BULLS ADVENTURE EVO AM 27.5 Review

This review was provided for free, but BULLS and Cit-E-Cycles supplied a temporary demo bike for me to test. My goal is to be transparent and unbiased with you, this video and writeup are not meant to be an endorsement of BULLS products. I welcome your corrections, additions, and feedback in the comments below, and the BULLS electric bike forums.

Observations:

• The Bosch Performance Line CX offers great power, sensitivity to shifting, and is smaller and lighter than ever, but it’s louder and more power hungry than the rest of the line. Having two batteries on this ebike greatly extends the range, but also adds weight. The top battery raises the center of gravity on the frame and required a more aggressive top tube to fit, which significantly raises the effective standover height and may introduce dismount hazard in unstable mountainous terrain. Still, compared to many other dual battery full suspension ebikes (cross country, trail, or otherwise) the suspension design and handling are quite good.
• BULLS is a German ebike brand that was formed as a cooperative with dealers. To me, their products offer great value without cheaping out on components, aesthetics, and frame size options. While this particular ebike is not inexpensive, it delivers higher end hardware from respected companies like Bosch, Fox, Magura, and Shimano. BULLS offers customers a way to see, touch, test ride, and get service for their products in Europe, the US, and Canada through their extensive dealer network, which gets priced into the bikes. For a fancier, potentially higher maintenance product like this, I see that as a strong benefit.
• There aren’t many trail capable dual battery full suspension ebikes out there right now. Having covered the Riese & Müller Delite in several forms, including the Delite Mountain, I rank the BULLS Adventure EVO AM 27.5 higher for actual mountain biking. The four bar Horst link rear suspension isolates control and handling from braking and pedaling movement. By comparison, the Delite models use a slower swing arm rear suspension with higher unsprung weight and more horizontal chain movement. This can cause kickback in the chain, especially with smaller chainrings, slower suspension response, and less effective stopping from my experience.

Pros:

• This is one of just a handful of dual battery full suspension ebikes available on the market right now, especially in multiple sizes! The bike comes in four sizes and features two high capacity battery packs that offer ~1125 watt hours of capacity. I appreciate that they chose the lighter more compact PowerPack 500 for the top battery, so the top tube could be more sloped to make the bike easier to stand over (even if it still is a bit tall).
• The bike costs a lot, but BULLS really delivered with premium components from Shimano, Magura, Bosch, and Fox. Both suspension elements are air vs. spring, so they’re lighter and more adjustable. Both the suspension fork and rear shock have black anodized stanchions to match the look of the bike and they offer compression and rebound adjust.
• I’m a fan of plus sized tires, especially on electric bikes. They provide traction, stability, and tend to be more forgiving than medium width 29ers. These 27.5″ x 2.8″ Schwalbe tires were hand picked to suite this bike and the front uses softer rubber and a wider deeper tread pattern than the rear, which improves steering. Both tires come tubeless ready (for running lower air pressure and reducing weight).
• To accommodate the wheels, both axles are a bit wider (Boost hub spacing). This allows the spokes to get a sturdier bracing angle. Note that the rear spokes are thicker 13 gauge (vs. 14 at the front), to add strength. Both wheels are custom with assymmetric layout to accommodate the large cassette and Boost bottom bracket spacing. Finally, the thicker thru-axles (15mm up front and 12mm in the rear) improve stiffness and overall strength.
• Given that the bike is wider and heavier, I love that BULLS includes an 18mm kickstand mount towards the back of the left chainstay. I added one of my own aftermarket kickstands to help steady the bike for this review (you can get a compatible kickstand here), which made it easier to interact with the batteries.
• The Limotech dropper seatpost for this bike comes in three sizes, and is matched to the size of the bike you choose. It’s a necessary and useful part on this all mountain electric bike because of the taller top tube (due to the extra battery mounted below). The dropper worked great during my test rides and matches the black accents beautifully.
• I love that they used a lightweight generic battery cover for the PowerTube 625 and not metal. This decidion saved weight, money, and makes it easier to swap out any “naked” PowerTube 625 from shops or friends. Some of the older BULLS models used an aluminum alloy cover that looked beautiful but was much less practical.
• If you decide to ride without the PowerPack 500, to save weight, there’s a rubber plug that protects the battery interface where the top tube and head tube meet. Great attention to detail here!
• I love that BULLS has positioned the locking cylinder for the PowerTube 625 and the charging port up high on the right side of the bike. Both batteries can be charged simultaneously from this single port when they are mounted to the bike… otherwise, you’ll need to plug each one in separately.
• This ebike comes with the faster Bosch 4 amp standard charger! It makes perfect sense, given that it ships with two high capacity battery packs. In general, I like this charger because it’s fairly compact, lightweight, and quiet compared to almost all of the competition.
• You get a Bosch Kiox display here, which is awesome because it has a built-in Micro USB charging port! This allows you to charge or maintain portable electronic devices while riding! It’s a great feature, given how much battery capacity this bike offers. The display has a durable Gorilla Glass screen, is magnetically attached (for easy removal when parking or if you crash hard), and shows a color light-adapting screen with lots of menus.
• In addition to the great number of screens on the Kiox, Bosch also has a smartphone app that offers a GPS map utility as well as some tuning features. I love the default readings on the Kiox however, as they provide more than most of the competitors in the space including pedal stroke RPM, battery charge level percentage (for both packs separately!), and calories burned, and heart rate (with optional heart rate monitor connected).
• The fourth generation Bosch Performance Line CX motor really impressed me in terms of power, drive modes, shift detection, high pedal speed support (over 120 RPM), and reduced noise. Many of the older CX models made a high pitched whining noise, but this one was very quiet. The 4th generation CX is also very compact and lightweight at just 6.3lbs vs. 8.8lbs before, in part due to the reduced physical size and use of magnesium.
• The motor is able to utilize a standard size chainring now vs. the reduction gear 1/2 sized chainrings of yesteryear. This raises the chain over the chainstay (which has a nice plastic slap guard), helping to reduce kickback. BULLS chose a sturdy narrow-wide chainring to help reduce chain drops, and also included a plastic wrap-around chain guide. I also appreciate the upgraded crank arms and included plastic platform pedals… though I’d probably swap for larger grippier magnesium wellgo pedals like these.
• Excellent cassette and derailleur setup. With 12 sprockets, each step up or down is shorter and less of a cadence change. This makes riding more comfortable and probably reduces shifting wear (especially with a large middrive motor). The gear spread is 10 to 51 tooth, which is huge! That 501-degree ratio gives you lots of options for starting, climbing steep hills, or keeping up with steep fast descents. The Shimano Deore XT derailleur is one that I trust to be reliable, and it comes with a one-way clutch that stiffens the derailleur and reduces chain bounce when activated. You can click it to the “off” position when removing the rear wheel or performing drivetrain maintenance.
• Great trigger shifters here. The SLX shifters offer multi-step low shifting and a one-step shifter that can be pulled or pushed. I love this setup because I often prefer to push both trigger shifters with my thumb, while keeping my pointer and middle finger on the right brake lever.
• The included locking Ergon grips look nice and feel very comfortable and solid to me. I appreciate how clean the cockpit of this bike is, with cables being routed through extended spacers and then down into the custom frame. Shops can access the cables on this bike fairly easily with the PowerTube 625 removed (as shown in the video review above).
• Magura MT5 hydraulic disc brakes perform well here. They are rated as entry level gravity, which means they can handle fast descents that you might encounter in downhill riding. The extra large 203mm rotors provide a great mechanical advantage over the large wheels and tires, and both calipers use quad piston vs. standard dual piston. This provides more surface area for better grab and rigidity. Both brake levers offer adjustable reach, and the piston design is meant to deliver low friction and great modulation through a force curve curve (the piston isn’t horizontal to the handlebar but perpendicular, the same direction you pull the lever). The reservoir body is made from lightweight “carbotecture” while the levers are aluminum alloy for durability.
• Nice rear suspension design! This is a version of the four bar Horst Link setup which isolates pedaling and braking motion… so you don’t get as much bob when pedaling or squat when stopping hard. The travel path of the rear wheel is more vertical than arced (like a simpler swing arm with fewer pivot points). This preserves chain length and reduces kickback and drivetrain wear. It’s one of the big differentiators for me between the BULLS Adventure EVO AM 27.5 and something like the Riese & Müller Delite Mountain dual battery emtb.
• This ebike was designed for all mountain “enduro” riding with longer travel 150mm suspension and a slack head tube angle. This allows it to take bigger hits with big mountain descents. I prefer a setup like this to a full “downhill” electric bike, because it’s still fun to ride on cross country terrain and around town. The suspension felt buttery smooth to me, and I appreciate the quick release setup on both wheels (thru-axles) because the bike is longer than most cross country bikes due to the slack head tube angle, so removing the wheels could save some space during transport. The bike did fit into my Küat Sherpa lightweight aluminum car rack. Note that I have a self-installed 1.25″ hitch receiver on my Toyota Prius and always take the battery packs off the bike to reduce weight on the rack and hitch!
• I appreciate the Monkey Link magnetic front and rear light receivers, but wish that the optional lights cost less than $170. Still, having lights that are powered by the main battery packs and are so easy to remove is awesome! The headlight has a screw in the bottom that allows it to be aimed down… which is very handy given the slack head tube angle and resulting stem angle.
• BULLS also included a magnetic water bottle mount on the downtube, which is compatible with the Monkey Link Monkey Bottle for $50. It’s also a bit expensive, but works pretty well… You can always remove the Monkey Link adapter plate and install a generic bottle cage in the same spot if you’d like.
• Speaking of water bottles… BULLS designed this interesting top tube rack that has two bottle mount bars hanging off on either side. Pretty interesting! I installed a cage to test it out and found that taller bottles will stick up into the handlebar path during sharp turns and limit how far you can steer in either direction. Consider a short accessory holster like this or very short water bottles like this to use this part of the bike safely. Or, you could mount a folding lock or mini pump here, as long as they aren’t too tall ;)
• BULLS has integrated the magnet for measuring rear wheel speed into the disc brake rotor, so your wheel can stay more balanced, spokes won’t get loose, and the magnet itself won’t get spun out of place or bumped as easily… the reader sensor is also more protected.
• The battery pack locks into the frame using an ABUS core with PLUS keys that can be matched to ABUS locks, it’s a great setup and one of the highest-end locksets around, more info on the official ABUS website here.
• BULLS has a vast network of dealers in the US and Canada, they entered into the North America market from Germany (and Europe) around 2016 and have a strong management and field team, I feel confident that their brand will persist and grown here while some other companies have been less stable, having access to dealers for fitting, tuneups, and post-purchase support is part of what makes this a more expensive bike but also gives you a great end-user experience.
• I like that the BULLS electric bikes have walk mode enabled, it can really be useful for climbing a steep section of trail if you get off your bike (especially if you’re wearing clip-in shoes) or if you get a flat tire, just press the walk mode button on the top edge of the control pad (near the left grip) and then hold the up arrow to make it go.

Cons:

• Due to its custom frame, with dual battery support and internally routed cables, as well as the premium components, and extensive dealer network, the BULLS Adventure EVO AM 27.5 costs a lot. It’s one of the most expensive electric bikes I’ve covered, but it does deliver something special for the money.
• In order to support the dual battery setup, full suspension, and larger plus size tires, the frame had to be reinforced for strength. I noticed the wider Boost wheel hub spacing and bottom bracket spacing (to align the chain properly). The additional metal, rubber, and battery weight on this bike makes it heavier than most competing single battery full suspension products. The bike with both batteries weighs ~65lbs, even with the lightweight air suspension. You can reduce weight by roughly six pounds by removing the PowerPack 500 battery, and the bike will still run and get decent range using the PowerTube 625. The opposite is also true, you can remove the PowerTube 625 and the bike will run, but the remaining battery weight will be positioned high up, which impacts handling more.
• The bike is truly setup for off-road use and does not include front or rear rack options. For someone who is interested in bikepacking or trekking, you may have to use cheaper bar mount and seat tube mount solutions that impact steering and can get bumped out of place easier. By comparison, the dual battery Riese & Müller Superdelite does have some rack upgrade options but isn’t as optimized for all mountain or even cross country riding (specifically the rear suspension design).
• This is a minor note, but the drivetrain does not cycle backwards. Instead, the cranks will freewheel backwards with a bit of resistance (so they don’t spin out of control if you slip off). The result is a drivetrain that is best serviced when the bike is in a stand. I like the ability to pedal backwards and have enjoyed it on some other current generation Bosch motors like the Performance Line for hub gearing seen on the Gazelle Ultimate C380. Perhaps Bosch will add this feature to all motors in the future?
• I love that BULLS positioned the charging port and main battery lock cylinder on the right side of the frame (the drivetrain side), because it’s easy to reach without bending over. However, the second battery lock cylinder is located on the left side of the frame. That means you have to walk around the bike while balancing it or carefully lay it down on the drivetrain side (which risks bumping the long cage derailleur) to unlock the second battery PowerPack 500. Ideally, they would all be on the right side of the bike, but this may be a limitation due to Bosch battery interfaces.
• Be extra careful taking the top battery (the PowerPack 500) off the frame, because once unlocked it just releases and could tumble off. By comparison, the PowerTube battery clicks down into a released position which then requires a finger press to fully release. I dislike that the key is required to re-mount the PowerTube 625 because that takes two hands and the bike doesn’t ship with a kickstand… it’s a lot to manage. However, mounting the PowerPack 500 is also tricky, because it can be tight and require a lot of effort to push into place and hear the “click” sound. Just be careful with it and don’t fully release it or ride until you’re sure it’s mounted. Better yet, keep both packs mounted at all times if possible… unless you have to park the bike outside or in extreme cold or heat (which is hard on the batteries).
• Be careful when lifting and transporting the PowerTube 625 battery because it does not have an integrated handle like the PowerPack 500. The 625 is pretty heavy at 7.9lbs and could easily get damaged if dropped, or really hurt your foot or nice flooring!
• As much as I love the Bosch Kiox display panel, the control pad for it has buttons that require a bit of extra force when pressing and the screen readout is kind of small… that’s why Bosch used colors for the four levels of assist. This way, you can interpret data without having to focus in too much and get distracted trying to read. Consider the Bosch Nyon display as an upgrade if you want a larger display and some cool mapping views.

Useful Resources:

• Local BULLS bike shops directory and map tool to find a local dealer for fitting and test rides.
• Official BULLS North America electric bikes website
• Official MonkeyLink accessories website
• Bosch Ebike Systems motor comparisons on the EBR forums.
• Bosch drive unit comparison on the official Bosch website.