Trek Fuel EXe Aluminum
Wheel Size: 29’’ (compatible with 27.5’’ rear)
Travel: 140 mm rear / 150 mm front
Geometry Highlights:
- Sizes offered: S, M, L, XL
- Headtube angle: 64.8° (Low setting)
- Seat tube angle: 76.8° (Low setting)
- Reach: 483 mm (Size Large, low setting)
- Chainstay length: 440 mm (all sizes)
Material: Aluminum
Price:
- Complete bikes: $5,499 – $6,599
Intro
The Trek Fuel EXe isn’t new, but the aluminum version that Trek launched today is, bringing the wild TQ HPR50 drive system to a more affordable package — and adding some additional geometry adjustability while they’re at it.
The Frame
Most of the details of the Fuel EXe aluminum frame carry over from the carbon one — it’s got 140 mm of rear wheel travel paired with a 150mm-travel fork (in stock guise; Trek condones running up to a 160 mm one) and can optionally be run with a 27.5’’ rear wheel, with the geometry-adjusting flip chip in the high position (more on that below). Trek does note that doing so will throw the speed readings on the display off slightly, and reduce the maximum speed at which the motor provides assistance by about one kilometer per hour since the system is calibrated for a 29’’ wheel.
In contrast to the standard Fuel EX, there’s no second flip chip to toggle the shock progression, though the aluminum Fuel EXe does get the angle-adjusting headset cups from that bike (which the carbon Fuel EXe lacks). The Fuel EXe gets a UDH derailleur hanger for SRAM Transmission compatibility and features a 180 mm brake mount, which can be adapted up to 203 mm if you’d like to run a bigger rear rotor.
All four sizes leave room for a water bottle inside the front triangle (though only up to a 20 oz one on the Small frame), and get internal routing for all the cables. Trek doesn’t publish suspension kinematics but says that the Fuel EXe can be run with air or coil shocks (in a 205 x 60 mm trunnion mount) and that the Fox Float X and DHX, the RockShox Super Deluxe air, and all coil shocks from both brands are known to fit. Other shocks may also clear but haven’t been verified to work. The Fuel EXe forges the Knock Block headset that Trek has used on a lot of bikes over the years.
The Drive System
The big news with the original carbon Fuel EXe was the TQ HPR50 drive system, and that carries over unchanged to the aluminum version. It’s a compact, lightweight motor and drive system that offers 50 Nm of torque (as compared to 85 to 90 Nm in bigger, full-power eMTB drive systems) and up to 300 Watts of power. The stated weight of the drive unit is just 1,800 grams (about 1,100 grams lighter than a full-power Shimano EP8, for example). And while there are a number of lighter, lower-power drive systems on the market, what sets the HPR50 apart is its “Harmonic Pin Ring” reduction system.
In short, electric motors spin way too fast to match the cadence of a human pedaling a bike, so a lot of what goes into an e-bike drive unit is actually a series of gears and/or belts to slow down the final output to a usable range. In those packages, the motor itself is offset from the cranks, and the output shaft the cranks attach to sits forward of it, at the business end of the reduction system. The HPR50 works differently. The motor is concentric to the cranks, and the gear reduction happens in a single step.
The gist of the design is that, instead of having gears that mesh normally, the HPR50 has a pair of splined rings that mesh one inside the other, but with the inner ring having fewer teeth than the outer. The inner ring also pivots slightly eccentrically, so that rather than spinning with and driving the outer ring, it precesses around the outer ring slowly, moving one tooth over at a time, and thus providing a reduction in motor speed of 17:1.
That means that at a given pedaling cadence, the Fuel EXe’s motor is turning much more slowly than those in more conventional drive units — a gear reduction of more like 50:1 is common — which Trek says helps make for a quieter system and a more natural feel to the power delivery than you get with other e-MTB drives. It’s claimed to be both quieter and also a less irritating, whining sound than most drive systems, which they argue is at least as important as outright volume — citing the example of a mosquito buzzing as something that’s quiet, but still very annoying.
[Trek’s writeup on the sound analysis they’ve done for the TQ drive system is pretty interesting, but too involved to cover in full detail here. Check it out on their site if you’re interested.]
The main battery has a 360 Wh capacity, and an optional range extender (which fits into a water bottle cage, with an additional strap to keep it secure) adds an extra 160 Wh. The main battery is removable, though doing so requires removing the battery door and a couple of bolts to slide it out the end of the downtube, just forward of the motor. The main battery can be charged in the bike or when removed, and the range extender can be daisy-chained to charge both simultaneously. Charge time for the main battery is stated at 2 hours; the range extender is said to take about an hour. The range extender retails for $600, plus $50 for the power cable to connect it to the bike, and $10 for the mounting bits (sold separately because Trek’s TQ-equipped road bikes use different versions).
Fit & Geometry
The geometry of the aluminum Fuel EXe is identical to that of the carbon version (with the caveat that the aluminum frame adds the optional +/- 1 degree headset cups from the standard Fuel EX). It’s offered in four sizes, Small, Medium, Large, and XL, with all four getting a 64.8° headtube angle and 76.8° effective seat tube angle; reach ranges from 428 mm on the Small to 508 mm on the XL, with the Medium coming in at 453 mm and the Large at 483 mm. The chainstays are 440 mm long for all four sizes. Those numbers are all stated with the flip chip in the low position, and the stock zero-degree headset cups. The high flip chip setting steepens the angles by about a half degree, adds a few millimeters to the reach, and raises the bottom bracket by 7 mm, from 39 mm of drop to 32 mm.
Those numbers are also fairly similar, but not quite identical to the standard Fuel EX, which we found to be an especially well-rounded and versatile bike. Trek doesn’t publish a geometry chart for the Fuel EXe with a 27.5’’ rear wheel, or with the optional angle-adjusting headset cups, but their website does list those options for the standard Fuel EX, and you can get a pretty good idea of what the EXe would look like by extrapolating from those. It is also worth noting that the Fuel EXe comes in fewer sizes than the Fuel EX, which adds an XS, M/L, and XXL to the range.
The Builds
Trek is offering the Fuel EXe in three new builds on the new aluminum frame, to go with the existing carbon-framed options (see Trek’s site for the rundown on those).
- Drivetrain: Shimano Deore 12-speed w/ e*13 Plus crank, 165 mm arms
- Brakes: Tektro HD-M745
- Fork: RockShox Recon Silver
- Shock: X-Fusion Pro 2
- Wheels: Bontrager Line 30
- Dropper Post: TransX
- Drivetrain: Shimano XT w/ SLX chain and e*13 Plus crank, 165 mm arms
- Brakes: Shimano Deore 4-piston
- Fork: Fox 36 Rhythm
- Shock: Fox Float X Performance
- Wheels: Bontrager Line Comp 30
- Dropper Post: Bontrager Line
- Drivetrain: SRAM GX T-Type
- Brakes: SRAM DB8
- Fork: Fox 36 Rhythm
- Shock: Fox Float X Performance
- Wheels: Bontrager Line Comp 30
- Dropper Post: Bontrager Line
Some Questions / Things We’re Curious About
(1) How does the TQ HPR50 drive system perform on the trail? Trek’s claims of reduced noise and more natural power delivery sound great in theory, but are they borne out?
(2) Does the Fuel EXe keep the versatility that we so appreciated in the Fuel EX, or does it feel like a different sort of bike entirely?
(3) And who is going to be best served by this class of lightweight, lower-power e-MTBs in general, as compared to either a conventional MTB or a bigger full-power motorized one?
Bottom Line (For Now)
The Trek Fuel EXe has one of the most intriguing drive systems in the e-MTB market, and the new aluminum version brings the price of entry down substantially. We’ve got a Fuel EXe on the way for review, so stay tuned for more to come on the bike and the TQ HPR50 soon.
Cool to see this come down in price. I’ve got extensive time on the EX and EX-e. A few observations:
They handle very similarly.
The TQ is very quiet, and the noise it makes is not irritating.
The TQ motor (or Trek’s software tuning of same) rewards a higher cadence.
The app to customize motor performance is very elegant and simple, simple, simple. I retuned my power levels so 3 = factory 2, 1 = 1, and 2 = factory 1.5. Five minutes tops to do this.
I’ve been riding the Fuel exe 9.5 for a couple of months now and with a few upgrades it is a very capable bike.It’s light enough to throw around a bit and the motor system is ideal for my needs- I’m older and it allows me to ride with my young friends without getting so rinsed on the uphills that the downhills aren’t fun!! I’m riding uphill more often(anx I live next to a lift serviced bike park) and rediscovering trails that I haven’t ridden in years.I’d say this sort of bike is for the rider who wants tree s some assistance but doesn’t need or want the mega power and weight of a full power e bike.