Trek Powerfly Launch in Verbier, Switzerland

The Trek Powerfly descends with confidence, but it's still on the heavy side. Photo by Sterling Lorence​

Trek has been selling e-bikes in Europe for a while and they have learned a lot. These bikes have gone from niche offerings to becoming a major part of their European business. In a few short years, e-MTBs in Europe have gone from nothing to about 30% of all their mountain bike sales. And they're selling them as fast as they can make them. The growth path in Asia is similar.

In the U.S., however, e-bike sales are growing at a slower rate, as there's a lot more regulation and controversy surrounding these motorized two wheelers. It's currently less than 10% of the mountain bike business and Trek is approaching it more cautiously, offering just four Ebike models in the States versus 15 across the pond. And they are working with cycling advocacy organization People For Bikes in coordinating with trail managers to define what e-bikes are and where they can be used.

Mtbr recently took a look at the new Trek Powerfly with 130mm of front and rear travel to see what it had to offer.

Trek Powerfly

The Trek Powerfly battery is now integrated into the downtube. Photo by Sterling Lorence​

Frame Integration

One of the most visible changes is the battery pack now sits inside, instead of on top of the down tube. This shifts the weight of the battery lower on the frame for improved overall stability. It also makes the bike look more normal, without the huge battery in the front triangle.

And though there is room for a water bottle, there are no cage mounts since they would need to be right on the battery. That's disappointing but we're sure straps and other bottle holder systems will work because the space for the bottle is now there.

New Frame Features

  • Internal cable routing for rear derailleur
  • E2 tapered head tube
  • 437mm chainstays
  • 31.6 seat tube for dropper compatibility
  • Stealth dropper post routing
  • 130mm FS or 150mm LT versions (150mm version only available in Europe)
  • Boost hub spacing
  • Fits up to 2.8 tire

Trek Powerfly

Instead of taking the ski lift, we "climbed" to the top of the Verbier Bike Park.​

SRAM EX1 Drivetrain

One of the most significant developments in e-bikes is the creation of e-specific drivetrains. To use a 2x11, 1x11 or even 1x12 on an e-bike works but is clearly not necessary.

And e-bikes are harder on the chain and cassette since there is more torque and power going through the system. Typically, a rider can put out 250 watts of peak effort and the motor can add 500 watts during bursts. That means 750 watts of power, which wears down a chain and cassette rather quickly. SRAM's EX1 is an 8-speed system so the chain, cassette, and chainring are all thicker. Perhaps more importantly, the chainline is straighter, putting less stress on the drivetrain.

Trek Powerfly

This tough singletrack climb was done several times in one day aboard the Powerfly. Photo by Sterling Lorence​

Smooth, silent shifting is the mantra, and with the 11- 48t cassette you won't get hung up in the steepest terrain. We hate the fact that the EX1 shifter limits you to one shift at a time, but it really protects the drivetrain, especially under peak loads. And on EX1, one shift is like two shifts anyway. Instead of 15% cassette jumps on a standard drivetrain, the EX1 employs 30% jumps. This optimizes the balance between assisted power and gearing shifts. It feels natural and gets the job done with less need for double-shifts to keep one's rhythm and cadence.

SRAM EX1 Drivetrain Features

  • More robust and durable
  • 1x8 drivetrain
  • 11-48 cassette
  • Single click shifter

Trek Powerfly

The Trek Powerfly assist motor now delivers more torque earlier. Photo by Sterling Lorence​

Battery and Motor

The Powerfly is equipped with a top-end Performance Line CX motor and 500Wh battery pack. Starting with mid-drive commuter systems a few years ago, the first Trek e-MTBs were a compromise, but a good start. Now the motor is specifically tuned for the demands of mountain biking.

The motor delivers a healthy 75 nm of torque and does so quickly. Where one had to climb at 7mph previously to get up steep hills using maximum torque, the CX motor now delivers all of its torque in low rpms, in speeds as slow as 3mph, as long as it senses the rider is making a pedaling effort.

The battery is also now upgraded from the 400 Wh of previous years. It has 25% more capacity, so you can do a 3-hour with 5000 feet of climbing no problem as long as you use normal assist levels.

Trek Powerfly

The Trek Powerfly now includes an e-MTB mode that delivers minimal assist during low efforts, but max torque when the rider puts in a big effort. This eliminates the need to switch assist modes during the ride. Photo by Sterling Lorence​

Display Features

  • Smaller, ergonomic controller
  • Control assist levels and displays easily
  • Standard on all Powerfly models
  • Long life 500Wh battery on every model

Another notable feature is the addition of an e-MTB mode that delivers minimal to maximum assist, depending on rider effort. Previous Bosch systems and other brands force you to select between four modes (or more) to pre-determine how much you want the motor to help. This was okay for commuting, but for mountain biking the terrain is so varied that you want the motor to help just a little on most low effort areas but you want it to give full boost when the trail pitches up and you're about to start walking. Previous systems required the rider to switch all the time. But this new e-MTB mode does the switching for you.

Battery Features

  • Integrated battery in the downtube
  • Tool-free access and easily removable battery
  • Can be charged in the frame
  • Places weight lower in frame for more stability

Wheels and Tires

Tires in the Bontrager line are not ready for this bike yet, with the only available plus tire being the fast-rolling Chupacabra. Instead Trek sourced the Schwalbe Nobby Nic for the job, and it does a fine job in the rear. However, we cannot wait for the arrival of the Bontrager XR4 or something equivalent in plus sizing. This will allow the Powerfly to reach its full potential with good cornering side knobs.

Meanwhile, the new Bontrager Powerline wheelset features heavy-duty rims that exceed the strength tests used for the wheels on Trek's DH bikes. And the brakes are perfectly suited to the task, with 200mm rotors on SRAM's excellent four-piston Guide RE brakes.

Powerline Wheels

  • e-MTB specific wheels
  • Plus rim built to downhill impact standards
  • 32-hole, thicker rim sections
  • Rapid-drive hub
  • Found on Powerfly 9, FS 9, LT 8, LT 9

Trek Powerfly Launch in Verbier, Switzerland

The Trek Powerfly delivers great torque even at low pedal rpms. Photo by Sterling Lorence​

Fork Talk

The Fox 36 fork may look like just a regular Fox 36, but this e-bike specific version gets thicker walled upper tubes and a solid crown to boost strength and handle the extra forces that a heavier bike can exert. The simple but effective Fox GRIP damper has also been tuned with more damping support to be optimized for e-MTBs.

Fox e-Fork Features

  • e-MTB specific fork
  • Stouter chassis, longer durability
  • 34mm stanchions
  • Tuned for e-MTB and enduro
  • Found on Powerfly 9, FS 9, LT 8, LT 9

Trek Powerfly Launch in Verbier, Switzerland

The Trek Powerfly has the right components to descend confidently. Photo by Sterling Lorence​

The Ride

The RE:aktiv damped 130mm rear suspension handles hits of all sizes and the frame is laterally stiff enough so you don't have to ride it like an e-bike on aggressive descents. You just ride it. The front and rear suspension are matched for its weight and you're free to push its limits. Brakes are awesome and it equalizes the extra bike weight with this new found stopping power.

Trek Powerfly

The Trek Powerfly can barrel over trail obstacles, but it still rides like a heavy e-MTB.​

It's not as easy to boost on small rocks and booters, as the elevation achieved is about half of a normal bike. But get it on a real jump and it will soar high and far.


  • Powerfly 9 FS Plus
  • Trek Powerfly 7 Plus - $5000
  • Trek Powerfly 5 FS - $4500, 27.5 wheeled model without the SRAM EX1 drivetrain
  • Trek Powerfly 9 FS Plus - will not be available in North America in 2018

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