2017 BULLS SIX50+ E FS 3 Review


Technical Specs & Ratings



SIX50+ E FS 3


Class 1


Full Suspension



Hydraulic Disc



482.4 Wh

482.4 Wh

52.5 lbs / 23.84 kgs



Frame Details

7005 Aluminium Alloy


Full Suspension


Rock Shox Deluxe RT Suspension, 150 mm Travel, Rebound Adjust, Compression Adjust, Boost 148 mm / 12 mm Thru Axle with Quick Release

Rock Shox Yari RC 29/27.5+ Suspension, 150 mm Travel, Compression Adjust, Rebound Adjust, Boost 110 mm / 15 mm Thru Axle with Quick Release

Bulls, Alloy, Double Wall, 35 mm Width, 32 Hole | Spokes: Stainless Steel, 14 Gauge Front, 13 Gauge Rear, Black with Nipples

Schwalbe Rocket Ron, 27.5" x 2.8", Performance, Folding, 17 to 38 PSI


Tapered 1-1/8" to 1-1/2"

STYX Alloy, 7° Rise, 31.8 mm Bore, Lengths: (60 mm, 70 mm)

STYX Alloy Low Rise, 740 mm Width, 25 mm Rise, 9° Bend, 31.8 mm Bore

Velo Rubber Ergonomic, Locking

STYX Aluminum Alloy


Selle Royale, Active

Wellgo C128DU Alloy Platform, Cage Style

Hydraulic Disc

Magura MT5 Storm Hydraulic Disc with 180 mm Rotors, 4 Piston Front Caliper 2 Piston Rear Caliper, Magura MT5 Levers with Adjustable Reach


Video Reviews

Written Reviews

The Bulls SIX50+ E FS 3 is a fun all-mountain ebike with Bosch CX drive system. It’s fun, because it can go almost anywhere with longer travel 150 mm suspension from RockShox and plus sized 2.8″ tires from Schwalbe. As a Class 1 electric bike with 20 mph top assisted speed, it would be allowed on more trails than Class 2 or 3 and I was able to pedal faster than this off-road due to in part to the larger wheel diameter. It coasts fast and rolls over obstacles with ease. Weighing in at about 52 lbs and offering three frame size choices, it’s a bike that can fit more riders and handles very well, it feels balanced. Most of the drive system weight is low and center where you want it, there’s limited unsprung weight. The wheels feel sturdy and stiff, even with larger tires, thanks to Boost hubs (slightly longer than average) and the 15 mm and 12 mm thru-axles. You get quick release on both wheels and the battery pack and display can also be taken off to reduce weight or store / charge separately. The motor is extremely responsive and powerful but does produce a whining noise at higher speeds, Bosch is known for offering higher than average max assisted cadence up to 120 RPM which means you can spin with lower gears and still get help from the motor… Some Yamaha systems by comparison, only assist up to 100 RPM. A highlight with the design of this bike is how the motor and battery are built into the downtube. The motor is angled up and blended into the frame with alloy plates extending to the base of the battery. Bosch drive systems aren’t as hidden or stealthy as Brose (which is available on some other Bulls models) but this one looks pretty good and the battery is going to be easier to remove, the battery interface is backward compatible with Bosch Powerpack 400. I also noticed that the battery could be locked and charged more easily than the Brose system and had a nicer rubber cover but there wasn’t room for a bottle cage mount in the central triangle of the frame.

Driving the bike is a 250 watt nominally rated Bosch mid-drive CX model that produces 75 Newton meters of peak torque output. It’s very impressive, don’t let the lower watt rating fool you… it peaks out above 500 watts and has been a top performer for me in climb tests, outperforming higher rated motors due to its responsiveness. Rather than spinning a standard sized chainring, Bosch systems use smaller rings (like the 15 Tooth ring here) that rotate at 2.5 times your pedal cadence. One limitation is that it does not currently support multiple chainrings and the smaller ring doesn’t get as much clearance over the right chainstay. This means the chain runs closer to the stay and can bounce into it on bumpy terrain. To address this, the SIX50+ E FS3 has a thin rubberized slap guard and is built with Shimano Deore XT Shadow+ drivetrain components. The Shadow+ model derailleur has a clutch system that can tighten the chain to reduce bouncing, slip and drops. And the chainring uses a narrow-wide tooth pattern and has an alloy bash guard (outer guide) to keep everything on track. Everything worked well during my ride tests across pavement, gravel and wood chips. Note that shifting requires a bit more effort when the Shadow Plus clutch has been engaged. The Bosch motor offers limited shift sensing that reduces mashing but you’ll still want to shift thoughtfully while easing off your pedaling a bit. The motor controller measures rear wheel speed, pedal cadence and pedal torque one thousand times per second to optimize response and shifting performance and as you ease off, the torque signal reduces motor power.

Powering this electric mountain bike is the new Bosch Powerpack 500 which fits the same dimensions and design as the older 400 watt hour pack and only weighs ~0.3 lbs more while delivering 25% more capacity for increased range. It’s an impressive battery that’s easy to mount, dismount, carry around and charge with the compact charger mentioned earlier. The left side of the case has a button with five LED ticks to indicate charge level which is useful if you’ve stored the bike in a garage or somewhere away from the pack and want to double check if it needs to be refilled before a ride. To maximize the life of this and other Lithium-ion batteries, you can store it in a cool, dry location. Bosch ships this battery at about 50% to avoid stressing the cells and that could be interpreted as a good way for you to store it for longer term periods between use… but avoid letting it get to and stay at 0%, I usually charge it up after a month or two of disuse and get it to 80% vs. 100% to avoid stressing the cells.

Operating the Bulls SIX50+ is very easy and quick. Once the battery is charged and mounted, you can hop on and ride around like a normal bike… then press the power button on the Bosch Intuvia display panel to boot it up and get assist. There are four power levels and I tend to ride in the second one (Tour) for a good mix of efficiency and support. The first level (Eco) is enough to reduce the struggle of pedaling a 52 lb bike around, making it feel like a normal 25 lb bike but it won’t do much for climbing or accelerating. Changing support levels can be done without removing either hand from the grips if the system has already been turned on. There’s a button pad near the left grip with up and down arrows that click as you press them. In between these buttons, an Information button is rounded and rubberized, creating a physical reference point. This button cycles through trip stats like max speed and trip distance but also shows range. Range is cool because it’s dynamically calculated using the last three miles of ride data, your battery level and the chosen assist level. For me, it’s much more useful than the five bar battery readout on the battery and display panel. The display is faintly backlit to make it readable at night but not so bright that it becomes distracting. It swivels to reduce glare and has a light bulb button near the lower right corner which isn’t used on this electric bicycle because lights have not been added. Depending on your local shop, integrated lights can be placed and they will run off the battery vs. independent cells. Note that you can enter into the display to change the clock, adjust shift recommendation and switch from miles per hour to kilometers per hour by holding the reset and i buttons on the display panel.

The Bulls SIX50+ E FS 3 is a go-anywhere machine that’s nimble and beautiful. I love the battery and motor integration and appreciate the upgraded Selle Royale saddle, Magura hydraulic brakes and ergonomic locking grips. While I do wish it came with a seat post dropper, the quick release seat tube collar does the trick with a little more time. Bulls has a great reputation in Europe and has entered the US without missing a beat. Their bikes aim to balance value with high quality hardware, dealer support and a solid warranty. The terrain I tested this model on does not do it justice but I still had a blast. It’s easy to reach and maintain 20 mph on rolling terrain and even moderate inclines but going faster is no problem on flats and downhill thanks to the larger tires which almost ride like 29ers. Big thanks to Bulls for partnering with me on this post and taking me out to a few neat spots near their US headquarters in Los Angeles.


  • Tight motor integration, older Bosch Centerdrive motors bulged out in the front and hung down lower, this one is angled and tucked up into the downtube raising clearance and blending in nicely
  • The battery pack looks great as well, the base is cupped by an Aluminum flange that extends towards the motor and stickers connect the two sections visually
  • Longer Boost hubs support plus sized 2.8″ tires which provide stability and improved traction, they’re a blast for trail riding and push the effective diameter of the 27.5″ rating closer to 29″ which improves speed and allows you to roll over large obstacles
  • Three frame sizes available so you can dial in fit, angled top tube lowers stand over height so mounting and dismounting is safer
  • Stiff thru-axles offer strength and support the wider, heavier tires, you also get quick release on both so trail maintenance and transport is faster and easier
  • Both the display and battery pack are removable which takes the bike weight down to ~47 lbs for easier transport on car racks (especially useful if you’re moving several bikes at once)
  • Micro USB port on the right edge of the Bosch Intuvia display panel can run some electronic devices or help charge a bright headlight for dusk or trail rides
  • Air suspension is more adjustable and lighter weight than coil, both are long-travel with compression and rebound adjust as you’d expect from higher end components
  • Compared with the Brose powered Bulls models I feel like the battery pack is easier to charge and the charging port is better protected, taking the pack off also feels safer because it’s lighter weight and has a handle loop at the top
  • The increased torque of the Bosch CX motor combined with trail riding means the chain, sprockets and derailleur may take more abuse even though the motor has software driven shift-sensing, to help keep the chain on track and reduce bouncing and slipping you can activate the one-way clutch on the Shimano Deore XT Shadow Plus (the grey lever that pulls back)
  • The chainring features Narrow-Wide teeth to lock onto the chain better and reduce slipping and kickback (since this has rear suspension), it pairs nicely with the Shadow+ clutch system
  • Excellent weight distribution with the motor and battery mounted low and center, the motor responds very quickly and offers incredible power for climbing with 75 Newton meters peak out put
  • Older Bosch systems used a 400 watt hour pack but this bike comes with the 25% larger Powerpack 500, you can easily bring the charger to extend rides further because it’s compact,
    relatively light weight and faster than average, putting out 4 Amps vs. 2 Amps on other systems
  • Nice grips, they’re narrow like standard mountain bike grips so you can wear gloves and really control the bar but they offer some ergonomic support and are locking but light weight (the locking screw is under the ergo wedge vs. an end cap)
  • Quality hydraulic brakes with four piston caliper in the front to improve power and distribute heat, both rotors are 180 mm and the levers are adjustable for reach
  • Given the smaller 15 tooth chainring on this and other Bosch powered full suspension mountain bikes, I was surprised that they didn’t put a pulley in to reduce slapping and kickback, I didn’t have any issues during my test ride and they do include a slap guard but it’s an area for consideration
  • Internally routed cables keep the frame clean and reduce the potential for snags and scratches, I like that the top tube is completely clean for transporting with hang style racks
  • The chain is kept on track by the NW sprocket and a bash guard / protector which also keeps pants clear… but who mountain bikes with baggy pants O_o


  • The Bosch CX motor is a bit louder than Brose, you can hear a signature whining noise when it operates at high RPM, it’s also limited to a single chainring at this time
  • No seat post dropper here, the combination of longer travel and larger wheel diameter means all-mountain to me and droppers can be really useful for that kind of terrain variety, they cost a bit if you want hidden wiring but there are also cheaper ones too (get the 30.9 mm diameter to fit this ebike)
  • No bottle cage bosses, very few of the Bosch powered full suspension ebikes have managed to fit these because the triangle space is limited (especially on the smaller frame sizes)
  • If and when you need to replace the battery pack, it won’t necessarily come with the same matching decals and I’m not sure how easy transferring them would be, it might not look as good then
  • The stock pedals are lame in my opinion, they are cheap alloy cage style platform pedals that are easily bent up and don’t offer the surface area or traction I prefer for trail riding like this

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