BULLS E-STREAM EVO FS Enduro 27.5 Review

The Bulls E-Stream Enduro is a downhill oriented electric bike utilizing the highly-integrated Brose mid-drive motor system. While it’s positioned as top of the line, you might also consider the FS 3 which offers the same 27.5″ wheel size and 160 mm travel with less aggressive rake. This translates to cross country riding vs. enduro which is a racing style that includes uphill climbs and steeper “downhill” descents. I demoed the Enduro model at an Electric Bike Expo event in Denver Colorado and was able to cruise around the parking lot, take on some rocks and climb/drop a steep grassy outcropping. Not exactly true enduro riding but it offered some time with the bike and reps to get to know the systems. In my opinion the Bulls Enduro performed great and reminded me of the Specialized Turbo Levo models which also use a trail tuned Brose centerdrive. The big differences were frame geometry, narrower 2.35″ tires vs. 3″ on the Levo, a more traditional bar mounted LCD button pad combo vs. downtube mounted buttons and an LED light readout on the Levo and a fixed non-removable battery on the Bulls. I liked the LCD display (especially with its transflective easy to read technology) but didn’t hear anything about an app so there were definitely gaps in the information being offered by the bike (like odometer, trip meter, range estimate). The biggest trade was having a fixed battery… I didn’t get to weigh it directly but at ~7 lbs this makes the overall frame heavier during transport and limits your charging options. You basically have to bring the entire bike inside or near an outlet to fill it up. And if you decide to leave it in your garage in hot summer months or cold winter ones the cells might degrade more rapidly than if the pack was kept separate in a cool dry location.

Performance wise, the bike rides great with high end components from RockShox and Shimano. I especially like the hydraulic disc brakes with quad piston pads and integrated heat sinks… This is important for actual downhill riding, especially given the heavier build of the bike vs. a carbon fiber non-electric. Depending on where you live, Class 1 ebikes like this (offering pedal assist only, up to 20 mph) may or may not be allowed on trails. In my experience, regardless of laws, the less noticeable your bike is the more accepted you’ll be and judged on behavior vs. hardware. When I first tested the Brose mid-drive in 2015 I had some complaints around lack of shift sensing but the compact design and quiet operation have since won me over. Unless you’re spinning at a high speed, the motor is very quiet and almost completely obscured behind the 38 tooth chainring. I love that Bulls has included an e*thirteen chain guide to clear mud and reduce drops (and possibly chain slip) but was surprised that the demo model I tested only had 10 sprockets vs. 11 listed on their website. 2015/2016 is their first year selling this and other models in the US. With a two year motor/battery warranty and five on the frame AND a longer history of operation in Europe (the company is German), parts of Asia and Australia, I felt that the quality of the components and build would also be reflected by good support. One area of opportunity, aside from battery removability, might be wire management. As it stands, wires are run along the top of the downtube vs. internally and you may or may not be able to add a bottle cage here which would be nice.

Pros:

• Extremely stealthy, the battery pack is integrated into a slightly larger downtube and the motor takes up the bottom bracket space without being oblong or extending much beyond the chainring, the bike could go unnoticed more than some other mid-drives like Bosch or Yamaha
• Smooth and quiet, at lower RPM levels the motor hardly makes a sound, I did hear it pick up when I shifted way down and began spinning but otherwise it was one of the quietest ebike systems around (for this and other Brose powered bikes)
• The motor relies on cadence and torque sensing for activation so if you push harder you get more back and it’s not as on/off feeling as Bosch, in some cases it feels less powerful but the 90 Nm torque rating is pretty impressive and it climbed well for me in lower gears, it’s responsive so the chainring stops spinning quickly after you stop pedaling (no brake lever motor inhibitors required here)
• I love the display system used here, it’s small but easy to read with a special “transflective” LCD readout showing your speed, assist level (1-3) and battery capacity
• An aftermarket chainguide was added to clear debris and keep the chain on track, it looks like a TRS or TRS+ model from e*thirteen
• Durable battery integration, BULLS says it’s rated at the battery is rated at IP56 against water and dirt which isn’t as high as the Specialized Turbo offering IP67 (using the same drive system) but still better than no rating at all
• Tight tolerance on the battery pack alignment and locking system, you don’t hear it rattling around at higher speeds off-road but you also can’t easily take the pack out so this makes sense
• It’s available in two frame sizes to improve fit (43 cm and 46 cm) but only one color scheme and only in high-step (but the top tube is more angled so stand-over isn’t extreme)
• Excellent weight distribution, the motor and battery (which make up at least 14 lbs) are both mounted about as low and centered as possible since they’re integrated into the frame design
• For a full suspension electric bike with 36 volt 14 amp hour battery this thing is fairly light at ~50 lbs, you should get solid range due to mid-drive efficiencies if you shift properly and use the first two levels of assist
• Great Shimano Saint hydraulic brake setup with extra large 203 mm front rotor and heat-sink calipers designed to deliver consistent stopping power even in long downhill situations
• The tires come tubeless ready so you can set them up to ride at lower pressure and avoid pinch flats, Schwalbe Hans Dampf offer durability and the 27.5 wheel size is a nice trade-off for downhill and cross country riding… in my opinion this isn’t a true downhill-only ebike and I like that it’s a bit more versatile vs. something like the Haibike XDURO DWNHLL Pro
• Aggressive fork angle and enduro geometry with long travel 160 mm suspension so you can take bigger hits when descending rough terrain
• Thru-axles on both wheels with quick release so you can perform trail maintenance more easily or reduce weight/size for transport (15 mm front and 12 mm rear), the axles also help you line up disc brakes more easily and provide stiffness when riding off-road
• I like that the display kind of clicks so you can get feedback even if you’re not looking down at it while adjusting, it’s easy to reach and there’s a built in Micro USB charging port for maintaining your phone or other portable electronic device

Cons:

• The Battery is not easily removable, you have to unscrew bolts to get it off verses just using a key or tool release system like with most other ebikes (including the Specialized Turbo LEVO which uses the same drive system from Brose) this means you have to bring the whole bike near an outlet to charge it and may end up exposing the bike+batteries to hotter and colder temperatures in a garage which isn’t as good for them
• The display looks great and is easy to use with a tactile click up or down but isn’t large enough to show Odometer, Trip distance and some other sub menus like estimated range that appear on Impulse, Bosch and other systems with large consoles
• Offers 10 gears vs. 11 or even 20 on some of the other mid-drive systems, there’s only one chainring to reduce weight, drops and complexity… I know the website says 11 but the bike I tested only had 10
• While some of the other Brose powered ebikes have smart phone apps to help approximate range based on battery capacity remaining or your heart rate and even use GPS the Brose Enduro does not seem to offer one at this time, thankfully it has the basic readouts covered with a small LCD display
• There’s no shift sensing built into the software or hardware (shift cables) as I’ve found on Bosch and Impulse drive systems, this could lead to more chain, sprocket and derailleur wear unless you’re conscious about how you ride (ease off when shifting gears, especially in the two high levels of assist)
• The included battery charger is very fast but also a bit large and heavy making it less pleasant to stow in your pack, I like that it uses a magnetic Energy Bus interface
• Quite a few of the cables and wires are exposed on top of the downtube, I saw a bunch of bolt heads towars the bottom where it meets up with the motor and seat tube and believe you might be able to mount a water bottle cage there which would be nice but am not completely sure
• some of the specs recorded on the website were inconsistent with what I saw in person, most notably they said it was an 11 speed but I counted the sprockets at 10 on the demo bike
• When you pedal really fast at a high cadence the motor produces a more noticeable kind of scratchy sound, most of the riding I did was very quiet however

Resources:

• Official Site: http://www.bullsebikes.com/product/e-stream-evo-fs-enduro-27-5/
• More Pictures: https://goo.gl/photos/Ufeo9DjEFigVkw1g9