocky, stepped technical sections the bike had a great balance of control, moving through its travel smoothly while offering support, and notably missing harsh feedback that would result in it getting hung up on square edge features. It also helped with the bike's geometry, sitting a little higher in its travel, effectively resulting in a steeper dynamic seat tube angle.

Going to the firmest "Climb" mode was too much of an extreme when climbing rough sections, however, as it lost a lot of traction on relatively average grades with rough-ish patches. On smoother road climbs it was great to have it locked out, though, with minimal suspension movement while practicing good pedal technique.

Overall, we found the Trek Fuel EX 29 to be an above average climber. It's not a snappy XC style ascender, but is spirited enough and assists the rider rather than feeling like a dead sail. It is by no means a race bike out of corners or up moderate pitches, but does climb reasonably well with the stock 32-tooth chainring. If you're inclined, the bike will provide better antisquat traits with a smaller chainring.

Even with a swapped out 50mm stem, we felt as though the cockpit on the size 19.5 bike we tested was a little long while seated. The reach, on the other hand, was a little short - this is predominantly due to a slack 67-degree actual seat tube angle. On moderate to steep punches we found it a bit difficult to get up over the front end while in the saddle, and would wind up riding way up the nose of the seat in order to compensate. Moving the seat forward on the rails helped with this as well.

The 50mm replacement stem took place of the stock 70mm Bontrager Rhythm Comp. We should also mention that the Bontrager Race Lite 750mm (29.5-inch) wide bars were swapped out for something a tad wider. These changes created a more comfortable setup for how we prefer to ride. Even so, a steeper seat tube would result in it climbing more favorably, especially on steep technical grinds.

While descending smoother, lower grades with the compression lever set to Trail, the bike responded well to rider input and zipped along at a solid pace when exiting corners or putting a few pedal strokes in to get back up to pace. In this setting it tracked reasonably well in loose over hard conditions, though it was easier to break loose under aggressive cornering. High speed descents and g-outs often overwhelmed Trail mode during descents, however, so flipping dials is a must do to get the most out of the bike.

On the same type of trails with the compression wide open the bike was much more willing to being pushed hard into corners, garnering increased traction but losing some of the sporty attitude exhibited in the medium compression mode. This resulted in more required rider input and planning in order to pick up over obstacles and square edges.

Getting up to speed in rough terrain we noticed the suspension tracks well through all types of smaller hits. The bike comes out of deep compressions well and has a nice bottomless feel without feeling harsh. We never really felt the end of the travel despite using the full amount many times, even though there are no volume spacers in the shock from the factory.

During successive high speed hits it never packed up or felt like it was hanging up. However, the Fuel EX didn't exhibit the same level of confidence inspiring stability that we found with the Transition Smuggler or Evil Following, with the Fuel EX requiring an extra level of rider guidance in order to keep the bike on line. In fact, due to its tendency to wander we had a couple of "moments" in parts of the trail where the Transition and Evil would just motor along comfortably. In rough conditions the bike feels deceptively tall despite running some similar numbers to its competitors. The suspension didn’t give what we would describe as a planted ride, and due to its softer, more active, and lively nature it preferred to be ridden with more of a playful attitude. One potential way to boost the bike's overall stability in the rough would be to run a little more sag and add a volume spacer for a more progressive but deeper feel.

Here's the suspension in action:

Regarding the Boost wheels, after a few days of good hacking the rear wheel eventually lost some spoke tension, and any half decent hit or hard corner would result in horrible noises coming from the rear wheel flexing. As such, we were unable to truly discern any benefits to the wider system at that time. It should be noted though, that it's is fairly typical of a new wheelset to require some attention after initial break-in. Our second tester got to ride the bike after we had adjusted the spoke tension and felt the wheels went unnoticed, essentially performing as they should and feeling similar to that of a well trued, solid 650b wheelset. The frame was stout, too. In short, Boost works, but only when the wheels are properly tensioned.

Build Kit

Trek’s $4,000 Fuel EX 9 29 model is pretty competitively priced, though four grand can go a long ways with other "consumer direct" brands, especially when you consider the components. Even so, this bike comes ready to rally with solid FOX suspension front and rear, a SRAM Roam 30 wheelset, trustworthy Shimano XT brakes with dual 180mm rotors, a RockShox Reverb Stealth 125mm dropper, and a reliable SRAM X1 1x11 drivetrain.

The 130mm travel FOX Performance 34 Float fork provided a stable ride with minimal adjustments, and the suspension giant seems to have moved away from the issues that plagued them a couple seasons ago. The fork used its travel well while offering a good amount of support. It never felt overly active and was generally quieter than the rear of the bike.

For the terrain we were riding, we would swap out the stock 2.3-inch tubeless Bontrager XR3 Expert tires for something with a bit more meat. While the XR3 tires were okay, they didn’t inspire a great amount of confidence in loose over hard corners and their lightweight sidewalls added to the bike's instability in high speed chunder. That said, these were one of the only thinner sidewalled tires to not experience a puncture during Test Sessions, so that's a plus.

Aside from the rear wheel not having proper spoke tension when we first hopped on the bike, the SRAM Roam wheels were solid. After tightening up the spokes our second tester was able to get on without any of the annoying, sketchy sounding flex observed during the first tester's rides, and went on to note that the wheels felt inline with a sturdy set of 650b wheels as claimed. At the end of our test the rear wheel was only slightly out of true.

As mentioned above, we swapped out the somewhat narrow low-rise bars and longish stem for something that better suited the descents, but realize that these cockpit choices are a personal preference. The supplied grips were not the most comfortable either, with a very thin, hard rubber that felt pretty harsh on rough trails.

Long Term Durability

Outside of regular maintenance like tires, brake pads, and checking the spoke tension of the wheels, the Trek Fuel EX 9 29 appears ready to go the extra mile. Thanks to some clever cable routing we don’t foresee any issues from excessive rub, and given the rest of the decent quality components and good construction there is no reason to be concerned with the long term durability of the bike.

Towards the end of our last ride we did notice a creak developing in the pivot located just above the bottom bracket. Simply snugging up the hardware resolved the issue.

Trek backs the frame with a lifetime warranty, though there is a five year condition on the swing arm and one year on paint and decals.

What's The Bottom Line?

Trek’s Fuel EX 9 29 is a good value with some serious suspension technology that only adds to the fun times provided by a short travel 29er. You've got to be willing to flip some levers mid-ride to really see what it's capable of, so "set it and forget it" riders may not appreciate all the bike has to offer. The ride's conservative geometry works well on a range of terrain and features, and though the bike doesn’t really nail either the climbs or the descents, it’s a solid all-around steed. While very lively and active, it lacks a super confidence inspiring ride when things get truly wild. Some minor suspension tweaks and a burlier set of rubber could make it a more stable descender.

Visit www.trekbikes.com for more details.

Vital MTB Rating

• Climbing: 4 stars - Excellent
• Descending: 3 stars - Good
• Fun Factor: 3.5 stars - Very Good
• Value: 4 stars - Excellent
• Overall Impression: 4 stars - Excellent

Bonus Gallery: 23 photos of the 2016 Trek Fuel EX 9 29 up close and in action

About The Reviewers

Fred Robinson - Age: 31 // Years Riding MTB: 13 // Height: 6'1" (1.85m) // Weight: 240-pounds (108.9kg)

"Drop my heels and go." Fred has been on two wheels since he was two years old, is deceptively quick for a bigger guy, and likes steep, fast trails where he can hang it off the back of the bike. Several years of shop experience means he's not afraid to tinker. He's very particular when it comes to a bike's suspension performance and stiffness traits.

AJ Barlas - Age: 35 // Years Riding MTB: 15+ // Height: 6'3" (1.91m) // Weight: 165-pounds (74.8kg)

"Smooth and fluid." Hailing from Squamish, BC, AJ's preferred terrain is chunky, twisty trail with natural features. He's picky with equipment and has built a strong understanding of what works well and why by riding a large number of different parts and bikes. Observant, mechanically inclined, and always looking to learn more through new experiences and products.

Which reviewer resembles you the most? Don't miss our Q&A with the testers for more insight about their styles and preferences.

About Test Sessions

Four years ago Vital MTB set out to bring you the most honest, unbiased reviews you'll find anywhere. That tradition continues today as we ride 2016's most exciting trail, all-mountain, and enduro bikes in Phoenix, Arizona. Reviews can be accessed 24/7 in our Product Guide. Test Sessions was made possible with the help of Rage Cycles. Tester gear provided by Troy Lee Designs, Royal Racing, Smith, Fox Racing, Race Face, Easton, and Source.