The Trek Fuel EXe is a mid-powered electric mountain bike that ticks a whole load of boxes, not least weight, geometry and handling

Product Overview

Overall rating:

Score 8

Trek Fuel EXe 9.9 XX1 AXS


  • Great geometry and sizing, handling blurs the line between enduro and trail riding, TQ motor is easily the quietest to date.


  • Shock tune is a little too firm in compression, BITS tool rattles in the steerer tube, would benefit from a front tyre with a more pronounced edge.


Trek Fuel EXe 9.9 XX1 AXS review


Price as reviewed:


Say hello to the brand new Trek Fuel EXe, a mid-powered electric mountain bike with some very interesting features, not least the TQ motor which is compact and quiet. With 29er wheels, 150mm front suspension and 140mm rear, could this be the bike that convinces analogue riders to switch it up? In this test we try to answer that question, and compare the Fuel EXe against three of its most exciting peers (see below).

Trek Fuel EXe need to know: 

  • Brand new Trek Fuel EXe is a 19.28kg (42.51lb) mid-power ebike
  • Germany made TQ motor is compact, quiet and delivers 50Nm torque
  • All models are powered by the same 360Wh removable battery
  • Frame travel gets bumped up to 140mm, combined with 150mm forks
  • Available in six models, starting with the Fuel EXe 9.5 at £5,750
  • AirWiz comes on both 9.9 models

The Trek Fuel EXe was the first of a new breed of e-bikes to come equipped with the TQ HPR 50 motor. And while the German made motor doesn’t boast the most torque (50Nm), or the highest peak power (300W) in our lightweight, mid-power e-bike test, it is extremely compact and extremely quiet. So small and so quiet in fact, that the Trek Fuel EXe regularly passes for an analogue bike.

Trek Fuel Exe 9.9 XX1 AXS

The concentric, ‘harmonic’ drive used by the TQ motor makes it one of the most compact and discreet designs on the market. It does get very hot though, which could be an issue if you live somewhere more exotic than the UK.

Frame, motor and battery

Part of the deception is down to the sleek full carbon frame, which, to the untrained eye, makes the EXe look much like any other Trek trail bike – the monochrome display embedded in the top tube the only real giveaway. The EXe is also an absolute doppelgänger for the new analogue Fuel EX, which just reinforces the illusion. 

Trek Fuel Exe 9.9 XX1 AXS

Mino flip chip gives geo adjust and makes it easier to go mullet.

Both 29ers deliver 140mm of rear wheel travel that’s bolstered up front by a 150mm fork. Flip the EXe over however, remove a couple of hex bolts, pop the protective cover off and you can slide the 360Wh battery effortlessly out of the bottom of the down tube. It’s the rabbit in the EXe’s hat. The battery weighs 1,834g and combined with the 1,850g motor, TQ has delivered a lightweight system. 

Trek Fuel Exe 9.9 XX1 AXS

The pyramid of lines at the base of the shock indicate it gets RockShox’s hydraulic bottom out control.

Having a removable battery has pros and cons. On the plus side, it can be removed for ease of charging or simply swapped out for a second battery, instantly doubling the range of the bike, rather than adding 50% like most range extenders. The only negative is that frame weights are typically a couple of 100g heavier than if the battery is fully integrated. 

Trek Fuel Exe 9.9 XX1 AXS

Monochrome integrated display is clear to read and gives all the essential info.

There’s also an aftermarket 160Wh range extender that slots into the bottle cage. And with the charging port that doubles as the connection for the range extender, directly above the bottle cage, Trek guarantees a short, secure coupling, even if the placement isn’t as good as on the Specialized Levo SL for weight distribution.

Trek Fuel Exe 9.9 XX1 AXS

Inside the steerer tube is a handy pull-out multi-tool. Bontrager’s one-piece bar/stem system is excessively wide at 820mm, so cutting down is recommended.

At 19.11kg with a headset tool, bottle cage, handlebar cut down and our Maxxis control tyres fitted, the Trek Fuel EXe is the heaviest in test. It’s also the one that rides the most like an enduro bike though so we can forgive that. Also, if you want the lightest bike in the EXe range, that honour goes to the 9.9 XTR which weighs almost 1kg less and costs £1,250, thanks to the Shimano XTR drivetrain and lighter Bontrager dropper post. And if it were available, that’s the bike we’d have preferred in this test.

Trek Fuel Exe 9.9 XX1 AXS

The Fuel EXe gets the latest RockShox Lyrik fork with Buttercups vibration dampers.


One of the main advantages of having such a compact motor, is that brands don’t have to work their suspension design around it. And that’s even more important with a single pivot design like on the Trek. With 140mm travel and 100% anti-squat Trek has the numbers on the EXe really dialled in. Unfortunately, we can’t say the same of the tune on the RockShox Super Deluxe shock. From day one it felt slightly overdamped in compression. Not so much as to make the bike feel harsh, it just increased the dynamic ride high and made the EXe feel harder to get off the ground even when running all of the damping adjusters wide open.  

Trek Fuel Exe 9.9 XX1 AXS

Airwiz syncs to your phone for checking pressures in both the fork and shock, but it’s more of a gimmick than a useful feature.

We had no such complaints with the 150mm travel RockShox Lyrik Ultimate fork. We are not sold on AirWiz though. The offset valve on the fork makes it harder to attach the pump and do you really need lights on your fork or shock to let you know if the pressure has changed? Hardly. That said, if RockShox can integrate ShockWiz into AirWiz, we think it would be well worth paying a premium for. 

Trek Fuel Exe 9.9 XX1 AXS

Ironically, the AXS wireless derailleur is hardwired to the TQ’s battery, but at least it’s one less battery to charge (the Trek has 8 batteries!).


One-piece carbon bar/stem combos get a bad rap, and rightly so, as most have a goofy profile that you can’t adjust out. Not the Bontrager Race Shop Limited unit on the Fuel EXe. Trek has absolutely nailed the profile, so for once, there really is no need to adjust anything. Weighing a scant 270g with a whopping 820mm width (830mm with grips), we chopped the bar down to 770mm after the very first ride. And what a difference it made. It eliminated the slightly weird flex when fully loaded and made the bike feel altogether more manageable.

Trek Fuel Exe 9.9 XX1 AXS

TQ’s controller is neat and compact.

In keeping with the oversized theme, the SRAM Code RSC four-piston brake callipers are paired with 200mm rotors front and rear, so stopping power has not been compromised just to shed a few grams. They are the thicker HS2 rotors too, so the lever feel is really positive and they dissipate heat better to give more consistent stopping power. Useful on a 19kg bike that can be ridden so hard. 

At one point we noticed the bite-point on the rear brake wander a little. It turned out that the rear axle just wasn’t cinched up fully – so the slight movement of hub was causing the rotor to reset the pistons. Rear axles working loose is a common problem on e-bikes, and once torqued up correctly the rear brake felt spot on. 

Trek Fuel Exe 9.9 XX1 AXS

Rear axle came loose during testing, but once cinched up, the four-piston Code brakes and 200mm HS2 rotors provided ample stopping power.

The loose rear axle probably happened when we swapped the stock Bontrager SE5 tyres for our Maxxis control tyres. Now, the Bontrager tyres were okay, back in summer when Trek launched the bike, but even then the pinging side knobs were a harbinger of poor wet weather performance to come. As such, the tyres on the Fuel EXe need upgrading. And, yes, we know how absurd upgrade sounds on a bike costing almost £14k.

So let’s balance things out with some suggested downgrades. We’d ditch some of the superfluous electronics, like TyreWiz and AirWiz. They add nothing in terms of  performance, only price, and by the time you get your phone out, connect to the SRAM app to sync with the correct parts, you could have checked your tyres with a regular pressure gauge and been off.

Trek Fuel Exe 9.9 XX1 AXS

The chunky Fuel EXe is built to be hammered.


The Trek Fuel EXe has the most progressive geometry in test. And with a superbly damped feel to the full carbon frame it can be ridden harder than any other bike here. But what Trek’s frame tech and geometry gain in raw speed, the overly damped shock seems to take away some of the playfulness that should be inherent in any trail bike. 

Trek Fuel Exe 9.9 XX1 AXS

An over-damped shock took the edge off the Fuel EXe’s playfulness.

On or off the gas, the EXe offers a near silent ride, and while the TQ motor has zero overrun, pick-up is almost instantaneous, so the motor has a really natural feel when pedalling. Now, if you want to pick your way up unnaturally steep, techy climbs, that’s going to be harder without the overrun. So if that’s the type of riding you’re into, we suggest getting a full power e-bike like the Trek Rail

Trek Fuel Exe 9.9 XX1 AXS

It was still a blast to ride, but a different shock tune could really help the Trek come alive.

With more torque but lower peak power than the Specialized Levo SL, the Trek Fuel EXe feels remarkably similar in terms of assistance, something that’s evident from the calories/metre elevation metric in our range test. That said, the Trek pulls away from the Specialized on steeper climbs, even if the range is nothing like as good as on Levo SL or Pivot Shuttle SL.

Trek Fuel Exe 9.9 XX1 AXS

There’s a lot to like about TQ’s system, but a range extender would be a good purchase to really broaden the Fuel EXe’s horizons.

E-bike comparison chart

For our power-hour challenge, we put all four bikes in max power mode, be that boost, Rocket, level 3 or Nitro. We then rode the same test loop where the bikes were fitted with the same tyres, ridden in the same conditions, by the same rider. The results were surprisingly different though. The loop consisted of one steep technical climb, two fireroad climbs and a few Tarmac climbs, depending on the bike. We recorded time and elevation to limp mode, typically 10% battery life, then rode until the lights went out. 

Pivot Shuttle SL V Levo SL V Forestal V Trek Fuel EXe range

Pivot Shuttle SL V Levo SL V Forestal V Trek Fuel EXe range comparison

Probably the most telling metric of all is the number of trails ridden. On the Pivot shuttle SL we completed 7 descents, which is almost doubt that of the Forestal. We also used the estimated calorie burn as a proxy for effort, where the calories burned per metre for elevation gives a good indication of rider input on each bike. The Specialized Levo SL required the most rider input, the Forestal Cyon the least.


Before the era of electronics in mountain biking, Keith Bontrager famously said; “strong, light, cheap: pick two.” Well, it looks like Trek has conveniently provided the exception to his rule. Not only is the Fuel EXe 9.9 XTR cheaper than the wireless SRAM XX1 AXS bike tested here, it’s every bit as strong and almost one kilo lighter. So that’s the bike to get, budget permitting. The EXe would then be the second lightest bike in test, not the heaviest, and the money saved would cover new tyres, a better shock tune and even a second battery.


Frame:OCLV Mountain Carbon, 140mm travel (138mm measured)
Shock:RockShox Super Deluxe Ultimate AirWiz RCT2 205x60mm
Fork:RockShox Lyrik Ultimate AirWiz Charger 3 RC2, 150mm travel
Motor:TQ 50Nm
Battery:TQ 360Wh removable
Display:TQ OLED Integrated w/controller
Wheels:Bontrager Line Pro 30 Carbon, Bontrager SE5 Team Issue 29 x 2.5in tyres
Drivetrain:e*13 e*spec Race carbon 32t, 165mm chainset, SRAM XX1 AXS derailleur and shifter, SRAM Eagle XG-1299 10-52t cassette
Brakes:SRAM Code RSC, 200/200mm rotors
Components:Bontrager RSL one-piece bar/stem - 820/45mm, RockShox Reverb AXS 170mm post, Bontrager Arvada 138mm saddle
Sizes:S, M, L, XL
Weight:19.11kg (42.13lb)
Size ridden:L
Rider height:5ft 11in (180cm)
Head angle:64.6º
Seat angle:70.3º
Effective seat angle:77.5º @740mm
Bottom bracket height:332mm
Front centre:811mm
Seat tube:440mm
Top tube:610mm