- An all-mountain style electric bike with longer travel 150 mm air suspension from RockShox, an internalized downtube battery from Bosch, and three frame size options
- Fatter 2.8" plus sized tires provide increased traction, reduced deflection, and improved comfort while remaining stiff and responsive because of thru-axles and longer Boost hub spacing
- Ergonomic locking grips from Velo, remote seat post dropper from Kind Shock, quad piston hydraulic disc brakes from Magura, 11-speed Shimano Deore XT drivetrain with Shadow Plus clutch
- Responsive Bosch CX motor delivers an "all in one" eMTB drive mode designed to keep you focused on riding and shifting gears vs. adjusting power settings, the Bosch Purion display panel is more limited than Intuvia, the bike is a bit heavier with the Powertube integrated battery
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Bulls has quickly established themselves as a leader in the electric mountain bike category in the United States. Models like the EVO AM 3 and 4 cater to a niche category of mountain riding called “all mountain” which calls for longer travel suspension than cross country or trail. The AM 3 is the more affordable Bosch powered model featuring the new Powertube 500 battery, which is completely hidden in the downtube. Priced at ~$5.5k, you get three frame size options, a solid two-year comprehensive warranty, and access to a growing network of BULLS dealers and Bosch Certified electric bike shops that can work on the drivetrain. The beauty with all of these new mid-drive powered electric bike is that most of the additional weight is unsprung and positioned low and center. Handling is great, and the rigid 15 mm and 12 mm thru-axles with longer Boost hub spacing provide stiffness and strength that can support rugged environments and high-volume tires. The Schwalbe 2.8″ Nobby Nic tires used here can be run tubeless for decreased weight and lower PSI, which improves comfort and traction if you’re willing to compromise a bit on efficiency. But another benefit of mid-motors is that they leverage the rear cassette (with 11 sprockets in this case) to operate more efficiently, providing excellent range when shifted thoughtfully. Working on the drivetrain and wheels is hardly different from a non electric bike and because both shocks are air vs. spring, you can really dial in performance for your body weight and ride style. One of the highlights I noticed with some of the new 2018 BULLS models is MonkeyLink accessory points. There’s a special stem mount and seatpost clamp pre-wired with power from the battery so you can connect lights or a rear fender magnetically. On the downtube, even on the smallest frame size, there’s also a pair of bottle cage bosses which can be used with the twist-mount MonkeyLink water bottle adapter. It’s really surprising how many electric bicycles forego bottle cage bosses but on a recreational bike like this, without cargo rack support, it’s really nice to have when you get thirsty. Note that the stem mount is not really adjustable (nor did I see an angle adjust on the MonkeyLink sample headlight) so the one downside seems to be that the headlight beam will only shine at one angle which could be a little high or low depending on the steering tube angle… which is more raked out on this bike to handle bigger hits on downhill sections.
Driving the AM SIX50 EVO AM 3 is a Bosch Performance Line CX motor that is beautifully tilted and integrated into the downtube for maximum ground clearance and visual appeal. Over the past year or two, more companies have been experimenting with motor integration and BULLS has been a leader, minimizing the plastic casing size surrounding the motor and blending the color scheme to help it disappear. Note the fluorescent yellow skid plate running along the bottom. This motor is top of the line in terms of torque output and responsiveness from Bosch, delivering up to 75 Newton meters and ranging from 250/350 to 570 watts. It’s enough power to climb virtually any trail as long as you shift down to a lower gear. Bosch supports a range of chainring sizes, smaller being ideal for climbing, and the AM 3 runs a 15 tooth sprocket vs. 18, 20, and 22 seen on some of the urban models from Bulls. If you’re new to Bosch drive systems, you may be alarmed or confused by such small chainrings, but these sprockets spin 2.5x for every crank revolution and are said to improve chain grab and possibly improve responsiveness and motor efficiency. The downside is that the chain gets pretty close to the chainstay and if you shut the motor off, there’s a bit of mechanical friction being produced with each pedal stroke through the reduction gearing. It may also be difficult to swap out the chainring since it’s a proprietary part and not using an industry standard spider or bolt pattern. Thankfully, there’s a Velo slap guard to keep your paint in shape, a metal chainring guard to reduce drops and protect your pant leg (if you’re wearing pants while mountain biking), and a decent rear suspension design that stays vertical and shouldn’t cause slack (it reminds me of split pivot). Furthermore, the Shimano Deore XT derailleur and 11-46 tooth cassette provide excellent range for zero to 20+ mph pedaling, which is the max assisted speed, and a one-way clutch allows you to increase chain tension for those bumpy sections. Just click the little grey lever on the side of the derailleur into the up position. And for those wondering, yes, you can definitely pedal and coast 20 mph uninhibited, it’s only pedaling that is slightly impacted by the motor’s internal gearbox. On a final note here, I like that the Shimano trigger shifters provide two-way action for high and a multi-shift for low because it matches high performance riding and terrain. This bike is very capable and not watered down.
Powering the motor, backlit display panel, and optional MonkeyLink compatible lights is the brand new Bosch Powertube 500. A 36 volt 13.4 amp hour battery pack that is completely hidden inside the downtube! Bulls has done an excellent job with their frame design in my opinion, using 7005 Aluminum alloy throughout, and including paint-matched plates to protect the base and sides of the battery. I’m relatively new to the Powertube design but love how stealthy it is. Unlike some other electric mountain bikes that stand out as being “different” because their battery packs are bolted on, the BULLS SIX50 EVO AM models blend in and might pass as non-electric from a distance. For those wishing to avoid questions while simultaneously achieving the lowest battery-weight positioning… it’s the clear winner. But it doesn’t solve the electronic hum produced by the motor in higher levels of assist and it doesn’t makeup for the still bulging design of the motor. Compared to the Brose powered BULLS models, Bosch stands out a bit. But the performance is zippier and I noticed that the battery pack does not flop out as easily when unlocking. Instead, when you insert the key into the AXA locking core on the right side of the frame and turn, the battery clicks down about half an inch, and you have to press a little plastic lever to fully release it. This second “release” step is great for safety but requires a bit of hand flexibility and some practice because the button is so small. If you’re wearing gloves, it could take a moment or be a little frustrating. And then, once pressed, the 7 lb battery comes dropping out and is almost as easy to drop as the Brose packs. Compared to the standard Bosch Powerpack battery design, the Powertube is heavier and has no handle to grasp when carrying. I’d probably leave the battery on the bike most of the time if I had room to store it near a plug and keep it away from extreme heat and cold… but I don’t, so battery removability is nice but also a point of vulnerability. These battery packs are not cheap but I’m guessing that the metal cover on the bottom is swappable between Powertube packs so you can keep the matching look. The included Bosch ebike battery charger is lightweight at ~1.7 lbs and very portable in size but also very fast at 4 Amps vs. 2 Amps on most standard electric bicycle chargers and even the cheaper Bosch travel charger. For such a high capacity battery, it’s nice to have a charger that’s stepped up. The one complaint I have about all of this is that on-bike charging positions the charger plug near the left crank arm which could lead to snags or bends if the pedals ever get turned backward or you trip over the cord. I guess there are always trade-offs to consider and I’m not sure the extra weight is worth the nicer appearance with the Powertube, especially now that some ebikes are sinking the older Powerpacks into the top of the downtube and using plastic covers to hide them. Think about traveling with your ebike… you could easily find a standard black Powerpack 400 or 500 at your destination, but will you be able to find a Powertube with the same cover plate? Or will you have to unscrew and bring this plate along to then re-mount? The Powertube looks nice but isn’t as lightweight, easy to cary, or easy to replace in my experience.
Navigating electric assist controls and menus on the SIX50 EVO AM 3 and 4 (and most of the 2018 BULLS Bosch ebikes) is done through the compact Bosch Purion display panel. I love how small and tough this display is, but it’s not removable, doesn’t have a functional Micro-USB charging port, and limits some of the menus on offer with the larger Bosch Intuvia display panel. For those with limited vision or a desire to upgrade, many ebike shops can help you to get an Intivia if you’re willing to pay more. With the Purion, you’ve got just four interaction points. Press the black power button along the top edge and it snaps to life quickly, showing your current speed, battery level, and assist level. Mirroring the power button on top is a black walk-mode button along the bottom edge. Once you’ve arrowed up into one of the four assist settings, you can press walk mode and then hold the plus button to have the bike slowly push itself… and this can be very handy if you’re walking a steep section of trail. Considering that even the small frame weighs ~55.5 lbs, and you might be wearing clip-in shoes, this could be a life saver. Or maybe you end up with a flat somehow? Same thing, and you can actually adjust the walk mode speed by shifting gears. The other two buttons are just plus and minus, and they let you cycle up from “off” to Eco, Tour, eMTB, and Turbo power mode. The higher you go, the more power the bike delivers, the faster it drains the battery, and the more noise it produces. I have become a big fan of the third level, eMTB, because it delivers a wide range of output based on how hard you pedal. For dynamic trail conditions, it allows you to focus on steering, shifting gears, and braking without thinking about the motor. And this motor controller is listening for your rear wheel speed, pedal cadence, and pedal torque over 1,000 times per second! It’s smooth, but a bit zippier in eMTB and Turbo than the Brose and Shimano systems in my experience. Coming back to the display, you can change from miles to kilometers by holding the minus key and pressing power, and you can activate the lights by holding the plus key. The display itself is always backlit with a dim white glow. If you hold the minus key, it will cycle the trip menu from odometer to trip distance, assist level and range estimate. I love the range menu because it provides more insight into how far you can go, with any of the four assist levels, than the simple five-bar battery infographic does. It actually uses your last mile of riding, the battery capacity, and the chosen assist setting to estimate realtime, and in my experience it’s pretty good! The one final standout with the Bosch motor controller and control system is that it listens for your pedal strokes and changes in chain tension to detect when you might be shifting gears, and then lets off with the motor a bit to reduce drivetrain wear. This is one feature that very few other companies even attempt, and while not perfect, it’s nice to have on a bike that will probably be climbing and pushing hard much of the time.
Closing thoughts… I love how balanced and well accessorized this electric bike is. It looks great with internally routed cables, black suspension stanchions, the integrated battery pack, and large plus sized tires. The brakes are great but both are 180 mm compared with the AM 4’s 203 mm front rotor and the 1×11 drivetrain is simple and durable but still wide enough for all sorts of riding, more than covering motor-supported speed. It’s always nice to have a pre-installed dropper seat post and I liked the ergonomic grips, even though this isn’t something I’m used to seeing stock on mountain bikes. They aren’t so fat or elongated that gloves feel weird or you cannot power-handle the bike. I don’t feel like anything was dumbed down on this “electric” mountain bike, the components, geometry, and drivetrain are upper mid-level. The price point feels right but I felt the battery charge port cover could have been improved for a better seal with easier connection, and that maybe it could be positioned further away from the left crank arm. It’s neat to see things like MonkeyLink on offer, because the connectors are pre-wired and that means the frame has to be designed for them… it’s not something you can add yourself aftermarket, if you want to leverage the main battery pack (MonkeyLink does make magnetic connectors for independently powered lights and fenders). As someone who enjoys trail riding with a bit of downhill mixed in, this bike was a blast to ride, it’s nice to have compression adjust to reduce bobbing when climbing or fooling around on trails and paved roads. It’s always nice to test mountain models on actual trail sections and I want to thank Bulls for partnering with me on this post, inviting me out and letting me get their new models dirty. And I want to thank my friend Ricky for filming and riding with me :D As always, feel free to post your own insights or questions in the comments below or in the BULLS bike forums here.
- Excellent weight distribution and stealth design, both the motor and battery pack are positioned low and center for improved handling and stability (no unnecessary weight is unsprung) and BULLS integrated the motor at an angle to blend with the downtube while opting for the Bosch Powertube hidden in-frame battery
- I was told that Bulls does not use the official split-pivot rear suspension design but it looks very close and provides the same sort of isolation and vertical travel vs. an arched movement which can change your chain tension and produce kickback… whatever it is, I like it
- Both suspension components are air which can be sagged to fit your body weight and ride style, they also offer compression and rebound adjust for improved climbing and descending performance, I like that the stickers match the fluorescent yellow accents on the frame even though the casings are black vs. metallic grey
- Since the rear suspension is vertical, there was enough room to squeeze in a downtube bottle cage mount and Bulls offers MonkeyLink accessory compatibility here (the magnetic bottle option is pretty neat and twists out to the side so the top tube on the bike can be low for reduced standover height)
- The stem and seat clamp are Monkey Link compatible which means you can add lights and fender accessories very easily… and then take them off quickly for storage or day/dry weather, it’s a great system that more e-bikes are using, I love how it runs the lights off of the main battery pack so you don’t have to use disposable cells or forget to turn them on/off when riding (hold the plus button on the control pad once on, to activate/de-activate the lights)
- This is a purpose-built electric bike with internally routed cabling that looks nice and as with many of the BULLS products, it is offered in three frame sizes which means you get a better fit
- Plus sized tires come in 2.6, 2.8, and 3.0 but the SIX50 EVO AM 3 has opted for the middle, more nimble, 2.8″ tire which still improves traction and float but handles quicker, Schwalbe makes some of the nicer tires in my experience and these ones come tubeless ready and use a new Addix soft compound for improved traction
- The Bosch Performance Line CX motor is extremely responsive, offers excellent torque, can detect shifting pressure changes and ease off to protect your drivetrain, and is said to be extremely reliable (by the shops that I visit when doing reviews)
- The Bosch CX motor does use more electricity and produce more noise because of the zip and torque on offer so I like that they went with the high-capacity Bosch Powerpack 500 and that you get the faster 4 Amp charger for faster turnaround time, the charger is lightweight, compact, and can charge the battery on or off the frame
- Excellent drivetrain here, the 1×11 design reduces weight and complexity vs. a double or triple chainring and you get a nice chainring guard up front to keep things on track and protect your pant leg, the Shimano Deore XT derailleur comes with a Shadow Plus one-way clutch to tighten the chain, further reducing chain slap and drops when set to the up position
- Gotta love the seat post dropper, this is critical for all-mountain riding where you transition from climbing to downhill and need elevation for pedal efficiency and then clearance for absorbing big hits and obstacles
- Excellent hydraulic disc brakes from Magura, you get quad piston calipers for even pressure and a larger surface area for cooling, larger 180 mm rotors provide a mechanical advantage and even more cooling for long descents, the brake levers offer adjustable reach which is nice considering the small and large frame options for riders with small and large hands
- Minor pro here, I like the skinny but still ergonomic grips that BULLS chose here, I usually upgrade my flat grips to ergo on electric mountain bikes because it reduces tingling in my wrists and hand cramping
- The Bosch CX motor comes stock now with eMTB mode which converts Sport level to a wide-range 120% to 300% assist, it acts more like a torque sensor and allows you to focus on handling and shifting vs. clicking to different support levels and it works surprisingly well… it’s consistent and doesn’t make you overwork or lag when stopping like pure torque sensors on some other models
- In order to support the plus sized tires, both wheels run Boost which is a wider hub spacing that provides a sturdier spoke bracing angle, I love the thru-axles for stiffness but noticed that neither one had quick release on this model so you’d need a hex wrench for trail maintenance and flat fixes
- I like that the BULLS electric bikes have walk mode enabled, it can really be useful for climbing a steep section of trail if you get off your bike (especially if you’re wearing clip-in shoes) or if you get a flat tire, just press the walk mode button on the lower edge of the Purion display and then hold plus to make it go
- The integrated Bosch Powertube batteries look great but they weigh more and are trickier to replace because of the frame-matched cover, compared to the external Powerpack 500 this thing is 0.35 lbs heavier and that’s without the metal shield portion! with that on, this battery weighs ~7 lbs vs. 5.8 on just the plastic Powerpack
- I test rode the small sized frame but even it weighed ~55.5 lbs which is on the heavier side for a premium full suspension model, I think the Powertube battery, all-mountain 150 mm suspension, and extra metal on frame reinforcement (at the bottom bracket and the little shield for the rear shock stanchion) add to this
- Be careful when lifting and transporting the Powertube battery because it does not have an integrated handle like the Powerpack mid-frame and rear-rack models, I do appreciate how it clicks down one step before completely coming off the bike, you are less likely to drop it when removing
- The Bosch Performance Line motors use a smaller chainring which rotates at 2.5x revolutions per crank revolution and this requires a reduction gear which produces some friction and drag, it’s not a lot but this can make pedaling unpowered less efficient than one-to-one chainrings from Yamaha, Shimano, Bulls, and even the Bosch Active Line, apparently the smaller ring provides an increase in chain grab and I suspect that it also provides a mechanical advantage to the motor
- In some ways, I’m not a huge fan of the Bosch Purion display panel because it’s not removable and doesn’t offer an active Micro-USB charging port the way that the larger Bosch Intuvia does… but some shops can upgrade this for you and frankly, for an electric mountain bike, the smaller display might stay out of the way and be less easily damaged, it works well enough but the button clicks can be inconsistent (press towards the screen vs. lower at the left, the buttons are hinged and click in towards the right… sometimes pressing the middle feels hard and just doesn’t click right)
- As much as I love the safety stop point on the battery (so it doesn’t just flop out when unlocked for removal) but you have to reach in and press this little plastic tab to release it fully and that could be a tight reach for people with larger hands and fingers, or if you’re wearing gloves
- If you do purchase a MonkeyLink compatible headlight, it doesn’t seem to be aimable up and down, it’s sort of fixed and based off of the mount alignment which could position the beam higher or lower than you really want
- If you charge the battery pack when mounted to the bike, there’s a little plug port on the left side near the bottom bracket… and the charging cable could get caught on the crank arms or even bent there… I also feel like the rubber cover is tricky to push in and just not super well sealed compared to some other ebikes, it’s probably fine but just didn’t seem as tough as I would like
- Official Site: http://www.bullsebikes.com/product/six50-evo-am-3/
- More Pictures: https://photos.app.goo.gl/ePiPcfLDRGYTehAx1