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Bulls E-Stream EVO AM 4 Review

The Bulls E-Stream Evo AM 4 is a brawler on the descents with an impressive distance range thanks to its large battery storage capacity.
Top Pick Award
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Price:  $5,399 List
Pros:  Good controls, huge distance range, confidence inspiring at speed, good component spec
Cons:  Heaviest in test, sluggish at low speeds
Manufacturer:   Bulls
By Jeremy Benson ⋅ Senior Review Editor  ⋅  Dec 21, 2018
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83
OVERALL
SCORE


RANKED
#2 of 6
  • E-Bike Controls - 10% 7
  • Downhill Performance - 35% 8
  • Climbing Performance - 20% 8
  • Power Output - 15% 9
  • Distance Range - 20% 9

Our Verdict

If you've never heard of Bull bikes, you're not alone. Some of our testers had never seen or heard of them until the day they started riding our test model. The E-Stream EVO AM 4 we tested comes nicely equipped with a beefy enduro-ready build with 150mm of front and rear wheel travel, a stout RockShox Lyrik fork, and relatively modern geometry numbers. Wide rims and grippy 2.8 Schwalbe rubber help to maintain traction and tear through corners. This bike really comes to life at speed with a calm, stable, and confidence inspiring demeanor that begs to be ridden fast, although testers found it be a bit sluggish at lower speeds. The Brose motor system provides lots of smooth power with 4 customizable support settings and user-friendly controls. It also has a massive 650Wh battery that gives the bike a huge distance range, though it adds a bit of weight to this beefy rig. Overall, testers were impressed with the E-Stream EVO AM 4 and we awarded it with our Top Pick for Range and Battery Life.

For 2019, Bulls has updated the E-Stream AM 4. The primary differences are the change to a Fox 36 Float fork, and an increase in battery capacity to 750Wh to ride even further on a single charge. The price has also increased to $6,299. June 2019


Compare to Similar Products

 
Awards Top Pick Award Editors' Choice Award Best Buy Award   
Price $5,399 List$5,950 List$4,830 List$5,299 List$4,999.95 at REI
Overall Score Sort Icon
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Star Rating
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Pros Good controls, huge distance range, confidence inspiring at speed, good component specversatile, fits water bottle, least e-bike looking, good battery life, low center of gravityReasonably priced, good distance range, well rounded performance, solid component specSmooth and consistent power output, modern geometry,Cushy suspension, digital display, meaty tires
Cons Heaviest in test, sluggish at low speedsno digital display, more abrupt power assist cutoffHeavy, sluggish handling at times, controls/display are difficult to readNo digital display, wimpy tires and fork, center of gravity feels highLess torque, shorter distance range, inconsistent power output
Bottom Line The Bulls E-Stream Evo AM 4 is a brawler on the descents with an impressive distance range thanks to its large battery storage capacity.The Specialized Turbo Levo Comp returns to our e-bike test with a well rounded performance that earns it our Editor's Choice Award, again.The Giant Trance E+ 2 Pro is well rounded and reasonably priced earning it our Best Buy Award.The Instinct Powerplay Alloy 50 is close to greatness but is held back by its controls and components.The Ghost Hybride SL AMR S1.7+ looks interesting on paper but doesn't come together well on the trail.
Rating Categories Bulls E-Stream EVO AM 4 Specialized Turbo Levo Comp Giant Trance E+ 2 Pro Instinct Powerplay Alloy 50 Ghost Hybride SL AMR S1.7+
E Bike Controls (10%)
10
0
7
10
0
6
10
0
6
10
0
5
10
0
7
Downhill Performance (35%)
10
0
8
10
0
9
10
0
8
10
0
6
10
0
7
Climbing Performance (20%)
10
0
8
10
0
8
10
0
8
10
0
7
10
0
7
Power Output (15%)
10
0
9
10
0
8
10
0
8
10
0
7
10
0
5
Distance Range (20%)
10
0
9
10
0
9
10
0
9
10
0
9
10
0
7
Specs Bulls E-Stream EVO... Specialized Turbo... Giant Trance E+ 2... Instinct Powerplay... Ghost Hybride SL...
Motor System Brose Drive S (250W) 650Wh Specialized 2.1, Custom Rx Trail-tuned 250W Giant SyncDrive Pro Yamaha Dyname 3.0 250w Shimano Steps DU E8000
Fork RockShox Lyrik RC Boost Solo Air 150mm RockShox Revelation Charger RC 150mm Fox 36 Float Rhythm 150mm RockShox Reba RL E-Bike 140mm RockShox Revelation 140mm
Motor Power (torque) 90Nm ? 80Nm 108Nm 70Nm
Battery Size (Wh) 650Wh 500Wh 500Wh 500Wh 504Wh
Measured Weight (w/o pedals, Medium) 55.15 lbs 48.3 lbs 52lbs 3oz 52lbs 4oz 50lbs 14oz
Suspension & Travel RockShox Deluxe RT 150mm Future Shock Rear (FSR) - 150mm Maestro 140mm Ride 9 Adjustable SLAMR 140mm
Wheel size (inches) 27.5+ 29 27.5+ 29 27.5+ front, 29 rear
Shock RockShox Deluxe RT RockShox Deluxe RT Fox Float DPS Performance EVOL RockShox Deluxe Debonair RT RockShox Super Deluxe Coil R
Frame Material Aluminum ALUXX SL aluminum FORM Alloy
Frame Size Tested Large Medium Medium Medium Medium
Available Sizes 44/49/54 cm S-XL XS-XL S-XL S-XL
Wheelset Formula Hubs/Bulls Rims Roval Traverse 29, 30mm internal Giant AM 27.5+ rims/Giant eTracker hubs 35mm internal rim width Sun Duroc SD37 Alex MD30/35 rims with Ghost Disc Hubs
Front Tire Schwalbe Magic Mary Snakeskin, TLE, Apex, 27.5 x 2.8 Butcher Grid 29 x 2.6 Maxis Minion DHF EXO 27.5 x 2.6 Maxxis Rekon EXO 2.6" Maxxis Minion DHF EXO 29" x 2.5"
Rear Tire Nobby Nic Snakeskin, TLE, Apex, 27.5 x 2.8 Butcher Grid 29 x 2.6 Maxxis Rekon EXO 27.5 x 2.6 Maxxis Rekon EXO 2.6" Maxxis Minion DHR II EXO Maxx Terra 27.5" x 2.8"
Shifters Shimano Deore XT SL-M8000 SRAM S700 Shimano SLX 11-speed SRAM GX-1E Shimano SLX 11-speed
Front Derailleur N/A N/A N/A N/A N/A
Rear Derailleur Shimano Deore XT RD-8000-GS, 11-speed SRAM GX, 11-speed Shimano XT 11-Speed SRAM NX 11-speed Shimano XT
Crankset SR Suntour 38T + Miranda Praxis 2D Alloy 32T Praxis Wavetm 36T Race Face Ride Cinch 34T Ground Fiftyone 34T
Crankarms not specified, but at least 170 165mm 170mm 160mm
Bottom Bracket not specified Race Face BB92 not specified
Cassette Shimano SLX CS-M7000-11 , 11-speed, 11-42T SRAM PG-1130 11-42t Shimano HG-M7000, 11-46T SunRace CSMX8 11-46T Sunrace CSMS8 11-46T
Chain KMC X11E KMC X11ET KMC e. 11 Turbo KMC X11-1 not specified
Saddle Selle Royal Seta M1/Bulls Body Geometry Phenom Comp 143mm Giant Contact Neutral WTB Volt Race WTB Koda e-bike
Seatpost KS LEV-Integra X-Fusion Manic 150mm Giant Contact Switch dropper Race Face Aeffect Dropper Satori Sorata Fury
Handlebar Bulls Specialized Trail 780mm Giant Contact 35 Trail 800mm Rocky Mountain AM 760mm Ghost Race 780mm
Stem Monkey Link Specialized Trail --mm x ---mm Giant Contact SL 35 Rocky Mountain AM Ghost Race
Brakes Magura MT5 hydraulic disk brakes SRAM Guide RE 4 piston 200mm rotors Shimano BR-MT5220 4-piston 203mm rotors SRAM Guide T TRP G-Spec Trail S
Grips Ergon Specialized Sip Grip Giant Rocky Mountain Lock On Light Ergon
Measured Effective Top Tube (mm) 638 600 610 590 595
Measured Reach (mm) 435 435 449 446 450
Measured Head Tube Angle 67 65.3 66 66 66.5
Measured Seat Tube Angle 74 74.5 74.5 75.9 75.8
Measured Bottom Bracket Height (mm) 354 348 342 342 340
Measured Standover Height (mm)
Measured Wheelbase (mm) 1230 1200 1215 1194 1210
Measured Chain Stay Length (mm) 462 457 474 448 460
Warranty Lifetime Five Years on frame not specified

Our Analysis and Test Results

Bulls is a lesser known brand in the North American market, but that is likely to change as electric mountain bikes continue to grow in popularity. They produce a huge line of full suspension and hardtail e-MTBs as well as commuter and cruiser style models. The E-Stream EVO AM 4 model we tested falls roughly in the middle of their range of full suspension models and has a quality build for the price. It impressed our testers with its downhill prowess, stability at speed, impressive range, and battery life, and smooth and powerful power output. It's the heaviest model we tested by a fair amount, but you'll be hard pressed to notice when you're riding this powerful model.

Performance Comparison


Just out for a rip while testing the E-Stream EVO AM 4. This bike is really a blast to ride.
Just out for a rip while testing the E-Stream EVO AM 4. This bike is really a blast to ride.

E-Bike Controls


The controls on the E-Stream EVO AM 4 are among the best in the test. There is a Compact Sports Interface (CSI) control unit mounted on the handlebar by the left grip which has several buttons for power, lights, changing power output, a small joystick, and an easy to read digital display. Turning the power on is as simple as pressing the power button on the top of the controller, and it fires up almost instantly. This controller has decent ergonomics with the buttons you press most frequently while riding, to shift through the four power output settings, located closest to the thumb on the side of the unit. The display is somewhat small, but it is bright and easy to read even in very sunny conditions. The main page displays your current speed in the center with 4 bars at the top of the screen that shows which output setting you're using and 4 bars at the bottom of the screen that displays remaining battery life. The small joystick on top of the unit allows you to scroll between pages to view your power output displayed in watts, ride distance, total distance, and remaining mileage range. Additionally, the control unit can be synced with your phone or heart rate monitor via Bluetooth to an app called Naviki that has navigation and mapping features. You can also adjust the power output settings to your preferences. No other bike we've tested has this amount of information available on display.

The control unit has pretty good ergonomics  an easy to read display  and more functions than the competition.
The control unit has pretty good ergonomics, an easy to read display, and more functions than the competition.

There is an additional battery display on the downtube which shows the remaining battery charge. When you press the button at the top of this display a number of small green lights illuminate depending on remaining battery life. Charging is done with a Rosenberger plug which is nearly identical the that used on the Specialized Turbo Levo Comp. This plug has a secure magnetic connection that holds it in place on the charging port. The charging port is located lower down on the downtube and covered with a magnetic rubber cap. The charging port itself is recessed within the frame about an inch and a half or so, and it is difficult to see when you are attempting to attach the plug to it.

The battery life display on the downtube at full charge.
The battery life display on the downtube at full charge.

The E-Stream EVO also has a system called "Monkey Link" integrated into its design. This includes a magnetic water bottle system and magnetic mounts for lights on the bottom of the stem and on the back of the seat clamp. We didn't have the chance to test the lights, but this is an innovative system that allows you to quickly and easily mount or remove the lights with power supplied by the bike's battery, and turn them on and off with the button on the control unit. We did test the water bottle, and we found it easy to attach and remove, it even stayed in place during the rowdiest of descents. Monkey Link makes a range of lights, reflectors, fenders, and bottles.

The integrated Monkey Link system is pretty slick. Get the water bottle close and it automatically snaps into place with the magnets.
The integrated Monkey Link system is pretty slick. Get the water bottle close and it automatically snaps into place with the magnets.

The controls on the AM 4 are most similar to those found on the Trek Powerfly which has a similar all-in-one control and display unit mounted on the left side of the handlebar. The controls on the Bulls bike have a more ergonomically friendly layout, and the display is easier to read. We think this is also a better system overall than those the Specialized Turbo Levo Comp which have buttons that are harder to reach. The Shimano Steps controls found on the Ghost SL AMR are also quite nice with a digital display mounted by the stem.

Downhill Performance


The E-Stream EVO AM 4 is an all-mountain bike with a beefy build that performs well on the descents, especially at speed. Due to the weight of the bike, the heaviest in the test at 55 lbs, nimble and agile aren't the first words that come to when describing its downhill performance traits. Interestingly, it isn't impossible to get this bike off the ground or manual as long as you are carrying some speed. This bike gets up to speed in a hurry with a stable and confidence inspiring feel complemented by a stout RockShox Lyrik fork, comfortable cockpit, and big 2.8" tires.

This bike prefers to go fast  luckily its pretty darn good at it.
This bike prefers to go fast, luckily its pretty darn good at it.

The E-Stream EVO AM 4 has good geometry numbers, but with a 67-degree head tube angle we wouldn't exactly call it slack. Once the rider adds weight to the bike and the rear suspension settles into its sag we would say that head tube angle decreases by a half to full degree, the front end of this bike doesn't feel as steep as that measurement suggests. For comparison, all of the other bikes in this review, except for the Trek Powerfly, have head tube angles in the 65-degree range. The AM 4 has a 74-degree seat tube angle, a moderate 435mm reach, and a long 1230mm wheelbase. The moderate reach measurement is a good middle ground that doesn't feel too long or too short. The long wheelbase is partially due to the long 462mm chainstays and is one of the reasons this bike feels so stable at speed but struggles somewhat in low-speed technical sections of trail.

Point it and let 'er rip  this bike likes to go fast and inspires confidence the confidence to do so.
Point it and let 'er rip, this bike likes to go fast and inspires confidence the confidence to do so.

The 150mm RockShox Lyrik RC is an appropriate fork specification for a bike of this weight. It gives the front end a stout and solid feel and is highly tuneable with its air spring, compression and rebound adjustments, and bottomless tokens. The 150mm of rear suspension is handled by a RockShox Deluxe RT that feels well matched with the front end. The cockpit feels pretty dialed with a short Monkey link stem, 780mm handlebar, and KS LEV Integra dropper seat post. The spec of 2.8" Schwalbe tires, Magic Mary in front and Knobby Nic in the rear, further inspires confidence and adds to this bike's smooth and stable feel. Once this bike gets up to ludicrous speed, slowing and stopping it is handled by Magura MT5 brakes with 203mm rotors both front and rear. These brakes provide heaps of power, but testers weren't wild about their lever feel or the odd noise they make when you apply them.

Balanced suspension  meaty tires  and powerful brakes all benefit the downhill performance of the E-Stream EVO AM 4
Balanced suspension, meaty tires, and powerful brakes all benefit the downhill performance of the E-Stream EVO AM 4

The downhill performance of the E-Stream EVO AM 4 feels most similar to that of the Ghost SL AMR but better. Both bikes come to life at speed but struggle a bit in tighter technical sections of trail. In the case of the Bulls bike, this is due mostly to the long wheelbase and heavier weight. This in contrast to the Specialized Turbo Levo Comp which strikes a good balance with a more versatile performance on the descents.

Climbing Performance


The climbing performance of the E-Stream EVO AM 4 is surprisingly good, we might even call it fun. It has enough power on tap make climbing as exciting as the descents, and it scrambles up just about anything. The drive unit's four support settings make it easy to dial it in for the trail, conditions, or workout you're after. The Brose Drive S unit provides very consistent power output that comes on very smoothly the moment the pedals start turning and continues for a second or so after they stop. This is especially nice in technical sections of trail where you may jockey your pedals to avoid striking them on rocks and makes it less likely to bog down under the weight of the bike.

With all that power on tap climbing on the Bulls is a breeze.
With all that power on tap climbing on the Bulls is a breeze.

The E-Stream EVO AM 4's geometry plays into the way it handles on the climbs. The long wheelbase makes it a little tougher to get around tight switchbacks and through tricky rock gardens, although the steeper head tube angle helps keep the front end from wandering. The 74-degree seat tube angle isn't quite as steep as the competition, but it still puts the rider in a pretty neutral position above the pedals. The moderate reach feels good, neither cramped or too stretched out. The rear shock does have a dampening switch for use when climbing, although like with most pedal-assist bikes, it seems a bit unnecessary unless you're riding pavement for a long time. The large 2.8" Schwalbe tires also provide loads of traction for clawing your way over rocks, roots; you name it.

E-bikes make riding uphill way more fun  such is the case with the Bulls.
E-bikes make riding uphill way more fun, such is the case with the Bulls.

It is worth mentioning that the E-Stream EVO AM 4 is a bit of a bear if and when you do get to a section of trail that may be too steep to climb. This bike weighs 55 lbs and as far as we can tell it doesn't have a walk feature to assist you if you end up in a hike a bike situation.

Power Output


Testers were very impressed with the performance of the Brose Drive S pedal assist system on the E-Stream EVO AM 4. Like most others, they claim a nominal power output of 250 watts, but one of the main things that was impressive was the smoothness of it, and this is due to the belt driven system. The drive unit engages with no jerkiness or twitchiness, just smooth pedal assistance the moment the pedals start turning. This is in contrast to other systems that can feel twitchy and anxious to go, or the Specialized 2.1 motor which doesn't respond until the pedals turn about a quarter rotation. It is also pretty quiet, one of the quietest in the test, on par with the Specialized motor in that regard. The Bulls bike doesn't announce that you're riding an e-bike the way a louder motor does. We also rode this bike with the motor off, and there wasn't any noticeable resistance which is nice considering the weight of this rig.

Blurry fast speeds are easily reached on the E-Stream EVO AM 4.
Blurry fast speeds are easily reached on the E-Stream EVO AM 4.

In addition to the smoothness of the engagement of the pedal assistance, testers also appreciated the lack of abruptness when the pedals stop turning. The extension of the power band for a moment after you stop pedaling makes a world of difference and helps to prevent this bike from feeling like dead weight. The drive motor has four output settings, Cruise, Tour, Sport, and Power, and those settings are customizable to match your preferences. The drive unit also boasts 90Nm of torque, the most of all models we tested, and it has no problem hitting its top assisted speed of 20mph.

Range


The simple fact that the E-Stream EVO AM 4 comes with a 650Wh battery automatically gives it a longer distance range because it has more storage capacity. This is nearly 30% more battery life than the other competitors in this review which have 500Wh or 504Wh batteries. In theory, this would result in approximately 30% more distance range, but that varies with factors like rider weight, output setting, trail conditions, weather conditions, etc. Bulls claims a range of 137 miles under optimal conditions, and while that really sounds impressive, it would be nearly impossible to achieve that kind of mileage while on a normal mountain bike ride. To test the range on the Bulls, we took it for a not so casual 24-mile ride with over 4,600 vertical feet of climbing. During the ride, it was used primarily on the highest output settings, Sport and Power, and when we were finished, it still had a bar of battery charge remaining on the display. We feel this is quite impressive.

With a 650Wh battery you might eventually have to ditch your friends when they run out of juice.
With a 650Wh battery you might eventually have to ditch your friends when they run out of juice.

It's not exactly fair to compare the distance ranges of the other bikes we tested to that of the Bulls E-Stream since the storage capacities of the batteries are quite different, but we'll do it anyway. Our top distance range performer was the Rocky Mountain Instinct Powerplay which traveled 20 miles and 4,297 vertical feet. Our second longest lasting competitor, the Giant Trance E+, went for 19.02 miles and 4,000 vertical feet. Based on those numbers it's clear that the Bulls can travel about 20-30% farther than the Rocky Mountain and the Giant. If you're looking for the most battery life and longest distance range, the Bulls is the best that we've tested. While most models come with 500Wh batteries, several options come with 650Wh and even 750Wh storage capacities. Batteries are heavy, and the larger the battery, the more it and your bike weigh.

Build


The component specification on the E-stream EVO AM 4 is nothing mind-blowing, but it is definitely nice for the price. It all starts with their 7005 Aluminum frame, which is beefy and stout from front to back. The Brose Drive S pedal assist motor is integrated into the frame at the bottom of the down tube and around the bottom bracket. Above that, the 650Wh powerpack is also built into the downtube for a super clean look. RockShox parts were chosen to handle the suspension duties with a 150mm Lyrik RC Solo Air fork and a 150mm Deluxe RT in the rear. Testers had no qualms with the suspension on the Bulls, it is highly tunable and felt sturdy enough to handle this heavyweight machine.

The Lyric fork provides stiff and precise steering with plenty of squish.
The Lyric fork provides stiff and precise steering with plenty of squish.

Shifting responsibilities were left to an 11-speed Shimano XT derailleur and shifters. Shifting was precise as expected, and the Shadow clutch on the derailleur plus a chain guide helped prevent any unwanted chain drops. It has an FSA crankset with a 38-tooth ring and an SLX 11-42 11-speed cassette that provides plenty of range given the pedal assistance available.

The 11-speed drivetrain.
The 11-speed drivetrain.

Braking is handled by a powerful set of four-piston Magura MT5 brakes with 203mm rotors front and rear. Testers didn't love the lever feel or the interesting sound of the Magura stoppers, but they did work well. The cockpit consists of a short Monkey Link stem attached to a modern width handlebar with Ergon grips. There is the addition of a KS LEV Integra seat post to drop it down and out of the way on descents. One thing we didn't love about the cockpit was the fact that the seat post remote wasn't the under-mount 1x shifter style. This is likely because the e-bike controls take up a fair amount of real estate on the left side of the bar, and they would conflict. Our test model had the KS Polycarbonate remote on the right side of the bar, not a deal breaker but it takes a little getting used to if you're accustomed to something else. Rounding out the cockpit is a Selle Royal saddle with Bulls branding. Not the most comfortable saddle in the world, but not horrible either.

Other than the dropper post remote the cockpit of setup is pretty well put together.
Other than the dropper post remote the cockpit of setup is pretty well put together.
cockpit

Rounding out the build is nice wide Bulls rims laced to Formula hubs with boost spacing and thru-axles front and rear. Mounted to those rims are some 27.5 x 2.8" Schwalbe tires, Magic Mary in the front and a Nobby Nic in the back, which provide plenty of traction both climbing and descending.

Side view of the Bulls  the motor and battery are cleanly integrated into the design compared to many other models on the market.
Side view of the Bulls, the motor and battery are cleanly integrated into the design compared to many other models on the market.

Best Applications


The E-Stream Evo AM 4 is a great option for the rider looking for a stable, confident descender with plenty of power, and a longer distance range and battery life. It's not the most playful bike around, but it comes ready to rumble with a nice build, innovative features, a quiet motor, and a 650Wh battery that can take you where you want to go.

Big 'ol 2.8" tires give confidence in the corners.
Big 'ol 2.8" tires give confidence in the corners.

Value


At a retail price of $5,399, the AM 4 is comparable in price to the other bikes in this review give or take a few hundred dollars. For that price you get roughly 20% more battery life and potential distance range, plus a well spec'd bike that doesn't need any upgrades to be a blast on the trail. Considering how well equipped and fun to ride it is, we feel it represents a pretty good value assuming you're looking for a fast and powerful electric mountain bike.

The Bulls is a great e-bike  one of the best we've tested so far.
The Bulls is a great e-bike, one of the best we've tested so far.

Conclusion


Testers were thoroughly impressed with the E-Stream EVO AM 4. This bike's combination of stability at speed, smooth power output, long battery life, and a nice build instantly made it a tester favorite. It's low-speed handling, and heavier weight left a bit to be desired, and in the end, it was bested by the Specialized Turbo Levo Comp for the Editor's Choice Award. That said, we still think it is a great option, especially for the rider seeking more battery life and a greater distance range.

Other Versions and Accessories


Bulls makes a wide range of electric mountain bikes, both full suspension and hardtail models, in a variety of builds and price points. They make two versions of the E-Stream EVO AM including the AM 4 model reviewed here.
The E-Stream EVO AM 3 ($4,999) shares the same frame, battery, and drive unit as the AM 4. The component specification is quite similar although it has a RockShox Yari RC fork, a Shimano Deore drivetrain, and Nobby Nic tires front and rear.

Monkey link also makes a line of magnetic accessories that are compatible with the monkey link mounts integrated into the design of the AM 4. These include lights, water bottles, and fenders. More information can be found on the Monkey Link website, and accessories can be purchased from several online retailers.


Jeremy Benson