To run the forums, host the website, and travel, I charge a universal service fee for my reviews. This review was sponsored by BULLS. My goal is to be transparent and unbiased, this video and written review are not meant to be an endorsement of BULLS products.
Today we are looking at the BULLS E-Stream EVO AM 4 27.5 Plus. There is a lot in that name, so what is it exactly? Well the AM stands for all mountain, the 4 is the component level, this being the top of the line, and the 27.5 Plus is going to be the tire size. If you have read my review on the AM 3 version, there will be a lot of parallel information here. The two bikes are for the most part identical except for the component trim. The bike comes in 3 sizes (44cm, 49cm, and 54cm) and one color, matte black with these silver accents. It’s using the new Brose high power mid-drive system, the S Mag (sport magnesium), which is 15% lighter, is very responsive, quiet, and very fluid. A lot of people will compare this to the AM 3 which is $500 less (the AM 4 is $6,299). While you save $500, you do loose the Ergon grips, Magic Mary front tire, and having both front and rear brakes being quad piston, where as the AM 3 has only quad piston in the front and dual in the rear. As said before, here you have the Ergon locking grips. The front tire is a Magic Mary’s, but you will notice the rear has Nobby Nick’s tires. Both still 27.5 x 2.8 plus size, and they give you some great float and excellent grip. I think the difference for the two tire types on this bike is better climbing in the rear and better handling in the front. This full suspension here utilizes a FOX Rhythm setup with 150mm of travel and 36mm stanchions on both the front and the rear, so really great for descending or light downhill. They also both have compression adjustment and full lockout, air pressure settings, and rebound adjustment. Each suspension is coated in this this anodized surface, and the rear has a stanchion guard so that helps keep them protected from debris and looking good. Assisting the full suspension is this Kind SI 180mm dropper seat post which can be adjusted in real time, great for when you are switching terrain. Going back to the tires and wheels, I see a 15mm through axle in the front with some 14 gauge spokes and 110mm boost hub spacing which is a little wider so it provides a sturdier bracing angle. In the back it has 13 gage spokes with 148mm boost hub spacing, so again, the same benefit. I love how the quick release in the front has a little dial to adjust the positioning of the lever so you can really get it out of the way for your ride. Working our way to the handlebar, you notice it has a slight bend with a bit of a rise and a couple of spacers here so you can dial it in and make it more aggressive if you wanted. The stem is relatively short at 0 degrees and it has a steeper tube made for all mountain, so do be aware you really can’t adjust that tube angle. The seat is a Royal M1 BULLS branded saddle, which is pretty firm, maybe a little too firm for my personal taste, but still a very quality saddle. It looks like the bike has kickstand provisions that are out of the way of the crank arm, so that’s nice. I also wanted to mention the Monkey Link bottle option. Although $46 is a lot to pay for a bottle, it is very intelligent setup using this magnetic easy-on-easy-off type system. Also they have Monkey Link light provisions for both the front and rear. Again, these are magnetic and tap into the high capacity battery and is just a really clever setup. However, the cost to this is very high too, as the sight setup is an additional $170. I did notice if you get that rear light, you might want to be careful about dropping the seat post, it could come down and strike that. Overall the setup really balances comfort, performance, and reliability. I also need to mention the Velo slap guard, internally routed cables, and bottle cage bosses if you remove the Monkey Link provisions.
Driving the bike is a compact mid-motor from Brose called the Brose S Mag with redesigned casing that uses less material. It’s also using a lighter weight material; magnesium verses aluminum alloy. My guess is that the internals are similar to the Drive S Alu but the weight dropped from 7.5lbs to 6.39lbs. You still get a very narrow Q Factor, optimal spindle placement (to reduce chain stay length for snappier turns and a shorter overall frame length), and excellent ground clearance. This motor is compact and has a sturdy plastic skid plate below, in case you do take a rock or log strike with the suspension fully compressed on a drop. Note that the crank arms are 165mm vs. 170mm to reduce pedal strikes. So, the motor unit is small, but it really packs a punch. You get 250 to 560 watts of power output with up to 90 newton meters of torque! That’s extremely high for a mid-drive unit. Power is delivered based on your rear wheel speed, pedal cadence, and pedal pressure. The new Shuttle mode is all about torque, allowing you to raise it in lower cadence situations, sacrificing battery efficiency for more help if you prefer to pedal slow and reduce cardio while climbing. I personally love this feature because my knees are sensitive and I don’t always want to pedal fast. If, however, you do want to spin, the Brose motors all support 120+ pedal RPM. This means it won’t drop out on you while downshifting on approach to a big hill. Moreso than many other competing products, the Brose motor really hangs in there at high pedal speeds. The Drive S Mag is light, more powerful, and amazingly… more efficient than its predecessors, but it’s still quiet and smooth because it contains a Gates Carbon belt drive that transitions from gears to spindle output. This reduces vibration and provides an organic feeling to the pedal experience that I can vouch for. The older Drive S was my favorite between Bosch, Shimano, and Yamaha for this reason, and Brose is expanding its support and presence in North America. There’s no pedal drag if you do choose to pedal unassisted (no reduction gearing) and the motor is decoupled from pedal strokes beyond the maximum supported speed of 32km/h (20mph). It’s an outstanding drive system, but I do feel that the charging port positioning, on the left side of the motor bulge, requires additional bending over and is in the travel path of the left crank arm… which could get snagged or bumped out of position. At least it’s magnetic with a leash, so it won’t break, and the cover seems very durable. I should also mention this has ‘Flex mode’ which is a progressive pedal response that provides up to 30% more power as it receives input from the torque sensor to provide more power when you push hard vs. older systems that were more cadence based. This is a new feature, and at this point not a lot of information is available on it, so I will update the forums and new reviews as more information becomes available. Mechanically, the bike has a 36 tooth chain ring up front with a light weight guide. In the rear you have an 11-46 sprocket, so really nice and big with a great range for climbing. The derailleur is a Shimano XT Shadow Plus clutch, so you can tighten it or put it down for wheel maintenance or neighborhood riding. Stopping the bike are these lovely Magura hydraulic disc brakes. 203mm rotor in the front (so it is extra large and cools better) with quad pistons, and 180mm rotors in the rear also with quad pistons.
Powering the bike is a 37v 20ah lithium-ion battery pack. This battery is a big win here as it is really high capacity with that amp hour rating…. Its bringing in about 740 watt hours, so really just a great battery for all day riding. There is no battery cover here, but it does have this impressive aluminum alloy incasing that is actually IPX rated, so overall, very durable. The battery is about 8lbs and has this nice handle for transporting. There is also a battery readout infographic so you can check the charge level without putting it on the bike. The battery is secured via lock and key and it is using an Abus system that can be key-to-like with other Abus locks so you only have to carry around 1 key. I love the magnetic interface here for charging, very easy to use and clean setup. The charger itself has a magnetic cable too, and it is about 1.9lbs, so pretty portable. I love that it charges at 4.5amps…. That’s really fast and a great paring with this high capacity battery. To really care for this and other lithium-ion packs, I have heard that storing in a cool dry location vs. extreme heat or cold will extend the life and try to keep it about 50% full when not using for long periods so you won’t stress the cells. Try not to let it run down to zero, because that’s really hard on the cell chemistry.
Operating this BULLS bike feels simple because the display panel is compact and the main buttons are so intuitive. Once the battery is charged and mounted, you may begin by pressing the power button on top of the battery pack or on the top edge of the BLOKS control pad, which is located within reach of the left grip. This wakes it up, and shows your current speed in the middle, a battery bar infographic with five squares below, assist level with up to four full blocks above, and an up and down arrow with plus and minus symbols inside. To raise or lower motor support, you press onto the upper or lower half of the display itself. This fills in the blocks (which go from empty to four full) and that’s how you know what power level you’re riding in. Now, the readouts are off-white in color with the background being black. The readouts are fairly easy to see in bright light because the LCD is transflective. When you click in, the display will also become backlit for a moment, so it’s easy to see in dark riding conditions as well. The BLOKS display panel is definitely on the smaller side compared to Bosch, Yamaha, and Shimano. You don’t get any feedback about average speed, max speed, trip distance, or even odometer. The five 20% battery bars are much less precise than a full one-percentage increment readout and there’s no dynamic range estimator. Going back to the quiet motor and integrated battery design, perhaps this display will go unnoticed by fellow riders or be less provocative at the bike rack. You cannot easily remove it, nor can you swivel it once it’s tightened down. On the left edge of the control pad there’s also a walk mode button (which is useful if you get a flat or encounter a steep gnarly section of trail), along with a lights button. You can hold the lights button in for several seconds and then click up or down on the main screen to change units from miles to kilometers and back. Note that the light button is only really relevant if you purchase the aftermarket Monkey Link compatible lights.
All things considered, I really really enjoy the AM 4, its comfortable, has great performance, and that Brose S Mag motor is super super super quiet. There are some tradeoffs to consider though… some of them may be small, but small issues can add up so let’s see if they are livable for you. I noticed the charging port is positioned next to the crank arm so that could get in the way of the pedals, luckily though, the cord is magnetic, so if it gets pulled, it should remain mostly undamaged. I was a little surprised there was no USB port for charging to take advantage of that high capacity battery. Probably the biggest gripe would be having to buy the additional lights and bottle setup, $170 for the lights, and $46 for the bottle. This seems kind of high, especially since this bike is already at $6,299. If you do get that rear light, it is in the way of the dropper seat post, so that was also disappointing. However, the bike is really a stand out performer and these tradeoffs may seem trivial. I love the comfortable full suspension, the high capacity battery, and the quiet, powerful, lightweight motor. Backed with a 5 year frame warranty, 4 year warranty on the battery, 2 year on all other electrical components, and a dealer network, the BULLS E-Stream EVO AM 4 is a stand out performer. A big thank you to BULLS for having letting me try out the bikes on some beautiful trails.
As always, I welcome questions and feedback in the comment section below. Whether you own a previous version of the bike, have taken a test ride, or are brand new to the space, my goal is to provide an objective and honest resource. You can also join the BULLS Ebike forums and share your own photos, videos, and review updates to help others! Have fun out there, and ride safe :)
Pros:
- A full suspension all mountain bike with plus size tires, hydraulic disc brakes, high capacity battery, and a lightweight Brose S Mag mid-drive
- The Brose S Mag (sport magnesium) is 15% lighter, is very responsive, quiet, and very fluid, I enjoyed not only its capabilities at higher RPMs, but also it’s ability to work well in varying situations
- Great Magic Mary and Nobby Nick’s tires, 27.5 x 2.8 plus size, and they give you some great float and excellent grip
- The full suspension here utilizes a FOX setup with 150mm of travel and 36mm stanchions on both the front and the rear, so really great for descending or light downhill
- Both suspensions have compression adjustment and full lockout, air pressure settings, and rebound adjustment, each also is coated in this this anodized surface, and the rear has a stanchion guard so that helps keep them protected from debris and looking good
- I love the Kind SI 180mm dropper seat post which can be adjusted in real time, great for when you are switching terrain or riders
- I like the Monkey Link bottle option, it is very intelligent setup using this magnetic easy-on-easy-off type system, also they have Monkey Link light provisions for both the front and rear, again, these are magnetic and tap into the high capacity battery and is just a really clever setup
- Hydraulic brakes are a big preference for me, so I was happy to see a 203mm rotor in the front (so it is extra large and cools better) with quad pistons, and 180mm rotors in the rear also with quad pistons
- This 37v 20ah battery is a big win here as it is really high capacity with that amp hour rating, it’s bringing in about 740 watt hours, so really just a great battery for all day riding
- The battery is also housed in this aluminum alloy casing, so very durable and protected
- I love the Energy Bus Rosenburg magnetic charging system, the cables and ports are both magnetic so it makes attaching and detaching easy, while reducing damage from violent cord pulls
- The display is compact, out of the way, and very minimalist, definitely helps the stealthy feel of the lightweight Brose motor and integrated battery
Cons:
- Buyers may want to potentially opt for the AM 3 which is $500 less, but you do loose the Ergon grips, Magic Mary tires, and having both front and rear brakes being quad piston
- The seat is a Royal M1 BULLS branded saddle, which is pretty firm, maybe a little too firm for my personal taste, but still a very quality saddle
- Unfortunately, you have to buy the additional lights and bottle setup, $170 for the lights, and $46 for the bottle, this seems kind of high, especially since the bike is already at $6,299
- If you do get that rear light, you might want to be careful about dropping the seat post, it could come down and strike the top of it, something to be mindful of
- No USB charging here, it seems like a bit of a missed opportunity given that high capacity battery with a massive 20ah rating
- The display cannot be easily removed, nor can you swivel it once it’s tightened down, I like that it is small and out of the way, but some may prefer a larger screen
- I noticed the charging port is positioned next to the crank arm so that could get in the way of the pedals, luckily though, the cord is magnetic, so if it gets pulled, it should remain mostly undamaged
Resources:
ralph casciano
5 years agoi would appreciate your thoughts, comparing the 2018 vs. 2019 model, since the 2018 was your top rated bike.
ReplyCourt
5 years agoHi Ralph, to me, this is still a winning ebike and the small refinements make it even better. I like the battery charging port placement and cover upgrade as well as the Brose S Mag motor. It still looks great, comes in multiple sizes, and has the MonkeyLink stuff… it’s a great product that I would consider buying for myself.
ReplyJake
5 years agoCourt, I’m trying to decide between this bike and the Trek Powerfly LT 9.7, whats your take in their differences in how they perform? Thanks!
ReplyCourt
5 years agoHi Jake, that’s a tough call! I prefer the ride feel of the Brose S Mag, clean and lightweight battery integration of the BULLS E-STREAM EVO but trust Bosch quality more. Trek has more dealers and their stuff is all standardized. Since I usually only see brand new bikes, the BULLS seems awesome, but it might be worth considering how close a dealer is and reading up in the forums to see if anyone has some real world long term feedback about this. I have heard that the custom batteries that BULLS uses for their Brose models can get damaged more easily than Bosch if dropped, and it doesn’t have the two-step release system like PowerTube. Sorry for the slow reply here… I’d love your feedback someday whichever way you go.
ReplyJake
5 years agoCourt, I wound up buying the Trek Powerfly LT 9.7 for some of the same reasons you listed. Speaking to my local Bulls dealer he had some hesitance about being able to perform timely repairs on the Brose motor if needed, although he did find out that Brose just opened a facility now on the East Coast but hasn’t had to deal with them yet. He likened to the fact that the Bosch motor is almost bulletproof and repairs can be completed in a timely fashion. While I think the Bulls E Stream Evo has some better specs than the Trek, the Bulls wouldn’t have been available until their new models are released at the end of June and I am MTB-less right now so the decision was easy.
I also own a Trek Supercommuter + 8S and I am used to how the Bosch motor integrates with pedal input and while it’s not the smoothest sometimes, I’ve always found ample power. Most times, I ride in ECO mode but the one time I used Turbo to cross a busy intersection, I was blown away with the response and power. After taking the Powerfly out for an initial ride yesterday, I was very impressed with it’s overall performance, especially with the Bosch MTB mode, I’m very happy with my selection.
Thank you for your response.
Brian
5 years agoShould one be concerned that this bike uses a Nickel-Cadmium battery as opposed to Lithium Ion? I’ve read that because of a “memory effect”, a Nickel-Cadmium battery can experience a sudden drop in voltage, to the point in the charge cycle where the charging of the battery began. So the range of this bike with a 750-Watt Nickel-Cadmium could actually be a lot less that a bike with a Lithium Ion 500-Watt battery.
The other issue I’ve read is that Nickel-Cadmium batteries have a longer lifespan than Lithium-Ion batteries. Would you not buy the bike because of the Nickel-Cadmium batteries? Thanks for viewpoint!!
Brian
ReplyCourt
5 years agoHi Brian, I’d consider this battery pack on par with other high-end ebike systems. I have moved towards calling them all “lithium-ion” when in truth there is some variation in the type of battery chemistry out there, but not much. Most companies are pulling the same chemistry with slight variations for different sized cells like 188650 or the new 2700. I’m not a battery expert but perhaps this could be discussed in more detail in the help choosing an ebike section of the forums. I think that Ravi is a person who is very knowledgeable when it comes to batteries, look for him ;)
ReplyJohn
5 years agoThx a lot for pointing to the battery chemistry! But where did you find info about battery chemistry? I can not read from your picture. On USA page is not saying anything except capacity but on EU page is listed as “Lithium Ionen”. Brian is right, Nickel-Cadmium has memory effect. Not sure about Nickel Cobalt Aluminum. Court, could you please double check what kind of battery is actually used?
Tomasz
5 years agoI got Li-ion battery in mine estream AM4 2019 (EU).
ReplyCourt
5 years agoHi! My understanding is that most of these new battery types can be categorized as “Lithium-Ion” but some companies will go so far as to specify the exact chemistry of their cells. I think BULLS uses some of the highest end product out there, their packs for Brose ebikes are done by BMZ, along with the chargers, and they use the highest quality cells that last longer and are more reliable :) how have you liked your AM4 so far?! I just launched the 2020 review here, it’s very similar to last year, just a few little refinements.
Reply