2017 BULLS E-STREAM EVO FS 2 27.5 Plus Review

Bulls offers an extensive line of electric mountain bikes and the E-Stream EVO FS 2 27.5 Plus is their cross country model with 120 mm air suspension from SR Suntour. Actually, to me this is something of a cross country / trail hybrid because I’m used to seeing 80 to 100 mm travel for pure cross country. The longer travel and larger Plus sized tires offer a bit more comfort but you lose some efficiency. Given that it’s an e-bike, that’s not a huge deal… and the battery capacity on offer is impressive. This is an efficient electric bike in part because it uses a high-end mid-drive motor but also because you get remote lockout for the fork and a clicker lockout for for the rear. The linkage driven single pivot suspension design keeps cost low because it’s not proprietary and it provides space for a water bottle cage or accessory to mount on top of the downtube. Bulls is one of the few electric bike makers to provide this sort of provision and I love it. There are even holes on the left chainstay for adding a kickstand if you wanted! At just over $4k, this is one of the more affordable name brand, premium motor and battery, full suspension electric bikes I have tested. Many competing offerings are in the $4.5+ or $5k+ range and they don’t look as good. It’s available in two frame sizes so you can dial in fit and the color matching extends to both suspension elements and the saddle. Some unique accessories include the locking ergonomic grips, compact transflective control panel (with Micro-USB charging port for phones etc.), and magnetic EnergyBus charging connector. I love that you can charge the battery on or off the bike but have some grips about how it fits onto the frame. Overall, it’s an easy ebike to appreciate, one that’s relatively quiet but plenty powerful.

Powering the Bulls E-Stream EVO FS 2 is a compact, smooth, geared center-motor. Brose makes this unit and I’m always impressed with how well it fits onto a bike frame, it nearly fades away! The black casing matches the matte black frame on the E-Stream Evo perfectly and the two-chainring setup almost completely conceals it from the right. This is one of the blurry areas of the bike to me because you’d think that more gears are better right? But on an electric bike, especially one that offers 90 Newton meters of peak torque output and three modes of power… one that responds as quickly as the Brose does, do you really need so many pedal cadence options? Yes, this is a cross country electric bike which means that it’s designed to be pedaled more and possibly go further than a downhill bike. The gears let you interact more directly with the bike and use human power to move those 55 lbs of weight. But perhaps it would weigh less and require less maintenance with a 1×11 setup? The Brose motor is smart and fast but it doesn’t offer shift detection. That’s up to you to as a rider, definitely ease off as you shift in order to let the motor ease back as well. I do appreciate the higher end Shimano Deore XT rear derailleur with Shadow Plus one-way clutch. This little grey clutch lever lets you tighten the chain to reduce bounce on bumpy terrain. But the bike also has a slap guard to help, and the front derailleur clears debris and acts as a chain guide. This motor is quiet when it is new but I have heard some other models that had a sandy sound, just a bit rougher, and perhaps that’s due to heavy riding at demo events? There’s a carbon / rubber belt inside, much like you’d find in a car engine like a timing belt, and it’s durable but also smoother than gear-on-gear designs like Bosch which produce more of a humming noise.

Powering the bike, an efficient little display panel, and the Micro-USB charging port built into the base of said panel is a 37 volt 17.5 amp hour battery pack that I would describe as “very large” in terms of capacity. Most other batteries, like the Bosch Powerpack 500 only offer ~500 watt hours but you get 647.5 watt hours here! That’s a lot of juice and it means you can ride further or climb longer… but also more weight. About 1.5 lbs additional weight in fact. Add to that, the second derailleur and chainring and you can see why the bike is slightly heavier than competing models. I should be fair here though, this is a more application specific ebike, I don’t know of many other cross country models, very few have more than 11 gears, so in many ways the weight is just fine or even pretty good. This battery contains long lasting Lithium-ion cells, it’s protected by a foam sticker along the bottom, and the downtube mostly hides it from the sides. I like how it looks but feel that taking it off is a bit more difficult and precarious. There isn’t a clear handle to grab and since you pull down vs. lifting up, it seems easier to drop. Unlocking the pack is a two-step process where you insert a key and then pull a spring latch before the pack sort of drops down and then you pull it the rest of the way. When you put it back on the bike, you can click it in without locking it with the key. I feel like Bulls should have a spring lock so you always have to use the key to get it off the bike. It would be a bummer to forget to lock it and have someone steal the pack or accidentally bump the lever and drop the pack out the bottom. I also feel that the locking core is positioned dangerously close to the left crank arm and that the little rubber flap which covers the charging port (when the battery is mounted to the frame) does not seat easily or as tightly as most competing products. Who wants water, dust, or mud to get in there? I would probably leave the battery in the bike most of the time and just store the entire thing inside for safe keeping. The magnetic charging cord would be connected regularly and I love how easy it is to connect vs. pushing in or trying to line up, and if it gets tripped over there’s a lot less that can go wrong.

Operating the bike is very straightforward. You don’t have to press the power button on the battery to get it started like you used to. Now, that power button is more of an LED power indicator readout. To get the main display switched on, just press the little button along the top of the button pad (located near the left grip) and it bursts to life. Your current speed, battery charge level, and assist level are shown… and that’s it. You don’t get the additional stats like trip distance, average speed, max speed, or range estimate, but it also takes up less space. The display uses a transflective readout that looks great in harsh sunlight and even though it’s a bit further to reach with your left thumb, it’s intuitive to use. Just click up or down to increase or decrease power. You can feel it click, thank goodness, because the assist level indicator graphic is tiny. Four boxes communicate off, level 1, 2, or 3. I tested walk mode for the video review and noted that it works well but depends on the gear you choose to alter the walk speed. If you’re in a low gear, as I was, then walk mode is going to be very slow. The display panel is a great compromise in a world with lots of bulky, overdone, glaring screens… but it is not removable. I’ve already mentioned the Micro-USB charging port but it’s an awesome feature worth describing a bit more. A rubber cover (that seats well) keeps it clean and the port is situated just below the main button pad, if you plugged a smartphone or Garmin GPS device in, you could tap into that massive battery for longer use. Even a headlight or something fun like external speakers would work. I dislike wearing headphones while cycling because it’s dangerous to your surroundings (not hearing animals, cars, or other riders) and the sound of wind really disrupt the tunes. I don’t want to wreck the peace and tranquility for other riders but an electronic bell / speaker product like this could be a good way to get some tunes going safely when you’re riding alone.

I had a blast riding this bike on some access road terrain in Southern California and can easily overlook some of the inconveniences around the battery for how great it looks. Weight is well distributed and even though the Tektro brakes strike me as mid-level, the drivetrain is great. I’m used to seeing round flat grips vs. ergonomic but these were locking and rather thin so I think they would work well and provide a comfort boost on longer cross country rides. It’s neat to see an application specific electric bike here and the 27.5″ x 2.6″ tires performed great. They offered precision and quickness with a dash of comfort and traction. Thru-axles with quick release mean easy trail maintenance and transport. The solid 2+ year warranty, two frame size options, and extensive dealer network makes it easy to find, buy, and enjoy. Big thanks to Bulls for partnering with me on this review, meeting me on the trails, and allowing for some back to back rides. I got to compare different models and get a sense for how one geometry and hardware setup was different than the next. Please note that the suspension was not sagged for me and rode a little stiffer than it should have (especially the rear). This is the kind of setup that a shop could help you get right but I often have limited time and they set bikes up for heavier riders at demo events (I weigh 135 lbs).

Pros:

• The bike looks amazing, both the motor and battery are well hidden in the frame and blend perfectly with the matte black paint
• You can ride cross country or trail with this bike, the 120 mm travel is versatile and highly adjustable here, both shocks are air so they keep weight down and can be sagged to fit your body weight more precisely
• This is one of the very few mid-drive electric bikes with a high-end motor and more than 11 gears, you get a front and rear derailleur with a total of 20 gear combinations, this fits the cross country climbing and trail scenarios well
• Sturdy thru-axles on the front and rear wheels improve stiffness and support longer Boost hubs, the 2.6″ tires are at the low end of Plus size (2.6″, 2.8″, and 3.0″) so you save weight and get precision along with some float and bump deflection, another great choice for cross country and trail
• Available through a wide network of dealers so you can get help setting it up and keeping it running right, Bulls offers a solid 2 year comprehensive 5 year frame warranty on their products
• Two frame sizes allow you to find a proper fit and the $4.1k price point is pretty good for a full suspension model with mainstream drivetrain in my opinion
• The Brose motor is exceedingly quiet and smooth, it uses a Carbon belt drive to transition power internally and that dampens vibration
• Quick wheels and seat tube as well as a removable battery let you reduce weight and size for transport, I always take the battery off when hanging bikes on car racks and usually take at least one wheel off when putting it in the back of a station wagon
• I appreciate the color-matched suspension fork, rear shock, and saddle, I also like that you can mount a bottle cage on the downtube where the plastic battery casing extends up
• The Shimano Deore XT derailleur is pretty high up on the Shimano groupset offering and I like that it comes with Shadow Plus clutch here so you can tighten the chain for bumpy terrain (just push the grey lever up and towards the back of the bike to enable it)
• Powerful 180 mm Tektro hydraulic disc brakes perform well and keep weight down with a dual-piston setup on each caliper, the ergonomic grips lock in place and felt good, I also appreciate the threaded wire connectors (for strength and keeping water out)
• I like that the suspension fork has a remote lockout, there are provisions for mounting a kickstand on the left chainstay, you can turn the bike on directly from the button pad now vs. pressing the battery first, and the battery charging port cover fit a bit better than some of the other Bulls e-bikes I’ve tested
• The small transflective display panel stays out of the way and reduces clutter on the handle bars (especially important when you have two sets of shifters for the two derailleurs) and it even has a Micro-USB charging port built in to fill your phone or other portable electronic device
• Walk mode actually works on this electric bike, which is great considering that it’s ~55 lbs, just make sure you’re in one of the three levels of assist first and then hold the walk button, changing gears will make the bike walk faster or slower
• The Brose motor is incredibly quiet and responsive, it uses standard sized chainrings and just works well… at least the brand new ones do, I have heard some demo models with louder motors that might have been pushed harder? I owned one for over a year myself however and it stayed quiet

Cons:

• The suspension design appears to be Linkage Driven Single Pivot which is an open design (costing less than a licensed proprietary design) which does produce some braking feedback and isn’t as efficient for pedaling… although that’s less of an issue on an ebike, the rear shock does have lockout so that helps a lot, you may still experience some kickback when pedaling over fast bumps
• The bike’s a little heavy at ~55 lbs but that’s partially due to the high-capacity battery pack which weighs 7 lbs vs. 5.5 lbs on competing standard battery models and the Boost setup with larger tires
• Offering 90 Newton meters of torque, the Brose mid-drive is incredibly powerful for climbing but it doesn’t offer shift detection like Bosch, considering the dual-derailleur setup here, that could put more strain on the drivetrain and require more maintenance… at least it measures pedal torque so you can back off a bit as you shift to keep it smooth
• The locking core for the battery is very near the left crank arm, along with the charging port… it’s all a bit crowded and I wish the charging port cover seated more securely, at least the charging plug is magnetic so it can get popped out without causing damage if someone trips over the cord
• I love how the battery looks and appreciate the foam sticker underneath to prevent chips and scrapes but struggled to get the pack on and off since it seats up into the frame vs. down from the top, it’s not something you want to drop and it doesn’t have any handles or good gripping points like some other packs
• I’m getting pretty used to dropper seat posts on full suspension e-bikes but I guess in the cross country world, you don’t need it as much? Still, with 120 mm travel vs. 80 to 100 I could see trail riding with this and think a dropper could be worth having, consider the 30.9 mm Magura Vyron wireless dropper post for easy install and swapping between ebikes
• I like how simple the display is and feel that it shows the most important menus such as speed, battery capacity, and assist level… but it doesn’t show range, odometer, trip distance, clock, or any other useful stats like the larger displays do