Video: Trek Powerfly 8 FS review
We rode the Trek Powerfly in the high mountains of Switzerland
What is it?
We’ve spent enough time now with the Trek Powerfly 8 to give it a verdict. This 130mm travel full suspension Plus bike from Trek is based off the Fuel EX. And although a new category for them in the US, it’s a second generation product based on the many years of learning they’ve had selling e-bikes in Europe.
Check the video to see what we think.
//www.youtube.com/watch?v=wqKOR-EhTRo
Saris and Francis discuss the pros and cons of the Powerfly 8.
Pros
- Frame is incredibly stiff and is perfect for the demands of the e-bike
- New, Performance Line CX motor delivers torque smoothly and early
- Suspension is up to the task with the damping demands of the much heavier bike
- Plus tires give extra traction
- 1×11 drivetrain with no lift pulley to get the chain to clear the suspension linkage
- 500 WH battery is key for longer rides with a lot of climbing
- Good dropper and components selection
- $5000 actually delivers a pretty good value
Cons
- Chupacabra tires don’t have enough knobs for the task
- Big rotors are good but this can use more powerful brakes
- Display is smaller now but it could be made smaller still
- Its 50.5 lb weight makes it less agile on downhills and less playful
- Weight just makes the bike so unwieldy around the garage or the bike rack
- Rattling noises during descending
We upgraded our Trek Powerfly 8 with Maxxis Minion HighRoller II tires and Enve wheels.
Tech
The last model in the range is the $5000 Powerfly FS 8, which is essentially a Fuel EX Plus. Think 130mm of travel front and rear, 27.5+ tires, and boost spacing. In addition to identical travel and wheel size, the two bikes share similar geometries, as well as technology like Active Braking Point.
One of the crucial parts of the Powerfly 8, is what Trek calls a Straight Shot Downtube. Rather than using a traditional design that curves near the headtube to clear the fork crowns, the downtube on new Treks is straight till it meets the bottom bracket junction (or in this case, motor.) Ostensibly, this creates a lighter, stiffer frame. This pays dividends on a traditional bike but its gains are even greater on an e-bike. With 20 lbs of additional frame weight, frame stiffness has always been our biggest complaint against e-bikes. Frame flex was an issue in handling of previous e-bikes but it is much improved on the Powerfly
The Knock Block is designed to work with Bontrager stems, but can also be used with any stem of your choice.
The issue with the Knock Bloc design and straight downtube is the fork won’t clear when the bars are turned almost 90 degrees. Their solution is the Knock Block system, which uses a chip in the top tube to act as a fork stop. There’s also a bumper located on the underside of the downtube that acts as an added fail-safe.
In the high mode, the Powerfly has a 67.4-degree head angle and 338mm BB height. In the low (slacker) mode, it has a 66.9-degree head angle and 332mm BB. Photo by Dan Milner and Gaudenz Danuser
The Powerfly benefits from Trek’s Mino Link, which allows the end user to easily adjust the head angle and bottom bracket height. This flexibility are very handy on an e-bike since there’s less downside with climbing compromises. The rider is more free to pick geometry that works for them with less concern for optimized an optimized climbing position.
The Bosch Performance CX motor is designed for off-road use. The drive unit is said to be slightly smaller than other motor motors, which gives it better clearance over obstacles. Photo by Dan Milner and Gaudenz Danuser
The main difference between the Powerfly and Fuel EX Plus is the pedal assist motor. For 2017, all models in the Powerfly series use the new Bosch Performance CX motor. This system does not have a throttle. It is pedal assist only. If you’re not pedaling, there’s no power. And the power cuts out off when you reach 20 mph.
The two entry level hardtails in the Powerfly line use a smaller capacity 400Wh battery. The Powerfly 7 and FS 8 benefit from this 500Wh unit. Photo by Dan Milner and Gaudenz Danuser
The system is powered by a 500 Wh battery, which Trek claims has a range of 105 miles in eco mode, or 37 miles in turbo. These numbers appear overly optimistic in my experience, but power consumption can vary widely depending on riding style, terrain, weight, etc. The battery requires 4.5 hours to charge completely and there are four different power modes: eco, tour, sport, and turbo.
This is huge for us since the old 400 Wh battery always seemed to leave us with a drained battery before the end of the ride. This new one allows us 3 hour, 5000 foot adventures regularly.
Mtbr’s Take
E-bikes are far from perfect but they’ve come a long way in the last 5 years, with an amazing drivetrain now. The Trek Fuel EX Plus frame and wheel platform seem perfect for this type of bike. The bike rides and handles very well and even the most boring terrain becomes entertaining and rewarding.
Rating: 4.5 out of 5 
Price: $5000
More info: www.trekbikes.com
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