- Top of the line, full suspension, fat tire electric trail bike with RockShock Bluto and Monarch air, remote lockout for the fork, 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
- Basic pedals are easily bent and don't offer much surface area, no kickstand and no provisions to add one yourself aftermarket, Bosch Purion display is more basic and not removable, CX motor is louder and more power hungry
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The Monster E FS is one of the only full suspension, fat tire, electric trail bikes I have ever seen… aside from the Haibike SDURO Full FatSix, which uses a Yamaha mid-drive vs. Bosch. For the additional $300 here, you get a motor system with shift detection, higher RPM support (up to 120 pedal strokes per minute), and eMTB drive mode. It’s a product that hasn’t changed much since 2017, aside from using a different, more compact, display panel and moving towards an all-black paint job. This electric bike comes in two frame sizes, which is very impressive given the niche it fills, and I found it to be nimble and trail capable with 4″ wide tires vs. some of the heavier and slower 4.6″ and 4.9″ tires now rolling onto the scene. It’s a Class 1 product with a top assisted speed of 20 mph, so as to be legal on more mountain biking trails, but it’s also well-suited to sand and snow if you lower the tire pressure. One thing I really love about fat tire bicycles is how stable and comfortable they can be. With punched out rims to reduce weight, highly adjustable air suspension, and a sloping top tube, it’s practical and comfortable to mount. BULLS Couldn’t go quite as steep with their top tube because the Bosch Powerpack battery inserts down vs. from the side, and they didn’t have room for bottle cage bosses in this are either, but the split-pivot swing arm in the rear is designed to isolate lateral movement so the chain won’t buck or slip when the going gets bumpy. I really love the drivetrain on this electric bike because it’s a simpler, lighter, 1×11 setup than having multiple sprockets up front. When you combine the higher-end Shimano Deore XT derailleur with the Shadow Plus clutch, alloy chainring guard and surrounding guide-pully system above, it almost completely prevents chain drops as well as chain suck from below. Chain suck can sometimes be an issue with the smaller proprietary Bosch chainring in muddy environments when the chain isn’t as tight and there’s no riser pully… but it shouldn’t be an issue here. This is a purpose-built frame with excellent weight distribution, responsive power delivery, and plenty of braking power. If you’re actually going to ride in the snow, be sure to lower the tire PSI to ~5 (and consider converting the tires to tubeless), the flat grips will provide plenty of room for padded gloves and the adjustable-reach brake levers will be easier to grab and activate. This thing is not a novelty, it’s very capable and complete in my view. The only drawbacks are a higher price point, a somewhat limited display panel, a more exposed battery pack (compared to the new Powertube 500 from Bosch), limited cargo storage options, basic pedals, and no kickstand support.
Driving this beast is an internally geared mid-motor specifically designed for mountain biking applications. It’s the zippiest, most powerful, and heaviest Bosch ebike motor on the market, and it’s called the CX. Delivering up to 75 Newton meters of peak torque, it relies on three primary signals from the motor controller in order to activate. The system listens for rear wheel speed with a traditional magnet sensor on one of the spokes, pedal cadence, and pedal torque, over one-thousand times per second. Bosch designs sensors for all sorts of automotive equipment and smartphones like the iPhone, so the sensing technology here is something that really differentiates them. Even though this electric bicycle does not have a throttle, the higher levels of assist are so quick and fluid that it can almost feel like a throttle when starting out. As someone with knee sensitivity, I have come to appreciate this response when mountain biking because of my sensitive knee. This sort of performance does come at a price however, the battery will drain faster and there’s some electronic whirring noise that is demonstrated in the video review above. This motor weighs almost nine pounds, but at least the weight is positioned as low and centrally as it can be, and BULLS has designed an alloy skid plate to protect it from below. On the right side, a small 15 tooth sprocket spins 2.5 times for each crank arm revolution vs. using a one-to-one chainring. I have been told that this provides better chain grab and I suspect it allows for a greater mechanical advantage and more responsive starts and stops. When you’re navigating varied terrain, predictability is important. The responsive motor performance is balanced by large 180 mm hydraulic disc brakes from Magura with quad-piston front calipers that offer increased surface area for cooling and smoother stops. Coming back down to the bottom bracket, I appreciate the little alloy chainring cover, which will help pants slough away from the chain vs. getting greasy or snagged, and the chain guide riser pulley wheel that will keep it on track and clear debris. I feel like the drivetrain on this electric bike performs well and will withstand the rigors of different environments.
Powering the 2018 Monster E FS is a Bosch Powerpack 500. This is one of the lightest weight, high-capacity, electric bike batteries I have reviewed, and it’s also one of the most widely available. In addition to using the same case design and mounting interface as the older Powerpack 400 (which can also be used on this bike), it is backed by a two-year 1,000 cycle warranty and can be found at ebike shops all over the world. What this means is that you’ll be able to find a replacement more easily, or perhaps a second pack to extend or rides, or maybe rent or borrow a pack when traveling. Since high-capacity Lithium-ion batteries aren’t allowed on commercial flights, this could enable you to adventure to more places with YOUR bike vs. having to rent one on location. Compared to the new Powertube design, which is integrated into the downtube vs. attached on top of it, the Powerpack is more than a pound lighter (when you take into account the shielding below the Powertube), easier to remove for charing off-bike, and safer to carry around using the integrated loop handle. Since this is a heavier bike with big tires that produce more drag, suspension that can bob some of your pedaling efficiency away, and a power-hungry motor, it’s wonderful to have nearly half a kilowatt hour of capacity to burn through. And, refilling the pack is relatively quick with the included 4-Amp Bosch charger. Most electric bike chargers I have seen offer just 2-Amps of power flow and weigh at least 1.5 lbs. The Bosch charger weighs 1.7 lbs and is very compact. For those who need to reduce and save even more space, the company does offer a 1.1 lb 2-Amp travel charger. One of the main differences between the latest BULLS Monster and the 2017 version is that the display is smaller and does not have a Micro-USB power port. This could further extend the range of your battery, but it’s a trade-off with some consequences worth considering.
The display panel you get with the 2018 Monster is called Bosch Purion, and is mounted within reach of the left grip for easy reach while riding, without compromising your grip. It’s tough, relatively simple to use, and faintly backlit for easy use in darkness. Once the battery pack has been mounted and locked to the downtube (make sure you hear it click into place) just press the power button on the top edge of the Purion display and it will blink to life. The top area shows your speed in miles per hour or kilometers per hour (hold the minus key and tap power to switch between) and the bottom section shows your battery charge level. The charge indicator uses a 5-bar infographic with 20% jumps that leaves a bit to be desired in my opinion, but is relying more on amp hour flow vs. voltage to calculate, and thus does not bounce around as much as some less sophisticated products. A very similar 5-bar display is built into the Bosch Powerpack battery case, along the left side, and can be activated by pressing a little minus symbol button there. So, at least the two menus match and you can tell how full the pack is whether it’s mounted or not, but I would love to see Bosch move towards a battery percentage readout for more precision. In the center of the display, different trip menus can be accessed and explored by holding the minus button on the control pad. The main readout is assist level which includes Off, Eco, Trail, eMTB, and Turbo. Clicking plus or minus allows you to raise or lower support, and the eMTB mode is like a “do everything” mode that relies on pedal torque more than a set power band. It came in handy while test riding in sand and allowed me to focus and spend more attention and energy on balancing the bike and shifting gears. All Bosch CX motors get access to this eMTB setting, though older hardware may need a firmware update. It performs more consistently than actual strain sensors that I have tested, like the TMM4. So, the other menus in this center section are trip distance, total distance, and range. And you can access these by holding the minus key for a few seconds. Keep in mind, if you press plus or minus again, the readout will temporarily revert to assist level. Earlier, I complained about the 5-bar battery readout being less precise than it could be, but the range menu helps to make up for this. It’s one of the more advanced readouts that I have seen on any electric bike drive system and relies on the charge level, your last mile of ride performance, and the chosen level of assist to provide a very accurate estimate. Used thoughtfully, this menu will help you get there and back again without running out of juice… You might need to use lower levels of assist at times, but at least you’ll have the data to know when.
The Bulls Monster E Full Suspension electric fat bike is exciting, just looking at this thing gets my imagination going and it actually lives up to the visual presentation. The drivetrain is tough, the electronic systems are some of the most reliable and well-supported that I know of, and it offers enough power and precision to handle soft sand and snow. Super deep snow cannot be overcome by really any electric bike, this isn’t a snowmobile, but the added surface area and possibility for very low tire pressure gives you the best shot you can really ask for with a product like this. The motor kicks on so quickly, that it can feel like you have a throttle to work with, and that’s a deciding factor in soft terrain. While the 2018 model appeared to be 0.2 lbs heavier than 2017 and the display is smaller and not removable, many Bosch Certified dealers can help you upgrade to the larger Intuvia if you want. Many companies have switched to the smaller Purion to save money, look stealthier, and be tougher (especially on e-mountain bikes) but as a near-sighted rider, I like the intuvia, and it’s Micro-USB charging port to run my phone’s GPS. The punched out rims on this bike help to save weight and improve cushion, the chainring guard and pulley system will protect your snowpants, and the angled top tube will make mounting and stepping off into soft sand or snow a less painful experience for your crotch. And, the two frame size options really extend the experience here, for people of different sizes. I wish it had provisions to add a kickstand at the back end of the left chainstay, but I see why they didn’t include a stand stock… to reduce weight and rattling. Just be careful when laying this bike down, lay on the left side or lean against a wall by positioning the back tire against the wall with the bike angled out. Once you’ve had a fun ride and the bike is dry, use air pressure to dust it off or remove sand. After this, you can use a damp rag and some cleaning spray like this to wipe it down. The display, battery, and motor are all highly water resistant, but you wouldn’t want to submerge the bike or spray it hard with water. For reference, I reviewed the medium sized (smaller) frame which is 46 cm and have provided my own measurements in the stats section above. As always, I will do my best to answer comments below and you can connect directly with other owners and enthusiasts in the BULLS Ebike Forums. Big thanks to Bulls for partnering with me on this review and providing a couple of different models to compare, along with some staff to hang out with and go for a ride on the beach. It was an awesome experience, I have enjoyed watching them grow as a company over the past few years, and feel that their support and network of shops have done a great job providing a high level of customer service. One final note, you could add integrated lights to this system with the help of a shop and then hold the plus button on the display to turn them on/off and I love that they went with multi-shift triggers and a two-way high shifter to bring this up to the cross country and trail level. The rear suspension has a lockout lever and the front has a remote lockout so you can reduce bobbing and easily transition from hard packed to bumpy trail without hopping off.
- One of the only full suspension fat tire electric bikes I have seen, and 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 2018 model has a more integrated color scheme, everything is black so the motor casing, battery box, and cables blend together
- 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 120 mm travel air suspension from RockShox with adjustable sag, rebound adjust, lockout, and remote lockout on the front, 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 locking Ergon grips and the compact Bosch Purion display panel, there’s plenty of room for the triggers and seat post dropper lever on the right and I like the low-rise bars for a more upright body position on cross country and trail terrain
- 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
- These Ergon grips aren’t aren’t as thick as some of the other models, so you can wear gloves and still get a nice handle on them, the Magura brake levers offer adjustable reach which also suits gloves or people with longer/shorter fingers
- Thru-axles on the front and rear wheels 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 included pedals aren’t my favorite, they don’t offer as much surface area or durability as even cheap Wellgo pedals and you could upgrade to lightweight sealed magnesium platforms with adjustable pins without spending a lot, the stock pedals can get bent and become sharp over time when laying the bike on its side
- There’s no kickstand included and I didn’t see provisions for adding one yourself aftermarket, this means the bike will always have to be leaned against walls or posts, so be careful with the disc brake rotor and derailleur on the rear portion of the bike because they are sensitive, always lean the bike onto its left side to protect the drivetrain
- 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
- Very few full suspension bikes come with front or rear racks, you could mount a seat post beam rack on this bike, but it could get bumped side to side, since there are no bottle cage bosses or other ways to easily transport gear, you might need a backpack or hydration pack
- Since Bosch Performance Line motors use a smaller chainring and reduction gearing system to improve response time and chain retention, there is some friction when you pedal unpowered, the chainring spins 2.5x for each crank revolution but there is no drag when coasting
- Since the seat tube has a bend halfway down, you cannot drop the seat post very far and might need to modify the post (by cutting with a hack saw and then sanding sharp edges) to get it to fit your leg length properly
- 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 Performance CX motor uses the most power and produces the most noise of any of Bosch’s current generation drive systems, thankfully the battery offers a lot of juice and the sound of those knobby tires mostly covers up the electronic whirring
- Official Site: http://www.bullsebikes.com/product/monster-e-fs-3/
- More Pictures: https://photos.app.goo.gl/chTSo9AkWHk20dJQ2