When the updated Fuel EX was launched the "standard" 27.5 wheel size was dropped, in its place were the 29" and 27.5" Plus bikes. For our conditions, the 29er is the pick of the bunch. The bike comes with 130mm front and rear suspension travel with a 67° head angle (lower setting), 433mm chainstays and several other clever design solutions.
To increase frame stiffness Trek decided to build the Fuel EX with a straight downtube toward the headtube. This resulted in less clearance for the fork crown and would lead to frames strikes when the bars rotate too far. To avoid frame damage, Trek created the Knock Block system which relies on a stop chip located on the top tube, which works with a keyed headset top cap that prevents the fork from turning too far. There is also a special keyed stem from Bontrager that helps ensure all of the parts remain lined up. The stem is only an aid and it's important to note that any other stem will work on the bike by installing a clamping headset spacer for you to install your favourite stem. The overall integration of the system is sleek.
On the underside of the downtube, Trek has placed Carbon Armor that protects the frame from debris and rock strikes. Cables are routed internally through their Control Freak internal routing. Although not as commonplace as it used to be, it was nice to see ISCG 05 tabs on the frame for those who would like to run a chain guide. I suspect it is a legacy from circa 2017 when some bikes still came with two-by drivetrains and needed a guide to avoid chain drop when things got rough.
The Mino Link system is Trek's version of a flip chip. This allows the rider to choose between a low and slack or lower and slacker geometry. In the lower setting, the head angle slackens from 67.7 to 67 degrees and drops the bottom bracket height by 10mm without negatively affecting suspension performance.
Trek's big ace is the RE:aktiv suspension technology that they developed in partnership with custom suspension tuner Penske Racing Shocks. In short, RE:aktiv was designed to improve a bike's pedalling performance without affecting its ability to absorb impacts. A spring-loaded valve inside the shock body allows for increased low-speed compression for pedalling support on smoother terrain, but when the shock shaft speed increases the valve opens up, enabling the shock to quickly and smoothly absorb the impact before the valve closes again.
Another neat piece of design is Trek's Active Braking Pivot (ABP). ABP uses a concentric pivot around the rear axle to separate the braking force from the suspension system allowing the back end to maintain better contact with the trail when braking.
- FrameOCLV Mountain Carbon main frame & seatstay, alloy chainstay, ABP, Boost148, Knock Block steerer stop, Full Floater, EVO link, tapered head tube, Mino Link, Control Freak internal routing, Carbon Armor, PF92, ISCG 05, G2 Geometry, 130 mm travel
- ForkFox Performance 34 Float, GRIP 3-position damper, tapered steerer, G2 Geometry w/51 mm offset, Boost110, 130 mm travel
- ShockFox Performance Float EVOL, RE:aktiv with Thru Shaft 3-position damper, tuned by Trek Suspension Lab, 210x52.5 mm
- WheelsBontrager Line Carbon 30, Tubeless Ready, 54T Rapid Drive, Boost110 front, Boost148 rear, tubeless strips included, valves sold separately
- TyresBontrager XR4 Team Issue, Tubeless Ready, Inner Strength sidewalls, 120tpi, aramid bead, 29x2.40˝
- ShiftersSRAM GX Eagle, 12 speed
- Rear derailleurSRAM GX Eagle, Roller Bearing Clutch
- CrankTruvativ Descendant 7k Eagle DUB, 32T Direct Mount
- Bottom bracketSRAM DUB Press Fit, 92 mm
- CassetteSRAM XG-1275 Eagle, 10-50, 12-speed
- ChainSRAM GX Eagle
- SaddleBontrager Arvada, austenite rails
- SeatpostBontrager Line, internal routing, 31.6 mm, 15.5: 100 mm, 17.5 & 18.5: 125 mm, 19.5 & 21.5: 150 mm
- HandlebarBontrager Line Pro, OCLV Carbon, 35 mm, 15 mm rise, 750 mm width
- GripsBontrager XR Trail Elite, alloy lock-on
- StemBontrager Line Pro, Knock Block, 35 mm clamp, 0-degree
- HeadsetKnock Block Integrated, sealed cartridge bearing, 1-1/8˝ top, 1.5˝ bottom
- BrakesetShimano SLX M7000 hydraulic disc
On the Trail
I'd best describe riding the Trek Fuel EX as feeling like "an old pair of jeans". By that I mean that riding the Fuel EX is familiar and neutral with no oddities to get used to. The Fox 34 Performance fork took a little longer than usual to dial in but once I got it balanced with the rear suspension, it handled duties up front quite well. Trek's suspension set up calculator was helpful during set up. It provides recommended pressure, sag, and rebound settings after you enter your weight and the bike model. I used the recommended settings as a base and then worked my way from there to get the bike to ride to my liking.
It's becoming a bit of a cliché to say that a bike both climbs and descends well but it does apply to the Fuel EX. The rear, with the RE:aktiv shock technology, can be ridden wide open under most circumstances. In fact, I never found the need to lock it out, only riding it firm for a short while for testing purposes. Depending on the base set up, you could opt for the Trail (middle setting) on faster, smooth trails to add some "pop" to your ride. The Fuel EX scampers up anything in its path with the rear offering bucket loads of traction. The Trek does require the rider to move forward on the saddle to negate the slacker seat tube angle. Thankfully, the front wheel stays planted making it easy to stick to your line.
During our limited time on the bike, it didn't feel like the lower Mino Link setting impacted efficiency on steep, technical climbs that much. It, however, adds a dose of fun to the bike on the downs. Half a degree in head angle doesn't sound like a lot, and with the lower bottom bracket thrown in, the bike does feel like it rails berms with more zest.
Having recently spent some time on an older generation 29" trail bike, I was grateful for the modern design and technology advances on the Fuel EX. There are no signs of it being lazy to turn or negotiate tight sections. The advent of 1 x drivetrains has allowed manufacturers to tuck the rear wheel in close to the bottom bracket and even though the Fuel EX can take a front derailleur, its short chainstays make for an agile and confident bike.
Trek's ABP rear suspension deserves a mention. It keeps the rear active no matter what. Yes. we shouldn't really be braking going through rough terrain, but it happens from time to time, and then an active rear suspension that keeps tracking and absorbing the terrain is a thing of beauty (and a crash saver).
The 35mm Bontrager bar and stem combination is the most comfortable that I have ridden. I tried the 35mm standard as an early adopter and I wasn't all that impressed as the handlebar felt too stiff in my hands. Although the Bontrager components did not suffer from the same issue, just keep in mind that 35mm mounts for accessories (lights, GoPro, HR monitors, etc) are still a bit scarce. I like the 750mm width of the handlebars although I feel that manufacturers should fit 780mm as standard and allow riders to trim the bars down to their desired width.
Bontrager XR4 Team Issue tyres were a pleasant surprise. They offered good traction and acceptable rolling resistance for a trail tyre. These tyres are certainly an option to look at if you are in the market for a good all-round trail / all mountain tyre for own bike.
Trek's Fuel EX is an incredibly versatile bike, even more so considering local trails and conditions. Light and fast enough to tackle the weekend's racing while capable enough to throw down the side of a mountain. It further solidifies the new bread of 120mm / 130mm 29ers trail and all mountain bikes as the go-to option for the perfect one bike.