A ride so agile, you’ll forget it’s a fat bike!


With previous rides aboard the Bulls Monster hardtail, we found one of the few fat-tire e-bikes that we actually liked to ride in all conditions. By adding rear suspension, Bulls has upped the ante in terms of off-road capabilities and created a bike that just begs to be ridden in the dirt.



In addition to the attractive black-and-gold graphics scheme, the Monster E FS just keeps getting better with great components like the RockShox Monarch shock and beefy Bluto fork. Add to that Bulls’ great geometry and a low top tube that can be stepped over. Topping all this off is a Bosch Performance Line CX motor, the best and most powerful in the industry currently. With a 15t front sprocket (Bosch motors turn 2.5 times for every one revolution of the cranks, making it equivalent to a 38t front sprocket), 11-40t in the rear and 75 N/m of torque, this monster truck of bikes can climb virtually anywhere, and it can also haul bananas down a trail, all without running out of gears.

A Bosch Intuvia display is very easy to read, and it displays everything you need for at-a-glance information. You can toggle things like average speed, total distance and current range, and there is a micro USB port underneath.



Fat bikes are an acquired taste for some­—not just in appearance but in ride quality as well. If you ride on off-camber singletracks, the fat bike ride might not be for you. The massive, round tires basketball right off the trail, but if you ride in rutted trails, these same tires tend not to get wedged in. They also have traction for days in sandy conditions, whether that’s sandy trails or on the beach, and in snow. Drop these down to 5 psi and there’s practically no surface they won’t tackle.

The knobs on the tires themselves aren’t the most aggressive, but they provide great grip on every surface we rode them on, including pavement.


Surprisingly, the Monster is even a fun street cruiser. It feels a little like a motorcycle because of the big tires and plush suspension. And with the big knobby tires, people will get out of your way because they’ll definitely hear you coming! One thing to note about the big 4-inch knobby tires is that when it comes to transporting the bike, many standard platform racks can’t handle tires that big. Some have optional extra-wide trays that will, though. Check your local bike shop.

We never ran out of gears with Shimano’s 1×11 drivetrain.



Before we ever took this bike out on dirt, we took it to the streets for some fun. For something that weighs north of 50 pounds and has huge tires, it feels reasonably nimble. No, really! Even though the tires will ride over any and everything, pre-loading the suspension lets you bunnyhop over a lot of road and trail obstacles.

“On dirt, it was right at home. You don’t even have to pick a line—just bulldoze your way through anything!”

The noise the tires make is nice, as they definitely announce your presence; no bell required. If you’ve ever worried about people being bothered by motor noise, or even hearing it, they won’t with this bike. The tires overpower any sound the motor makes. The tires offer ample grip for acceleration and, when aired up, little rolling resistance. Tire-pressure modulation is everything with fat tires; high pressure (up to 30 pounds) rolls great on the street. Varying lower levels are great on dirt, down to 5 psi for sand/snow.

Off-camber fire roads are fine, but off-camber singletracks can be really rough with these big tires.


That said, we took it down to the beach with 20+ psi and rode across the dry sand with no real issues. There’s plenty of power with even midrange gears and Sport or Turbo assist modes to ride right across. Turning on sand is a learnable skill; you just have to turn very slowly.


As expected, once on dirt, the bike is right at home. You don’t even have to pick a line—just bulldoze your way through anything! Fire roads with big ruts from the recent rains didn’t faze the bike. It just goes and goes and keeps on going.

We had Hall of Fame BMX racing legend Harry Leary loose on the Monster for his first-ever ride on an electric bike. He uttered the requisite, “Whoa!” when he first took off, but quickly settled into the bike that sits perfectly somewhere in between a bicycle and a motorcycle. Much closer to the bicycle, Harry said he loved the power and said it took him a bit to get used to having some power on a bicycle and modulating it using the brakes, which have power-cutoff switches.

Magura brakes were more than enough stopping power, especially with the quad-piston MT5 calipers on the front brake and MT4 dual piston in the rear. It has great modulation and enough power to lock up the wheels if you wanted to.


On one previous test bike that used the RockShox Bluto fork, we felt it to be a bit spindly, but for some reason it feels rock solid on the Monster. In fact, in these days of increasing amounts of suspension travel, the Monster’s overall 120mm of travel front and rear is enough for some pretty big stuff and big drops. The entire bike feels solid, with the build quality you expect from Bulls.


The Bosch CX is the perfect motor for the Monster. It has ample power in four modes: Eco, Tour, Sport and Turbo. We found ourselves toggling between Tour and Sport 95 percent of the time. Eco is pointless on the bikes, unless you’re just trying to overcome the extra weight of the motor and battery on the bike. On the other end, Turbo is only useful on really steep sections, but by then you’re often leaning so far forward that you unweight the rear wheel and lose traction. You have to carefully modulate upshifting higher than you expect to by very carefully distributing the weight of you and the bike.


The CX motor itself is protected by an aluminum skid plate that keeps the motor safe from those times you do bottom out the suspension or accidentally case a jump.


Magura brakes provide plenty of braking power to control speed even on steep downhills. The big tires help with all the extra grip. In normal braking on a regular bike, 75 percent of your braking power comes from the front wheel when using both brakes. Because the brakes have four pistons up front and two in back, that ratio may be higher still with the Monster.

A drop-off that normally scares us proved to be a really fun hit on the Monster. The bike’s suspension and tires provide ample confidence.


Our bike came with a 400-watt-hour battery. The bike now ships with a 500-watt-hour battery, which offers 25 percent more range. Even with that, Bulls claims “up to 130 miles,” which to us is overly optimistic. It does make sense that even if you weigh over 200 pounds and use Turbo mode and climb everything in sight, you’d still make the minimum claim of 26 miles. We’ve done rides that far on other bikes that have required more than one battery, and we don’t weigh that much and rarely use Turbo mode. The Monster E FS could handle that ride easily with just one battery.



We wouldn’t recommend this bike to anyone as their only off-road bike. You have to be a rider who will mostly ride this bike for its specific capabilities. It’s great for people who live in areas that have a lot of sand or snow; in other words, soft surfaces that need a lot of traction. The Monster E FS is definitely a fun bike, and as far as fat bikes go, it’s surprisingly agile. The low geometry, medium-wide bars and high-end suspension allow it to float across anything.



MSRP: $5299

Motor: Bosch Performance Line CX, 350W

Battery: 36V/13.4 Ah/500 Wh

Charge time: 4.5 hours

Top speed: 20 mph (with assist)

Range: 26–100 miles

Drive: Shimano Deore XT 11-speed, 11-40t

Brakes: Magura MT5/MT4 hydraulic disc brakes, 180/180mm discs

Controls: Bosch Intuvia

Fork: RockShox Bluto RL Solo Air, 120mm, 15mm Maxle

Frame: 7005 Aluminum

Rear shock: RockShox Monarch RT, 120mm

Tires: Schwalbe Jumbo Jim Snakeskin, 26×4.0

Weight: 52 lb.

Colors: Black/yellow

Sizes: 46cm and 51cm

Comments are closed.