Bike Review: Bulls Wild Flow EVO RS Trail Bike


Photo: Pat Carrigan


There’s been a trend of superlight e-bikes this year, like the offerings from Specialized with their Turbo SL and Creo SL. These bikes offer less weight, but also less power and range than their Bosch- or Yamaha-powered counterparts for example. They’ve also ranged from higher-priced compared to many others to stratospheric (for example, the S-Works Turbo Levo SL will lighten your bank account by $14,000).

Bulls jumps into the fray with their newest Wild Flow with 29-inch wheels with 120mm of front and rear travel, and great components for a good deal less than the entry-level versions from other companies. But, has it worked?


In a unique twist on frame construction, the Bulls uses a carbon fiber front triangle and an aluminum rear. It’s lightweight, stiff, yet not bank-breakingly expensive. The blacked-out look may still be fashionable to some, but it’s grown weary by most now. However, owing to the color and integrated motor/frame design, you’ll have a tough time calling it out as an e-bike. If you’re looking for stealth, you’ve found it in the Wild Flow.


The FSA crankarms are carbon and wrapped in multiple directions for stiffness to allow more of your effort to transfer to the drivetrain. The drivetrain duties are handled with a Shimano Deore XT 1×11 kit with an 11-46T cassette.

A Fox Float 32 fork allow for confident rolling over technical terrain.



The suspension includes a Fox 34 Float Rhythm fork, which isn’t the beefiest on the market, but it provides a very sturdy yet plush 120mm of travel in the front, and a Fox Float DPS shock does the same for the rear. 

The Magura MT5 quad-piston hydraulic brakes use 180mm rotors. The rear brake rotor has an integrated magnet, and the speed sensor is built into the rear triangle near the dropout.

A Fox Float DPS shock rounds out the 120mm of front and rear travel.


A Selle Royal Verve saddle sits atop a KS dropper post with 100mm of travel. The stem and seatpost clamp are pre-wired with the MonkeyLink system that allows their lights to easily click into place. All the wiring is internal
and powered off the Fazua battery.


Bulls went with the 250-watt Fazua Evation motor, which is definitely one of the lightest mid-drive systems. The motor has 60 N/m of torque, and unlike many other mid-drives, it’s not built into the bottom bracket area; rather, it sits above the bottom bracket and drives the gears within. 

The previous versions of this system had to be powered on at the battery—requiring dropping the Drivepack from the downtube to turn on the system—if the system had been off for over eight hours. For 2021, Fazua has fixed this deep-sleep issue with their new 250X battery. 

The 225-Wh battery is minuscule and fits inside the motor case that clicks into the downtube. The motor makes up the other half. Because the battery is so small, carrying an extra battery in a hydration pack is easy ,and not nearly as heavy or bulky as most other systems’ batteries. The Remote FX display is very simple and integrated into the top of the downtube with a line of LED lights that change color depending on the power-assist mode. There are five LEDs, showing the amount of battery left in whatever mode color you are in. There’s green for Breeze (aka Eco), blue for River (medium) and pink for Rocket (high). 

The Fazua Rider app allows customization of several aspects of the motor’s power delivery, as well as displaying all kinds of information about battery life, speedometer, cadence, rider torque input, GPS navigation, direct access to Fazua service and more. 

The entire system, battery, Drivepack and bottom bracket weigh in at 11 pounds. Carrying a spare battery only adds 3 pounds. The bottom bracket integrates a torque sensor, and when the motor is disengaged, it provides virtually no resistance at the pedals. It is one of the lightest and stealthiest systems on the market. There is even an optional motor cover, so you can run without the motor and battery altogether for an even lighter ride, which also creates a storage compartment.


In today’s market, the 120mm of suspension travel makes it a short-travel bike, but that’s plenty for trail riding and is actually for some more serious, technical stuff. For someone looking for a light bike that’s easy to throw around, especially those looking for a lower-powered e-bike solution, this is a good choice. 


You would think that this diminutive motor wouldn’t put out much power, but you’d be wrong. At 60 N/m, it’s significantly less torquey than that of the Bosch CX or Yamaha PW-X2’s 8 N/m, but it’s still plenty, especially in
Rocket mode. 

We did 20 miles on one ride that included several thousand feet of climbing, and knowing we were going to explore, we took a second, fully charged battery with us for good measure. Surprisingly, the first battery got us a dozen miles in with a lot of climbing before we made the swap and ended up using about 20 percent of the second battery for the rest of the ride. Range anxiety is a factor if you’re used to 500+ Wh batteries, which are the norm on most e-MTBs these days. The incredibly light spare battery was almost unnoticeable in our hydration pack. 

Magura front and rear quad-piston disc brakes allow for great stopping power but also very good modulation.


The bottom bracket that serves as the transmission between the motor and the cranks offers virtually zero resistance when the motor is disengaged. When in Rocket mode, there are pawls in the bottom bracket that engage for just a second as the motor disengages, so the front sprocket then acts as if it is directly connected to the cranks. The transfer makes a sound like a very loud freewheel, but in lower modes, it does this silently.

The power button and motor controls are all in one control/display on the downtube.


At nearly 10 pounds lighter than most e-MTBs on the market, the Bulls has a wonderfully light and nimble ride. Playful and lively, we took it over flowy trails, technical stuff, loose dirt/sand, and it tracked beautifully and easily. 

If you’re interested in a spare battery, they run for about $500, and you can also get a battery bag to attach the spare battery to your bike or a downtube cover, which goes in place of the Drivepack and can be used for storage for about $100 each.

Photo: Pat Carrigan



We were impressed by the Wild Flow. It’s lighter weight than most full-suspension e-MTBs on the market, and among the super-light trend, it’s one of the least expensive on the market. Add to that the ease of swapping batteries on the trail if you are a power user and the overall great feel of the bike, and the Wild Flow is well worth a look.


Price: $5999

Motor: Fazua Evation 255W mid-drive

Battery: Fazua 252 Wh/36V

Charge time: 3.5 hours

Top speed: 20mph

Range: 15–25 miles (tested)

Drive: Shimano Deore XT, 1×11, 11-46T

Brakes: Magura MT5 quad piston, 180mm rotors (f/r)

Controls: Fazua

Fork: Fox 34 Float Rhythm, 120mm

Rear shock: Fox Float DPS, 120mm

Frame: Carbon front, aluminum rear

Wheels: Bulls  

Tires: Schwalbe Nobby Nic

Weight: 41.5 pounds

Color choice: Matte black

Sizes: 44/48/54cm



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