BULLS E-STREAM EVO FS 3 27.5 Review

Bulls has delivered one of the most diverse electric mountain bike lineups to the US that I’ve seen to date. Their bikes come in multiple sizes, use the latest battery technology and feature premium components (in this case a Shimano Deore XT drivetrain with 22 speeds, Shimano M615 hydraulic disc brakes, Ergon locking grips and RockShox air suspension supporting burly thru-axles on both wheels, Boost technology that widens the hubs and Schwalbe tubeless ready tires). My focus as a reviewer goes from “is this bike capable” towards “how does this specific model fit in the lineup” given that they also have 29er models and speed pedelecs.

As a Class 1 ebike, you get a top speed of 20 mph and no throttle mode with the E-Stream EVO FS 3 27.5 but are thus allowed to use it on more trails. It’s an ebike that you have to pedal in order to activate and it relies on torque and cadence sensors to deliver smooth responsive power output. The bike doesn’t perform like some others I’ve tested where the motor is clearly on or off, this one feels more natural and is a lot quieter as shown in the video review above. With a nominal rating of 250 watts some may not be impressed at first but the peak out put of 530 delivers and I have never had an issue climbing, even the steepest trails, if I shifted down to lower climbing gears.

Powering the bike on can be a two step process if you haven’t ridden for a day, there’s a button on the top of the downtube that activates the battery and a second one on the display button pad. Once both are switched on you can choose from three power levels, offering increasing torque and speed… you can also click down to zero where the bike performs as a normal pedal-power bicycle would. At ~52 lbs this is not the worlds lightest electric bike but the battery capacity is enormous so you’re getting a lot of extra range in exchange. I found that the battery, motor and rear suspension weight was all kept as low and central as possible to maximize handling. My only grips are that the flap covering the charging port doesn’t stick down perfectly and might let some dust in over time and that the keyhole positions the key very near the left crank arm and could expose it to bending and breaking if left in.

With 27.5″ wheels and longer travel 150 mm suspension up front, I view this bike as an all-mountain model with the potential for enduro riding. Compared with the 29er models, these wheels are more agile and easier to turn. The tires are not super wide and thus, fit between ricks easier but might also sink into soft terrain and slip on angles easier. The tires are tubeless ready and feature Liteskin, meaning they have thinner sidewalls to reduce weight. One of the biggest benefits of this model compared with Bosch or Yamaha driven bikes is that the battery fits into the downtube and the motor is super quiet. This makes it much more invisible to fellow riders… and it makes hanging it on some car racks easier. If you’re looking to ride further and enjoy all types of terrain, not just flatter trails, then this would be an excellent choice. It does not have shift sensing so take care in how you ride and shift those gears, keep an eye on the key when messing with the battery (or just charge with it on the frame) and consider adding an independent cycle computer if you want more feedback. Also consider upgrading the pedals from the stock cages. Big thanks to Bulls for partnering with me for this review.

Pros:

• The battery and motor blend perfectly with the frame, from the side it almost doesn’t look like an electric bike at all and the motor runs very quietly so you can blend in
• Because it uses both a torque and cadence sensor, the bike responds fluidly as you pedal, it’s a great approach for mountain bikes especially because you might be riding on unstable terrain or paths that require quick changes in power output
• Despite having such an integrated battery design, you can still remove it easily for reduced weight, safer storage or charging separately and it just requires the key to do so… no extra tools
• I like the minimalist display panel they chose, it’s transflective so you can see it clearly in bright sunlight and it’s super small so it stays out of the way while not taking up too much bar space or standing out
• Bulls has chosen to use the EnergyBus charging port for the battery which uses magnets (like a MacBook) so if you trip over the cable it won’t bend the pins or tip the bike… it will just unplug
• Many of the Bulls electric bikes come in multiple sizes and the E-Stream EVO FS 3 27.5 is no different, you get three frame sizes to choose from to maximize fit and performance for your body type
• This bike would perform well on all-mountain terrain and possibly some nduro riding because it has a longer travel 150 mm suspension fork but mid-sized wheels with the popular 27.5″ diameter, it felt responsive but also forgiving to me
• This is one of the very few electric mountain bikes I’ve seen with more than 11 speeds, the Brose drive system allows you to have two chainrings vs. one so in this case, the Shimano Deore XT drivetrain delivers 22 speeds which is more like traditional unpowered mountain bikes but also increases weight and complexity a bit
• Solid 180 mm hydraulic disc brakes from Shimano, they deliver smooth powerful stopping that’s important for actual mountain biking, this bike can handle difficult terrain
• You get quick release on both wheels for faster, easier maintenance and convenient transport, both axles are thicker than normal with 15 mm in the front and 12 mm in the back
• It’s an excellent climber because of the mid-drive motor design (shift to lower gears to help it climb) and you should get you 40+ miles even on difficult steep terrain because of the larger battery pack
• Both wheels feature Boost which means the hub is wider or “longer” so the spokes don’t have to be so narrow, this improves strength and is useful for riding on bumpy terrain where big rocks or drops might come up, it also improves chain alignment
• I love that you can mount a water bottle cage on the downtube here and that the triangle space is left wide open because it makes hanging from certain kinds of car racks possible
• Most of the cables and wires are hidden, routed internally through the frame to reduce snags and stay out of the way while riding, this along with the nicer paint makes the bike look beautiful

Cons:

• I feel like the battery port flap (on the downtube) doesn’t stick into the frame as well as it could, I had to mess with it to get it to stay put and if you don’t take that extra time it might be easier for dirt or mud to get in there
• Be very careful with the keys when locking or unlocking the battery, the crank arms pass right by the keyhole and could bend the keys or get snagged if you leave them in, maybe future models will position this differently
• I’m not a huge fan of the cage style pedals, they get bent more easily and don’t offer as much surface area as a platforms like this, you may consider clip-in pedals but given the heavier weight of ebikes I have noticed that I sometimes unclip accidentally when tossing the bike around
• While the display is more stealth than a big screen, there aren’t as many readouts like max speed, trip distance or odometer and I don’t think Bulls has a smart phone app right now to let you dig in deeper and tune the bike, they went with simplicity here
• All mid-drive e-bikes tend to put more stress on the chain and sprockets and this one doesn’t offer shift-sensing so it’s up to you to shift smoothly to avoid mashing
• If you haven’t ridden the bike for a while the battery goes into sleep mode so you have to press power on the downtube and then again on the display panel, not a huge gripe but it’s an extra step and could make you wonder if the battery has gone dead or something if you forget and just go for the display
• Considering that the bike has 22 speeds and some of the gears lay the chain very close to teh chain stay, you might want to add a neoprene slap guard because the bike just comes with a basic clear sticker which will likely get banged up over time
• The weight of the battery, motor and even the rear suspension piston is kept as low as possible, it’s all very centered on the frame as well so you get maximum balance and handling

Resources:

• Official Site: http://www.bullsebikes.com/product/e-stream-evo-fs-3-27-5-3/
• More Pictures: https://goo.gl/photos/Vx7YDkCGfBZLHAfS7