TREK FUEL EX 9.9 XX1 REVIEW

THE LAB

Offered in sizes XS through XL, the new Fuel EX gets an extra 10mm of rear wheel travel, bringing it to 140mm, with a 150mm fork up front. The Fuel EX has features found on other Trek mountain bikes, like their Mino Link adjustable geometry, Trek’s Active Braking Pivot (ABP) suspension, and a full-length downtube protector. However, there are plenty of awesome new features that previous generation Fuel EX’s did not have. One of those features is the downtube storage solution, which is probably our favorite and most weather-resistant compartment we’ve seen yet. On the showroom floor, the Fuel EX is a 29er, but it has the ability to run a 27.5” rear wheel when combined with a 160mm front fork. It also has an integrated tool in the stem, size specific stays, an adjustable More/Less progressive suspension chip, and angle adjustable headset cups. The new adjustable headset cup system allows riders to adjust the headset a full degree steep or slacker, From 63.5 up to 65.5. That is huge!

The Fuel EX Gen 6 has a wide range of builds starting from $3,699.99 with two aluminum frame options, before getting into the carbon fiber frames from $4,699.99. The model we have for review, the Trek Fuel EX 9.9 XX1 AXS is the top of the line model, and comes with a price tag of $10,749.99.

With a price tag north of 10k the build better be tip top, and for the most part it is. Up front there’s a Kashima-coated 150mm travel Fox Factory 36 fork, which is paired to a Fox Factory Float X shock to control the 140mm rear travel. Driving and stopping power is delivered courtesy of an oil-slick SRAM Eagle XX1 AXS wireless groupset and SRAM Code RSC 4-piston brakes. These burly Code brakes stopping on the 203 front and 180mm rear rotors could likely be one of the bigger indicators of how capable the new Fuel EX is designed to be. In-house brand Bontrager supplies their top tier Line PRO 30 carbon wheels, which are wrapped in their SE5 tires.

The bar-stem combo is a brutally stiff Bontrager RSL unit, which features a neatly integrated multi-tool. The bar/stem combo weighs in at 250 grams, not including the weight of the multitool. The effective stem is 45mm in length and has a zero degree rise. The handlebar is supplied at a massive 820mm in width, has 27.5mm of rise, 7 degrees of back-sweep, and 6 degrees of up-sweep. Rounding out this build is the RockShox Reverb AXS seat post with 170mm of drop for sizes Large (reviewed) and XL.

The geometry of the Fuel EX was built around the need for a highly capable bike that felt at home in all terrain. The geometry is adjustable both by the Mino Link and the adjustable headset cups as mentioned above. For most of our review period the bike was ridden in the neutral headset setting (64.5°) with the Mino Link constantly being switched between both settings. In the neutral headset and low Mino Link setting, the Fuel EX has a 64.5-degree head angle; 77.2° effective seat tube angle and 38mm bottom bracket drop across the S-XL 29ers. The rear end is size-specific from 435mm to 450mm, with the size Large coming in at 440mm. The reach is 485mm, the stack is 621.3mm, and the wheelbase adds up to 1,250.2 mm on this size large test bike.

Something worth noting is that riders will see different numbers if they mount a 27.5” rear tire and increase fork travel to 160mm, which this bike is approved for. It’s crazy to think where the Trek Fuel EX was ten years ago, to now being a coil-sprung ready mullet with a 160mm fork and DH brakes! Evolution is real and we’re all for it.

Downhill oriented riders looking for an aggressive trail bike that they can put in big days on, or trail riders looking for a longer travel bike, will be very happy that Trek has ripped the Fuel EX’s envelope wide open. During our review period, the Fuel EX handled copious amounts of chatter and soaked up some fairly big hits, even on shuttle days chasing longer travel bikes. Right out of the gate the acceleration of this bike was quick. It doesn’t feel as sluggish as its bigger sibling, the Trek Slash, though this will likely not come as a surprise. The Fuel EX is the sportier of the two, yet the frame stiffness and body position at speed had us feeling like the Fuel EX wouldn’t be too far behind the Slash if it were a race to the bottom. While there’s no substitute for travel on truly rough terrain, the Fuel EX does well until you realize you’re at speed on terrain that would make a 160mm bike work. The downside to this is a slightly stiffer, or firmer suspension feel than previous generation Fuel EX’s. While we were very happy Trek has finally given an aggressive, progressive feel to the bike, there will no doubt be a lot more riders who will miss the in-the-saddle comfort and cushion of the older designs. With Trek’s adjustable suspension progression chip, you have the ability to give the bike more or less progression and tune the feel a bit, or opt for a coil shock if you’d like, but ultimately the fact remains, the new Fuel EX has a slightly more aggressive feel, for better or worse. It’s nowhere near VPP but closer to how a DW-Link bike feels when hitting square-edge hits at speed.