Trek’s Fuel EXe Is the Best e-Mountain Bike of 2023 (2024)

Weight: 40.9 lbs. (medium, 9.9 XX1 AXS // Price: $14,000 (9.9 XX1 AXS)

I did bad things on Trek’s Fuel EXe. But in my defense, I don’t care. Most of the trails where I live are, stupidly, closed to e-bikes. But I rode the EXe where I wasn’t allowed, and I had a metric sh*t-ton of fun.

Some of the fun came from being naughty, sure. A feeling that took me way back to the mid-1980s when I started riding mountain bikes. Back then, almost all trails were closed to mountain bikes. But my friends and I didn’t care. We just rode our bikes, explored, and grew our skills, asking for neither permission nor forgiveness. Because we were having fun and knew we weren’t hurting anyone or anything.

This review is of a bike, Trek’s Fuel EXe, not an essay about e-bike trail politics. Unfortunately, it is still difficult to separate the two. But I don’t find today’s debates about e-bike trail access to be substantively different than the debates we engaged in 40 years ago about mountain bike trail access.

I just wanted to say I don’t feel guilty about wanting to ride an e-bike or enjoying myself on an e-bike, and neither should you. Riding e-bikes is a blast; they are not the devil many cast them to be. And frankly, as e-bikes get quieter, sleeker, and less obvious (like this EXe), it will be increasingly difficult to tell them apart from unpowered bikes. And as they get better and lighter, also like this EXe, they’re going to become more appealing to more riders. Even ones who, in the past, had rejected e-bikes.

Guess what happened when I rode the EXe? Nothing. Nobody noticed, nobody said anything, and no horsem*n of the apocalypse appeared. I, however, enjoyed myself immensely because, with assistance or not, the EXe is a damn fine mountain bike. And when you add its sleekly integrated and well-tuned motor, the EXe becomes one of the most compelling bikes in recent memory.

While the usual e-bike story is about more power, battery, and range, the EXe falls into the intriguing e-light category where the story is less. The EXe is much lighter—by ten or so pounds—than a full-power e-bike because it uses a less powerful motor. A less powerful motor is a smaller motor that weighs less and requires a smaller (lighter) battery. While many will view less as less, I found that less powerful doesn’t mean less enjoyment. The EXe is proof that the old Less-Is-More axiom works for e-bikes too.

The EXe’s embrace of less makes it an appealing choice for e-curious riders who also want the feel and handling of an unpowered e-bike. It also attracts smaller and lighter riders put off by the wrestling match that can be riding a 50-pound e-mountain bike. Plus, the lower weight means it’s easier to load on a rack, carry up flights of stairs, or hang on the wall. These are chores that make life with heavier, full-power e-bikes burdensome.

Both the chassis and the motor represent new directions for Trek. While it retains Trek’s familiar suspension system, it’s an all-new and very different-looking frame from the crew in Wisconsin. And for the motor, Trek turned to a new-to-them supplier, TQ Group.

“We all wanted an e-bike that rode more like an acoustic bike,” said David Knauf, Trek’s full suspension product manager, “Like everything in the bike world, it generally comes back down to weight. Weight adds up and affects the ride of the bike significantly.”

Knauf states that Trek and TQ co-developed the HPR50 motor, which is essentially a less powerful, smaller, and lighter rendition version of TQ’s powerful (120Nm of torque) HPR 120S. “TQ had this HPR 120, which was huge. Knowing what their capabilities were to basically shrink that down as far as we wanted, we started out qualitative testing and playing around with different outputs of that motor [to] understand what was best for this mid-assistance category.” After considerable testing, Knauf noted that Trek and TQ found that 50 newton meters of torque provided the most balanced experience. “The goal the entire time was to find the bike that gave you enough assistance on the trail but didn’t compromise too much of what we appreciated in an acoustic bike,” he added.

Though not as big a name in e-bike motors as Shimano, Bosch, and a few others, TQ is no newbie startup: Its e-bike journey began in 2008. And, like many of its e-bike motor competitors, it is part of a large and diversified company. In addition to its e-mobility products, TQ plays in the robotics, automation, electronics, aviation, and medical fields.

Those resources allowed TQ to design an e-bike motor architecture it calls Harmonic Pin Ring, based on a principle called strain wave gearing. What’s interesting here is not the electric motor—it is a little different than any other e-bike’s electric motor—but its reduction gearing system.

All mid-drive e-bike motors need to slow the high RPMs of the electric motor to turn the chainring at a typical rider’s cadence: Usually about 60 to 100 RPM. Other mid-motors use a series of gears or a belt as a reduction system which lengthens the motor’s profile. The strain wave design, in contrast, employs a nested layout and achieves higher reduction ratios with fewer parts and almost no backlash (“play”). And lest you think this is some unproven or unreliable system, the moon buggy used by Apollo astronauts employed electric motors and strain wave gearing.

TQ’s final product looks more like an oversized BB standard than the typical e-bike motor. It’s also light, coming in at 1,830 grams: 120 grams lighter than the Specialized SL 1.1 system found in the first-generation Levo SL.

The HPR50 maxes out at 50Nm torque (300 watts maximum assist), putting the Fuel EXe into the growing e-light category of mountain bikes with the Levo SL and a handful of others. With less than half the maximum torque of a full-power e-bike motor, these e-light bikes don’t have the sheer thrust of a full-power e-MTB. But less powerful systems are smaller and lighter. They also draw less juice, meaning bikes can use smaller and lighter batteries. And that’s why this EXe is easily 10 pounds lighter than a comparable full-power e-bike. For example, the full-power Trek Rail weighs 51.3lb, while the similarly equipped EXe weighs 40.9 pounds.

Wrapped around the new motor is a mid-travel trail bike frame with 140mm rear travel. All complete bike models get a 150mm fork, though the frames are rated to take up to 160mm forks. Trek’s ABP (Active Braking Pivot) rear suspension is a single-pivot system with a floating brake arm. ABP allows Trek’s enginerds to fine-tune the bike’s anti-squat (pedaling) and anti-rise (braking) characteristics more than they could by using a more traditional single-pivot design. The frame fits a water bottle inside the main triangle, has a cargo mount under the downtube, and it’s compatible with air and coil spring shocks. There’s nothing radical in the bike’s fit or handling numbers. It’s a modern trail bike: long, reasonably slack in the head angle, with a steep-ish seat tube angle. Additionally, a flip chip gives riders two settings, though the difference is minimal to nearly the point of why bother.

While there’s a lot to gawk at and geek out about, the EXe still manages to blow away expectations once you get it on the trail. I got comfortable with it very quickly, and it wasn’t long before I was in love with this bike. I’m going to declare that this is one of the best mountain bikes—powered or unpowered—that I’ve ever ridden.

Everything about this bike makes it great, but I’ll start with the frame. The chassis has a modern fit and balanced handling that lets the rider climb comfortably or let it run on the descents. Yet the bike is still agreeable on mid-speed and flatter trails. There’s nothing particularly unique or different about the EXe’s geometry numbers, which is the point: It finds an equilibrium that works well on many kinds of climbs and flavors of descents without neglecting that some trails are flatter.

Sixteen years from its debut, Trek’s ABP suspension design continues to serve the brand’s bikes admirably. Though essentially a “simple” single pivot design, the EXe’s suspension is balanced against a mountain bike’s dynamic demands. Even with the assist, pedaling efficiency still matters. And the EXe does well in this regard, keeping the rider supported and the bike calm while floating up big climbs without sacrificing traction.

The suspension’s performance on the descents is similar: Good support and control while offering traction and smoothness. The feel from the RockShox Super Deluxe Ultimate shock feels particularly buttery; the RockShox Lyrik fork on the front does ride slightly firm—but that isn’t a bad thing on an e-bike.

Altogether the EXe’s overall feel on the trail is snappy and lively—two words rarely used to describe e-mountain bikes—enough that I often forgot that I was on an e-bike.

The motor’s lack of noise and smoothness is another reason I’d sometimes forget I was on an e-bike. I couldn’t hear it over my breathing on climbs; it’s so smooth that there are almost no vibrations or buzzing to feel in the frame. Plus, it is entirely free of clunking and lash. The EXe’s TQ unit is the most natural-feeling e-bike motor I’ve ridden to date. It doles out power in an approximately human way and so quickly that there’s almost no lag between when you start and stop pedaling; the motor power flows in and out. Legitimately, it just feels like you’re having a great day when pedaling this bike. I felt less surging and pushing from this motor, even in the highest assist mode, than I’ve experienced from any other e-bike motor.

The TQ feels exceptionally well-tuned, and the experience is refined, eclipsing even Specialized’s excellent motors. Some of this smoothness likely results from the TQ’s lower torque. The quiet system tricks the brain into perceiving the lack of noise as smoother. But riding the EXe was such a pleasant experience that I never missed the extra boost of a “full power” e-bike.

According to Trek, they spent a lot of time analyzing and quantifying e-bike motor noise. And while I don’t consider any of the current mid-drive e-bike motors loud, they all make noticeable (and not particularly pleasant) noise. Trek claims that, when measured in an anechoic chamber, its motor’s tonality, across a range of cadence speeds, is four to five times lower than competitors’ e-bikes, registering as “barely perceivable.”

After riding the EXe, I concur barely perceivable is a suitable way to describe the motor’s noise. It’s so quiet that it barely registers above (usually masked by) tire noise and breathing. Not only is it hushed, but the noise you can hear is a much lower pitch—almost like a cat’s happy purr—than the high-pitched whine of most e-bike motors.

So quiet is the HPR50 motor that I rode the EXe in a group, and other riders didn’t even know I was on an e-bike until they got a close look at the bike from the non-drive side or happened to see the discrete handlebar remote. To make it even stealthier, I covered the top tube display with electrical tape to hide it and covered the top tube logo with stickers. And I rode trails where e-bikes are barred. Of course, I can’t suggest you do the same, but no one I rode past gave me or the bike a second look.

The EXe’s 360Wh internal battery is good for “two to five hours,” according to Trek. While frustratingly vague, it’s also about as truthfully accurate as a brand can convey since so many factors influence battery range: air temperature, rider weight, terrain, and assist mode are examples. Weighing about 180 pounds, I rode for two hours and 40 minutes in the “Mid” assist mode and covered 25 miles with almost 2500 feet of climbing. I finished with under 30 percent battery remaining, so the two-to-five-hour estimate is accurate.

If you want more range or less range anxiety, the EXe offers a couple of options. One is a 160Wh piggyback battery ($660, 900 grams claimed weight) that fits into the bottle cage. You’ll lose that spot to carry a water bottle but gain 40 percent more range. One clever thing about this range extender, when hooked up to the bike, is that you can charge it and the bike’s in-frame battery concurrently.

The other option is to buy a second in-frame battery ($750). You can easily hot-swap the in-frame on the trail; if you’re willing to carry a spare 1,835g battery in your riding pack. Trek’s claimed charge time for the 360Wh battery is a relatively short two hours, while the 160Wh piggyback charges in an hour.

The EXe has a bright and easy-to-read two-inch OLED display flush-mounted in the top tube. It offers four data lines and a single button that powers the system on and off and loops through the data pages. A battery graphic and selected assist mode always show on top, with the bottom switching through different data pages with a button press. I appreciated that TQ offers multiple ways of conveying battery information—remaining battery charge as a percentage, estimated ride time, and range in miles. This system allows riders to confront their range anxiety in a way that suits them best. Other data pages show rider and bike power and speed. Overall, the TQ system’s display and controls are a model of simplicity. But if you like lots of metrics in front of you, the TQ system broadcasts information on an ANT+ channel, allowing you to pair it with a compatible GPS cycling computer. Riders may access further information and settings—and fine-tune the assist modes—through the Trek Central app for iOS and Android.

Everything added up, this e-lite mountain bike might provide a superior experience for many riders, even committed e-bike riders. Yeah, it’s not going to hurl you up the climbs the way a full-power e-bike will. Yes, I did wish for more range at times—if only because riding the EXe is so damn fun. But the Fuel EXe has enough power and battery capacity to offer substantial assistance, yet the bike remains lithe and agile. And it doesn’t punish the upper body on descents.

Based on Strava, even with the EXe’s assist, I was still slower on the climbs and descents than my town’s fastest pro rider on their acoustic bikes. I wasn’t even as fast as my best unassisted times from when I was in my best riding shape. But I could ride it quicker with less effort than I can at my current weight and fitness on an unassisted bike. It lessened—but did not eliminate—the pain and, most importantly, increased the fun in a quiet, sleek, and easy-to-ride package. These are the hallmarks of an extraordinary bike.

The EXe provides an e-bike experience that doesn’t overwhelm the mountain bike experience. Transitioning from a mountain bike to a full-power e-bike can be jarring. Full-power e-bikes are a lot: A lot of power and a lot of weight. Many riders adapt and are completely happy on full-power e-bikes, but if you’ve tried a full-power e-bike and found it just too much, the EXe will be a revelation.