The Trek Fuel EXe 9.9 XX1 AXS – In our big “Best Light-eMTB of 2023” group test

The Trek Fuel EXe 9.9 XX1 AXS is the forerunner of a whole new generation of Light-eMTBsl and was the first bike to come equipped with the new TQ HPR 50 motor. But does it have an advantage over the competition as a pioneer and an exclusive development?

At first glance, the Trek Fuel EXe 9.9 XX1 AXS is hardly recognisable as an eMTB. Generating 150/140 mm of travel at the front and rear, not only does it share the same hard numbers as its analogue brother, the Fuel EX, but also looks uncannily similar. It comes as no surprise that Trek’s € 14,499 Light-eMTB was the first bike on the market to feature the new TQ HPR 50 motor, because this was developed in close co-operation with Trek and covered by a three-month exclusivity agreement. Although this has now expired, the Trek stands out from the crowd of TQ bikes. The integrated display in the top tube relies on its own user interface, which differs from the standard TQ version and is more intuitive to use – and also provides more information! Moreover, the 18.9 kg Fuel EXe 9.9 XX1 AXS can be connected to the Trek Central app to recall helpful data such as the tire pressure and air pressure in the fork and shock, which are collected and sent to the interface by TyreWiz and AirWiz sensors.

For an overview of the test fleet head to the group test: The best Light-E-MTB 2023 – 8 bikes in review

The Light-eMTB Trek Fuel EXe 9.9 XX1 AXS 2023 in detail

The TQ HPR 50 motor draws its power from a matching 360 Wh TQ HPR Battery, which can be easily removed from the bottom of the frame and charged both on and off the bike. Moreover, an optional 160 Wh range extender allows you to expand the battery capacity, making the Trek an excellent companion even for longer tours – awesome! The frame features a tool mount on the top tube and there’s a minitool hidden inside the headset. Unfortunately, the locking system of the tool kit is rather loose, joining in with the rear brake line inside the frame for a loud rattle fest – annoying!

The Light-eMTB spec of the Trek Fuel EXe 9.9 XX1 AXS 2023

The Trek Fuel EXe 9.9 XX1 AXS comes equipped with RockShox suspension consisting of a Lyrik Ultimate Charger 3 fork and matching Super Deluxe Ultimate air shock with hydraulic bottom-out control. The American component giant also supplies the wireless 170 mm RockShox Reverb AXS dropper post. SRAM CODE RSC brakes with 200 mm rotors front and rear do stopping duties, while shifting is taken care of by an electronic SRAM XX1 AXS drivetrain, albeit not an entirely wireless one: the rear derailleur of the Fuel Exe is wired straight into the main battery. As a result, there’s a wireless remote on the handlebars but still a small cable running from the rear derailleur into the frame. But don’t worry, the system still guarantees up to 300 gear shifts even once the main battery is fully drained – unless the motor software reports an error or the bike is turned off! For the rest of the spec, Trek rely almost entirely on their in-house components, including the one-piece, 820 mm Bontrager handlebar/stem unit, which unfortunately doesn’t allow for fine-tuning except for the stem height, which can be changed using spacers. Bontrager also supplies the Line Pro 30 carbon wheelset and SE5 Team Issue tires. While the latter might be a good choice for moderate trail riding, the thin casing is too flimsy for rough trails, which can be a major issue, particularly in combination with expensive carbon rims. We recommend upgrading to more robust tires with tougher casings to protect the rims, especially if you’re likely to get rowdy.

Tuning tips: Shorten the handlebars | Shredders should upgrade to more robust tires

The geometry of the Light-eMTB Trek Fuel EXe 9.9 XX1 AXS 2023

The Fuel EXe 9.9 XX1 AXS is available in four sizes, S to XL. Our size L bike combines 483 mm reach and a 435 mm seat tube.The latter is one of the shortest in the entire test field, which together with the long-travel dropper post that can be fully inserted into the frame, ensures plenty of room for movement on the bike. A flip chip in the rocker arm lets you switch between a high and low setting, adjusting the seat angle between 77.3° and 76.8°, and the head angle between 65.3° and 64.8°. Flipping the chip alters the reach and stack slightly. We rode the bike mainly in the low setting.

Size	S	M	L	XL
Seat tube	380 mm	410 mm	435 mm	470 mm
Top tube	573 mm	600 mm	630 mm	658 mm
Steuerrohr	100 mm	110 mm	110 mm	120 mm
Head angle	64.8°	64.8°	64.8°	64.8°
Sitzwinkel	76.8°	76.8°	76.8°	76.8°
Chainstay	440 mm	440 mm	440 mm	440 mm
BB Drop	39 mm	39 mm	39 mm	39 mm
Wheelbase	1.188 mm	1.217 mm	1.247 mm	1.270 mm
Reach	428 mm	483 mm	483 mm	508 mm
Stack	620 mm	629 mm	629 mm	638 mm

The Light-eMTB Trek Fuel EXe 9.9 XX1 AXS 2023 on the trail

The Trek Fuel EXe 9.9 XX1 AXS puts you in a relaxed pedalling position that is perfectly suitable for long rides. The suspension is firm yet comfortable, but the wide handlebars position you quite far over the front. The TQ motor engages and disengages discreetly – more than once we had to check whether it was even turned on! The background noise is limited to a faint hum, which makes the TQ the quietest motor in the entire test field. However, the TQ HPR 50 reveals its dark side on steep, technical climbs, where it proved the weakest drive system in the entire test field – but then the Trek doesn’t feel at home on this type of terrain anyway. When negotiating steep technical sections, you have to actively weight the front wheel to prevent it from lifting. At the same time, however, you have to try to avoid unweighting the rear wheel to prevent it from spinning out of control. This isn’t at all easy and, as a result, the Trek is one of the worst climbers in this test alongside the Haibike.

The Trek is a true master of connectivity, allowing you to call up all crucial bike data using the Trek Central app.

When you start shredding your back down into the valley, you’re nicely integrated with the bike. Handling is intuitive and the weight is evenly distributed between the front and rear. Even in flat corners, the front wheel remains planted on the ground, so you don’t have to shift your weight forward to keep it tracking. While the Fuel EXe is potentially a mean carving machine, in tight sections, the wide handlebars deter you from slicing through corners at mach10. In our opinion, most riders would be better off using narrower handlebars. The front is stiff, providing ample feedback from the ground. While this isn’t such a big issue per se, it makes it rather hard to regain control over the bike when you get yourself into a pickle – and quite frankly, that happened to all of us at some point! As a result, the Trek lacks a smidge of composure, offering a similar ride feeling to the Pivot Shuttle SL with its super stiff suspension. Overall, the Fuel EXe follows the “jack of all trades, master of none” motto, working discreetly in the background without showing any real weaknesses, but without excelling at anything in particular either.

On the trail, the Trek Fuel EXe is easy and intuitive to ride, but the wide handlebars and stiff front end limit its agility and composure.

Conclusion

With the Fuel EXe 9.9 XX1 AXS, Trek have heralded a new generation of Light-eMTBs. It was the first bike on the market with the super quiet, natural TQ motor and relies on its own, intuitive user interface and modular battery concept. Uphill, you have to work hard to keep the front wheel tracking, but downhill, the Trek offers a balanced ride and intuitive handling, which makes it suitable for a wide range of applications. That being said, it’s not very forgiving when riding at the limit.

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You can find out more about at trekbikes.com

The test field

For an overview of the test fleet head to the group test: The best Light-E-MTB 2023 – 8 models in review

All bikes in test: Focus Jam² SL 9.9 2023 (Click for review) | Forestal Siryon Diode (Click for review) | Haibike LYKE CF SE (Click for review) | Orbea Rise M-LTD (Click for review) | Pivot Shuttle SL Pro X01(Click for review) | SCOTT Lumen eRIDE 900 SL (Click for review) | SIMPLON Rapcon Pmax TQ (Click for review) | Trek Fuel EXe 9.9 XX1 AXS

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Words: Simon Kohler Photos: Peter Walker, Mike Hunger