- A fat tire electric trail bike with a RockShock Bluto suspension fork, remote lockout, 11-speed Shimano Deore XT drivetrain with Shadow Plus clutch, robust skid plate and alloy drivetrain guides
- High-torque Bosch Performance Line CX motor with eMTB drive mode, sand and snow capable if you lower the PSI on the Schwalbe Jumbo Jim tires, premium Magura MT5 hydraulic disc brakes with adjustable-reach levers
- Relatively lightweight and well balanced, available in two frame sizes for improved fit, high-capacity 500 watt hour battery pack with 4-amp quick charger can be filled on or off the frame, ABUS battery core can be keyed-alike to locks
- No integrated lights or Monkey Link setup, non-locking flat grips, no bottle cage or fender bosses, Bosch Purion display is more basic and not removable, CX motor is louder and more power hungry
To run the forums, host the website, and travel, I charge a universal service fee for my reviews. This review was sponsored by BULLS. My goal is to be transparent and unbiased, this video and written review are not meant to be an endorsement of BULLS products.
The Monster E S is a hardtail, mid-drive, Bosch powered, fat-tire ebike from BULLS. At $4,899, it is cheaper than the full suspension version, but still pretty sophisticated and premium compared to most fat-tire bikes out there. For fat-tire bikes nowadays, it is common to see a hub motor, throttle, and some entry level parts thrown on for good measure. The Monster E S on the other hand is using the top of the line Bosch Performance CX mid-drive motor, has hydraulic brakes, and uses a RockShox front suspension. The bike comes is aluminum alloy and comes in 2 frame sizes (46cm and 51cm). Only 1 color here, but I do like the green and white accents and there is a lot of black on black color matching throughout, so overall, a great look. The hardtail is nice here since it brings the cost down from the E FS version and it also has rack bosses. No fender bosses here however from what I can tell, but I suppose you could find a seat post mounting one. That rigid seat post is 30.9mm so you could add a suspension seat post if you felt it was lacking in comfort. I think the comfort is still pretty good here, especially from the 26” x 4” Schwalbe Jumbo Jim fat-tires. They are rated for 5-30psi which is a great range. I love to take it down all the way to 5psi for sand or snow, it really shines here. However, do be careful with the lower psi as it creates loose rubber folds that can cause pinch flats AKA ‘snake bites’. I love that they have these awesome square hole punched out rims with black tire liner, they reduce weight a lot, create some give, and add to that comfortable feeling too. 15mm spacing through axle in the front and a 12mm spaced 9mm axle in the rear, both with quick release. Assisting in more comfort is the RockShox Bluto RL Solo air shock. It has about 100mm of travel, has a remote lockout, and is pretty lightweight. Overall, the setup is 52lbs, which is not bad for a fat-tire with suspension. Other things I see here are a clear plastic sticker slap guard, tapered headtube, and non-locking flat rubber grips.
Driving this electric bicycle is a trail optimized mid-motor from Bosch called the Performance Line CX. It’s rated up to 75 newton meters, considerably more than the standard Performance Line and Performance Line Speed, which peak at 63nm. Given the slightly heavier footprint of this bike, it’s a great choice. It probably inflates the price a bit, but you do benefit from a special eMTB drive mode that only the Bosch CX offers. In this mode, which is the third step up just before Turbo, the motor performance can operate from 120% to 300% based on how hard you push. The other modes (Eco, Tour, and Turbo) have more limited power bands. This drive mode was introduced as a way to make motor performance more automatic and intuitive for mountain bikers who might be focusing on trail obstacles and gear shifting. For the Monster E S, which has super smooth Shimano shifting and is designed for trail riding, eMTB mode is just one more way that the bike can be ridden without distraction or thought. Just hop on, arrow up to eMTB, start pedaling, and the bike will respond naturally based on how hard you pedal. All current generation Bosch Performance Line motors weigh roughly 8.8lbs, which is more than Shimano, Yamaha, or Brose drive units. The CX produces more noise, especially in high power and a higher pedal speeds, and it also uses more energy… but it’s known for being reliable and having a good network of certified repair shops. This motor responds based on three signals: rear wheel speed, pedal cadence, and pedal torque. It uses some of the most advanced sensors and can even sense when gears are being shifted. Mechanically, the bike the bike is operated by an 11 speed, 11-40 tooth cassette via Shimano Deore XT with a shadow plus clutch. The Shimano setup has shifters going 2 high and 4 low. For brakes you get these Magura MT5 180mm rotor hydraulic brakes, really a top notch choice for stopping this beast. All in all, there is a lot of fun in the way it rides, it is very clean, fast, and agile.
Powering the motor and backlit display panel, is a 482.4watt hour battery pack from Bosch. The battery, a PowerPack 500, clicks neatly into the downtube. It may not be as clean as the newer PowerTube Bosch batteries, but I am happy they went with it here. It is lighter weight and is compatible with swapping out any other Bosch PowerPack batteries. You can charge the pack off of the bike frame or plug into the port when mounted on the bike, however, it is near the crank arm so do be careful. Lithium-ion cells, including the 18650 cells used in this pack, tend to be very reliable if you maintain them at 20% to 80% capacity when not in use and store in a cool dry environment vs. extreme heat or cold. I frequently store my electric bike indoors because it isn’t as heavy or smelly as a moped or motorcycle, and this keeps it clean and safe while also protecting the battery from extreme temperatures. Charging happens quickly here, thanks to the included 4amp Bosch charger, yet it’s relatively compact and lightweight compared to others on the market. Bosch does sell an even smaller, lighter charger, that delivers 2 amps. They call this the travel charger and I read many comments from people who use it at a work site or carry it along in a backpack or pannier. In closing, the PowerPack weighs less than the PowerTube at 5.7lbs vs. 6.3lbs, but you’ll want to make extra sure to hear it click into place on the frame when mounting before rides. If you have an older PowerPack 400, it will work with the same interface as the PowerPack 500, so you can swap packs or rent and borrow if you travel frequently.
Once you’ve charged and secured the battery pack, operating the bike is pretty straight forward. The control panel consists of a grayscale LCD with four surrounding buttons. The power button is built into the top edge, a + and – button is reachable along the left front portion, and a walk mode button is built into the lower edge. Pressing the power button brings the LCD to life quickly, and a faint white glow is active at all times making it readable in low lighting conditions. I’ve created an in-depth guide to the Bosch Purion display panel, with video overview, in the EBR forums. It’s not removable however, and the Micro-USB port on the right edge is not active for charging as is the case with the larger Bosch Intuvia. I much prefer the Intuvia for its size and additional menus (shift recommendation, clock, max speed, average speed, and trip time), and some shops can upgrade you to this display for ~$200. With Purion, you’ve got a streamlined and simple interface with the necessities including trip distance, total distance, and range estimate. You can cycle through these menus by holding the – key, and you can reset trip distance by holding – and + simultaneously for a couple of seconds. The main portion of the display is used to show your current speed and assist level. If you’d like to change units from miles to kilometers, you simply hold – and tap the power button. Anytime you change from one assist level to the next, the menu briefly changes. In my experience, the buttons don’t click in as consistent as Intuvia, and there’s no dedicated light button (hold + to activate the lights if you’ve got the CX motor), but it gets the job done. If this was the only display that Bosch produced, I might be a little more enthusiastic about it here, it is a great display, I think I’ve just grown to appreciate the charging, removability, color, and Bluetooth features on some of their nicer displays. Most of the mountain models I review here do spec Purion, to hide and protect the display. For me, it would have been worth an additional $50 or $100 in the price tag given how expensive the bike already is, but it’s not a deal killer by any means.
In conclusion, the bike is a lot of fun and the more premium setup really shines. If you get a chance to see the review video, check it out, I loved how responsive the system was when I took it on some beach rocks, it was awesome! However, the Monster E S does have some tradeoffs. There was no integrated lights here or a Monkey Link setup like some of the other BULLS bikes, so that was kind of a bummer. I also noticed no locking grips and no bottle cage bosses. And I should also mention the Performance Line CX is an extremely impressive motor, but it does create more noise and as well as some drag if you are taking it to the max or are riding with the electric system off. All in all though, BULLS is a great company that offers a dealer network, comprehensive warranty, and wonderful support. They use a lot of high quality components and it really shows in this bike. I really did have a ton of fun and I am excited I got the chance to check this one out, so a big thank you to BULLS.
As always, I welcome questions and feedback in the comment section below. Whether you own a previous version of the bike, have taken a test ride, or are brand new to the space, my goal is to provide an objective and honest resource. You can also join the BULLS Ebike forums and share your own photos, videos, and review updates to help others! Have fun out there, and ride safe :)
- A more premium fat tire bike with suspension, it uses one of the best motor and battery systems available, Bosch CX with the PowerPack 500, and is available in two sizes for improved fit and ride comfort
- The motor is very responsive and right there for you immediately, I was impressed how it handled the sandy rocks I got to take it on in the video, very much a capable machine
- Schwalbe makes premium tires and these ones can be converted to tubeless to save weight and run at lower pressure, I love that the rims are punched out for weight savings and give
- Premium drivetrain with eleven gears, a one-way clutch to keep the chain tight on rough terrain, an alloy chainring protector and sturdy alloy guide with narrow-wide sprocket so you should never struggle with drops, chain slip, or chain suck (which can sometimes happen in muddy conditions on the proprietary smaller Bosch chainrings)
- Trail-ready 100mm travel air suspension from RockShox Bluto with remote lockout, black anodized coating on the stanchions provides strength and improves sliding
- The motor is positioned for maximum ground clearance but also has an alloy skid plate underneath for added protection if you have a rock strike
- Both the motor and battery pack are positioned low and center on the frame, this improves handling, reduces unsprung weight compared to hub motors, and I feel that BULLS has done an excellent job blending both items into the tubing design of the frame so they look good
- The cockpit is very clean and sturdy, you get the compact Bosch Purion display panel, and there’s plenty of room for the triggers
- Both wheels offer quick release, which combines with the removable battery to make this bike lighter and easier to transport, I always take the battery off when loading onto bike racks
- The Powerpack 500 offers a lot of capacity in a compact, super lightweight package, the mount for this battery is backwards compatible with the older Powerpack 400 battery if you have one, I like that both packs have an integrated handle and can be found worldwide for easier renting or replacement
- This Bosch charger is one lightest and fastest models around, offering 4 Amp output and weighing just 1.7 lbs, it doesn’t require any dongles to connect and charge the battery off or on the bike
- The Bosch CX motor offers a lot of zip and torque, up to 75 Nm with nearly 570 watt max, it’s one of the most reliable mid-drive systems around and now features an eMTB mode with variable power output based on pedal torque… so you can leave the assist setting alone and focus on shifting gears and steering, this is particularly useful on soft terrain
- It’s nice that Bulls designed this frame with a steeper top tube to lower stand over height because sometimes if you jump off into sand or snow, your feet could sink and you might rack yourself on a higher tube
- Hardtail doesn’t always mean less, with this frame, they added rear rack bosses, so you could really load this thing up for a weekend adventure
- Thru-axle on the front wheel for maximum stiffness and strength, tapered head tube is also stronger and works with nicer forks like the Bluto here
- The battery lock core is made by ABUS and comes with a code card so you can purchase locks “keyed-alike” and have fewer keys floating around causing confusion
- Bosch designs all sorts of sensors and mechanical hardware for the automotive, home appliance, and tools categories and is one of the few companies to offer shift detection on their ebike motor systems, this is designed to protect the chain, cassette, and derailleur as you ride and shift gears and is especially relevant and useful with the high torque Performance Line motors like this
- Walk-assist has been enabled on this ebike which means you can get help moving it forward if you get a flat tire or have to hop off on a particularly difficult or steep section of trail, just press the walk mode button at the base of the display and then hold the plus button when in any of the four levels of assist, switch gears to change walk speed
- The Performance Line CX is an extremely impressive motor, but it does weigh more, creates more noise, and adds some drag if you are taking it to the max or are riding with the electric system off
- While the Bosch Purion display panel is less vulnerable, because it’s small, the screen isn’t as easy to read as the larger Bosch Purion and it isn’t removable, you get fewer menus and readouts and there’s no Micro USB port built in for charging (just for diagnostics), but some shops can help you upgrade to the Intuvia if you want it
- There is no kickstand here which I was surprised to see, but it does have kickstand provisions and it looks like they are mounted out of the way of the crank arm which is nice as that eliminates pedal lock when reversing
- There is no integrated lights here or a Monkey Link setup like some of the other BULLS bikes, so that seems like kind of a missed opportunity given the strength of the PowerPack 500
- No fender or bottle cage bosses are present, but this was likely due to that standard placement of the Bosch PowerPack 500
- The charging port for the battery (when mounted to the frame) is very close to the left crank arm and could get snagged or bent there… so be extra careful with the bike when charging, don’t walk it backwards because the cranks will turn
- The non-locking flat rubber grips seem a bit out of place given the premium components and comfort throughout the bike
- Official Site: https://www.bullsebikes.com/