2017 BULLS E-STREAM EVO FS 3 27.5 Plus Review

Plus sized tires are becoming increasingly popular for electric bikes. That’s because they improve comfort a bit, increase your contact patch size resulting in better traction and they disperse some of the added weight that a motor and battery produce on the frame. I suppose they would have become popular more quickly with traditional pedal-powered mountain bikes except for the added drag and weight. With an e-bike, you’ve got electric assistance that more than compensates for a bit of drag and thus, more bikes are turning to these tires as a sweet spot between 2.25″ and the much larger 4″ fat tires often reserved for sand or snow riding. With the E-Stream EVO FS 3 27.5 Plus you get 2.8″ wide plus sized tires whereas some competing bikes are opting for full 3″. I found these to perform similarly, perhaps they’re slightly lighter due to the lower volume of rubber? Another unique quality of the wheels on this bike are that the hubs use Boost technology which is to say, they are slightly longer. This allows for steeper spoke angles and a stronger more sturdy wheel as a whole.

Okay, with all of that tire and wheel stuff behind us, let’s chat about the drive system a bit. One of the coolest aspects of the Brose powered models from BULLS this year is that the battery pack and motor are extremely tightly integrated… nearly disappearing into the frame. This is a beautiful looking, well balanced and QUIET electric bicycle designed to Class 1 specifications, meaning it only assists up to 20 mph and does not offer a throttle. In many parts of California, that means you can legally ride it on mountain bike paths. It’s perceived as a human powered cycle first because it uses a combination of wheel speed, cadence and most importantly, pedal torque activated operation. Laws aside, what I found was a super-responsive mountain bike that felt comfortable even when riding near steep cliffs, as I did in the video review above. In this type of terrain, you don’t want a clunky or slow-to-react drive system because it could take you past the mark resulting in an accident.

The Brose motor used here offers a whopping 90 Nm of peak torque and a range of 250 to 530 watts power output. At high cadence, you can hear a pronounced electronic whirring noise but I’d consider it one of the quietest mid-drive systems on the market right now. This is due in large part to the addition of a belt link inside the motor case that reduces vibration. I’m only guessing but this might help to extend the life of conversion gears and as a rider, it does create a smoother feel than say, Bosch. Now, I’m a huge fan of Bosch and BULLS offers this drive system on many of their other mountain models… but it’s a lot zippier and the chainring is limited to just one sprocket. A huge differentiator with the Brose motor is that multiple chainrings can be used and in the case of the EVO FS 3 Plus, they opted for an 11 ring cluster in the rear with two rings up front. The shifter and derailleur hardware is higher-end Shimano Deore XT Shadow Plus and although the motor does not offer shift sensing, I had no problem shifting without much mashing when I adjusted my shifting behavior a bit… making sure to ease off the torque pressure and thus, deactivating the motor before shifting.

This is a really fun and capable all-mountain electric bike. It has longer handle bars (as it should) locking Ergon grips for stability, a four-bar link suspension with quality RockShox components and the’ve even managed to squeeze in a bottle cage mount. One thing I’m not super fond of is how the battery pack locks in and charges on the bike. While I love that Bulls opted for the EnergyBus magnetic charging interface (that reduces bent pins and tipped bikes if tripped over) I don’t like the little rubber cover that’s used on the frame. It can be difficult to force into the charging port hole when not in use and I just feel like more dust and water will get in as a result. Also, you have to manually lock the battery in after clicking it onto the frame. It’s like a two step process where you use a keyed slot for locking the battery and a separate slider rod for disconnecting and taking off the pack. Perhaps this was intentional as twisting a key while holding a battery requires more finesse vs. sliding a rod while holding a battery… but in both cases you need to be extra careful not to drop the battery and in the former, if you leave your key in and forget, then later move the bike backwards the left crank arm may collide with and bend the key! It’s all just a little cramped and tedious. But at least it looks good, secures the battery properly and I like that they included foam pads on both the motor casing and battery case base to deflect rocks and other debris.

Having used this bike a bit on true mountain terrain as well as the popular Specialized Turbo Levo which also uses the Brose motor and has plus sized tires… I must say I enjoyed both. Priced at $4,699 I find the Bulls option to be quite tempting. And although they are somewhat new to the US market, their reputation in Europe and Asia is good and their warranty is reassuring. You get two years comprehensive and they are opening more and more dealers each year. My final thought is that it’s great to have a wider range of size options on this and other e-mountain bikes. This thing isn’t super light at ~54 lbs, nor is any other full suspension higher capacity build. Not having to worry about a frame that doesn’t fit or one with an unnecessarily high stand over height is nice. I appreciate the sloped top tube here and the overall stability of the geometry. Most of all, I just think it looks great. Big thanks to Bulls for partnering with me for this review.

Pros:

• Available in four frame sizes for improved fit and comfort on longer rides, the top tube is angled as much as possible while still affording a vertical rear shock (lower weight distribution along with the battery and motor)
• The electronics on this bike are extremely well integrated and hidden, the battery mounts up into the downtube, the motor completely replaces the bottom bracket with a custom interface and even the display panel is small and unobtrusive (just a toggle switch with little readouts) most wires are internally routed across the frame
• The slightly larger 2.8″ wide tires offer more cushion, better traction and less deflection which makes them fun to ride on trails and mountainous terrain, the Schwalbe Rocket Ron model is designed with thinner sidewalls to reduce weight and are tubeless ready for further reduction while also permitting low PSI without “snake bite” tube punctures
• Amazingly, despite the main triangle being mostly occupied by the rear suspension and tighter area due to the sloped top tube you are able to mount a bottle cage or other accessory using the bolts on top of the battery
• Longer travel 150 mm suspension fork and 15 mm thru-axle makes this a great candidate for enduro and all-mountain riding, the rear 150 mm suspension is also solid with some adjustability on stiffness and you get a 12 mm axle there… both are quick release for easier maintenance and transportability
• You get 22 gear combinations here with quality Shimano Deore XT Shadow Plus components, if you’re climbing a lot this comes in handy and the E-Stream EVO FS 3 27.5 Plus is one of the few mid-drive full suspension ebikes I’m aware of with that many gears
• The Brose motor is very quiet and smooth thanks to a belt interface between the gearing parts that reduces vibration… I also found that it was responsive and quite powerful
• I appreciate the upgraded touch points including locking Ergon grips and comfortable Selle Royal Seta M1 saddle
• MT-4 and MT-5 hydraulic disc brake calipers from Magura (two and four piston models respectively) offer great stopping power, both rotors are 180 mm diameter for dispersing heat
• The wheels are built with “Boost” which means they have longer hubs that allow for a stronger spoke angle and stiffer handling
• Both the battery and motor casing have a layer of foam padding on the base for protection against rocks and gravel flying up as you ride, it’s not as tuff as some other BULLS ebikes with metal scuff plates but also doesn’t weigh as much
• Despite being so small and compact, the toggle button / display panel thing near the left grip has a built in Micro USB charging port so you can power your phone or other portable electronic device!
• Impressive two year comprehensive warranty, 1,000 full cycles on the battery and five years on the frame… this is a larger more established company with good support

Cons:

• Be extra careful when keys are inserted into the battery lock as they are directly in the path of the left crank arm (which rotates backwards if you roll the bike backwards)
• The battery comes out downwards from the downtube and while it’s secure once unlocked, if you’re pulling down to remove it there’s a bit more force at play due to gravity and that makes it easier to drop or mishandle
• This is one of the only bike designs I’ve seen with a battery that can be clicked onto the bike but not locked (you have to purposefully lock the core using the keys), a secondary slide mechanism unclips the pack
• I feel like the rubber flap covering the charging port on the lower left are of the downtube could work better, it doesn’t fit into the charging hole very easily and this means dust and water can get in
• There’s no shift sensing technology on the electric bike drive system and considering you get 22 gear combinations, that means you’ll have to be extra thoughtful about how and when you shift, it’s torque sensing so just get up to speed then ease off while shifting before applying more pressure
• I’m not sure this bike comes with a slap guard? Consider adding a neoprene wrap or sticker (even clear tape) to avoid chips on the right chain stay
• Good combination of rolling momentum and quick handling with the 27.5″ wheel size here, I’ve found that they also don’t clip my toes as much as 29ers
• Given the longer travel suspension I was surprised that they didn’t add a remote seat post dropper, this kind of thing is very handy when you start to do more downhill riding and the bike is priced pretty high so it would have been nice if it was included, here’s a solid dropper that would fit the 30.9 mm diameter of the bike for consideration