Trek Powerfly 4 Gen 4 Review

Robb Dorr
Written by Robb Dorr
Co-founder, Cycling Enthusiast
Kristy Snyder
Edited by Kristy Snyder
Professional Editor

35 mi


20 mph


8 hrs


52.78 lbs




Trek Powerfly 4 Gen 4 Review: Takeaway

The Trek Powerfly 4 is the cheapest electric mountain bike made by Trek. This doesn’t take away from its great components and rideability, though. It’s an eMTB designed for lighter trail riding with its larger wheels that smooth out the bumps on the rough spots. Relatively light yet powerful, the Trek Powerfly 4 Gen 4 is an ideal electric mountain bike that doesn’t break the bank.

Ideal for...

Non-competition cross-country riding
Light downhill/singletrack riding
eMTB riders on a budget

E-Bike Overview

The Bosch Performance CX motor gives a real kick with up to 85Nm of torque, meaning that you can pull away on a steep and muddy hill with confidence. Power delivery is smooth so you won’t spin the rear wheel should you push too hard. The Bosch smart system offers enhanced ride control with navigation and activity tracking via the eBike Flow app.

Packaged with the Bosch Performance CX motor, is their Walk Assist mode that helps push your e-bike up those tough hills you’re bound to encouter. The LED remote let’s you enable Walk Assist and control the level of pedal assist you need. The LED lights are bright and easy to see, even in bright sunlight.

One thing that Trek does with this electric bike is fit different equipment to different-sized machines. For example, on the XS and S framed machines, it has a 27.5” wheel size, while on the M, L, and XL sizes have a 29″ wheel. The frame on the smaller e-bikes are also slightly different, offering a curved top tub for sizes XS and S, while frame sizes M, L, and XL have a straight top tube.

Trek has thought about everything, not surprisingly. Rack and kickstand mounts are readily avilable, as well as an integrated speed sensor for those riders looking to use the PowerFly 4 as more of a trekker than a day-rider trail e-bike.

Reasons to Buy

If you want an electric bike but don’t want to empty your bank account, the Trek Powerfly 4 Gen 4 is a very good machine to consider. At the lower end of the premium spectrum, the Trek Powerfly 4 will be worth every penny when it comes to an electric mountian bike that will look after you on the road or trail.

Designed not to embarrass you on the trail, it works well on longer cross-country rides. Its battery will be good for a 35-mile ride on tougher terrain, and the power of the Bosch Performance CX motor will leave you breaking a sweat only if you’re going easy on the battery.

When it comes to speed control, the electric bike won’t let you down even on steep tracks in wet conditions with its Tektro hydraulic brakes, and on 203mm rotors, they won’t fade even if used a lot.

Things to Consider

If you want a genuinely inexpensive electric mountain bike, there are others like the Rad Power brand of electric bikes, but few pack as many high performance components as the Trek Powerfly 4 Gen 4. This isn’t the cheapest eMTB out there, but it is very inexpensive for a high-end machine.


Size: M , L , XL–Alpha Platinum Aluminum, Removable Integrated Battery (RIB), tapered head tube, Control Freak internal routing, Motor Armor, Boost148, 12mm thru axle. Size: XS, S–Frame has a curved top tube.
SR Suntour XCM 34, coil spring, preload, lockout, tapered steerer, 44mm offset, Boost110, 15mm thru axle
Max fork travel
120mm, XS: 80mm
Hub front
Formula DC-511, 6-bolt, Boost110, 15mm thru axle
Hub rear
Bontrager Approved DC-3248, sealed bearing, alloy axle, 6-bolt, Shimano 8/9/10 freehub, Boost148, 12mm thru axle
Bontrager Connection, double-wall, 32-hole, 20mm width
Size: XS , S–Bontrager XR3 Comp, wire bead, 30tpi, 27.5x2.35''. Size: M, L, XL–Bontrager XR3 Comp, wire bead, 30tpi, 29x2.30''
Bosch PowerTube 500Wh, smart system
Bosch standard 4A, 110V, smart system
Bosch Intuvia 100, smart system
Bosch LED remote, smart system
Bosch Performance Line CX
Shimano Deore M4100, 10 speed
Rear derailleur
Shimano Deore M5120
Shimano Deore M4100, 11-46
Brake Set
Tektro HD-M275 hydraulic disc, 203mm rotors

The specs above come from the manufacturer and may vary from what you’ve experienced. Notice something that needs correcting? Let us know.



Offering up to 85 Nm of torque, the light but punchy Bosch Performance CX motor delivers the power you need for riding off-road, including rapid direction changes and tackling steep climbs as you journey around the woods or mountain.

Its Bontrager XR3 Comp tires won’t go quickly on hard, flat surfaces due to higher rolling resistance, but this isn’t what the Powerfly 4 is about — it’s about fun in the mud and on loose surfaces. As such, the motor won’t achieve great flat-out speeds, but it’ll more than make up for it in raw power over the rough stuff.


The 500 Wh battery on the Powerfly 4 will give you a good day out on singletrack and a reasonably long day in the saddle on an off-road adventure. However, there’s no option for a range extender, so if you’re looking for more than 35 miles per charge, choose an eMTB with a range extender or a 625+ Wh battery.

Leaving your gear at a base while doing singletrack will give you more range, but if you’re carrying your pack on an adventure, this will eat into your mileage. Muddy terrain and foul weather can impact range, too.


Sat in a trekking position, you’ll use your upper body to shift your weight according to riding conditions. This could mean you get tired in your arms, chest, and shoulders after a long ride.

Sizes XS and S in the Trek Powerfly 4 range come with 27.5” wheels, while sizes M, L, and XL come with 29” wheels. Either way, they’ll smooth out the rough terrain.

The XS version of this eMTB hardtail electric bike comes with an 80mm travel SR Suntour fork, while all larger sizes have a 120mm travel fork. Both are well-suited to rough terrain.


Though Trek offers a lifetime warranty on the frame, if you haven’t looked after this e-bike, the warranty may be voided.

Clean the bike and oil its working parts after every ride. Keep an eye on chain stretch — change it when it gets to 1 mm per link, and look out for bent/broken teeth on the cassette and front chain wheel. Also, keep an eye on brake pads and hydraulic fluid. Though the Powerfly 4 is waterproof to an extent, take care when it comes to river crossings, as it isn’t designed for complete immersion!


Being a serious electric mountain bike, the Trek Powerfly 4 also looks the part. The clean lines and nice shapes of the frame along with its overall geometry combine to make for a good-looking eMTB.

The choice of colors is good too, from the loud red and black scheme to the muted gray and black. Overall, this bike looks like it means business when thrown about the tracks and trails.

Our Research Methodology

We personally research and test every e-bike featured in our reviews and guides to provide accurate, data-driven recommendations. Learn how we review.

About Our Editorial Team

Robb Dorr
Written by Robb Dorr
Co-founder, Cycling Enthusiast
Robb is a massive cycling enthusiast who has more than 20 years of non-motorized cycling experience. He started to lower the barrier of entry to cycling and reduce the intimidation people can experience when getting into the cycling world.
Kristy Snyder
Edited by Kristy Snyder
Professional Editor
Kristy Snyder is a professional writer and editor living in Pittsburgh with over 10 years of content creation experience. When she's not contributing to, Kristy enjoys reading, practicing yoga, drinking beer, and hitting up rail trails.

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