What is it
It’s an e-bike with 150mm of front and rear travel from Germany’s Bulls Bikes. It uses a smooth and quiet Brose motor similar (but not the same) to the one used on the Specialized Turbo Levo. What stands out with this model is it comes with a 650Wh battery (compared to the usual 400-500Wh) giving it greater range. Also the battery is internally housed, creating clean design lines and room for a full-sized water bottle. Plus tires are employed to give the bike added traction and comfort.
- Best in class range with 650Wh battery
- Motor is very smooth and quiet
- Hidden battery and water bottle mount
- Stealthy display and controller
- Capable suspension
- Good plus tire setup
- Secure Ergon grips
- Powerful brakes
- Bike looks stealthy with clean lines
- Great value at $ 4699
- Power delivery is inconsistent in high load situations
- No dropper post
- Display is small
- Bars not wide enough for this type of FS bike
- 2×11 is not necessary with this assist and the 20mph restriction
- Rocket Ron front tire bad match for bike’s abilities
Is it legal?
Yes. The Bulls Bike E-Stream is a Class 1 category e-bike with 250 watts of pedal assist power. This puts it in the lowest class of power output. The 250-watt average power output is roughly equal to 1/3 of a horsepower. It’s pedal assist only and delivers output only when sensing input from the rider. There’s no throttle allowed on this class of bike, so the rider needs to pedal for the motor to provide assistance.
Why ride an e-bike?
We’ve been riding e-bikes off and on for the last five years and it is both the biggest growth area of the industry and the biggest source of controversy. It threatens the bike’s distinction as a human-powered vehicle and raises concern about trail access. But it’s also a way to bring new riders into the sport and opens up new options for existing mountain bikers.
In our experience, it made commuting around town more feasible, safer, and faster. Whenever we had an errand to run, the Bulls E-Stream was the easy pick since it was easier to keep up with the flow of traffic, carry heavy loads, and park.
For trail riding, we had to be selective, as e-bikes are only allowed on some of our area trails. The bonus was that in some cases we could ride to trailheads instead of loading the bike on the car’s bike rack. Four-hour expeditions were the norm, as we got to explore our area again and enjoy even the least rewarding fire roads, which is about 80% of our local riding.
The real possibilities opened up while testing in Downieville, California. This area has a massive amount of trail in very mountainous terrain, meaning shuttles are the norm unless you’re among the super fit. But we did several weekdays of riding there with this e-bike when the shuttles weren’t running.
The integrated power unit battery is fully hidden inside the downtube, allowing for a clean front triangle and water bottle space. The 650wh unit lasts approximately 4.3 hours in the medium assist mode. Range is claimed to be 137 miles, but in our experience 40-60 miles was more accurate. More significantly, we were able to climb 5000-7000 feet in one charge, depending on how hard we wanted to pedal.
Based on a proven car power-steering motor, Brose has delivered a silent and vibration-free mid-drive motor produced in Germany. The motor is mounted on the downtube, allowing for a stealthy look and shorter chainstay length. It’s torque-sensing with 4 levels of assist so the rider can choose how much the motor helps with up to 90Nm of torque. It is a high-torque motor, but due to smooth delivery it doesn’t feel more powerful than 75Nm units we’ve tested from Shimano or Bosch.
Old display controllers were huge and clunky, inappropriate for trail riding so Brose went small with a unit not much bigger than a USB stick. With about five buttons and pages of information to display, we found this unit to be too small. It’s a good option to have for some who want the minimalist look, but a little more real-estate would be better. But we much prefer this display/controller to the no display system on the Specialized Turbo Levo bikes where one has to look and reach down to the downtube to view or change modes.
Suspension and Geometry
Head angle is 68 degrees and seat angle is perfect at 74 degrees. Chainstays are fairly long at 468mm and reach for a medium is 440mm. With 150mm of front and rear travel, this is quite the performer with enough controlled suspension for this 50-pound bike. Unfortunately there’s no dropper post, which is a shame for a bike that’s this capable going downhill.
Indeed, it’s no Evil Wreckoning with superior suspension kinematics and damping support, but the E-Stream is enjoyable on big, technical descents like Butcher Ranch in Downieville.
Room for a Bottle
We’re calling attention to this because it’s a big deal these days, but rarely found on e-bikes. To make this possible, the battery is mounted inside the downtube and the suspension bits are out of the way so it can fit a large water bottle. With assisted power, one bottle is enough for most two-hour adventures. Carry another bottle or a pack, and you could conceivably ride for 4-5 hours.
Too Many Gears
Admittedly 2×11 drivetrains offer more gears and smoother cadence changes, but all that seems wasted on this bike. You really don’t need 22 gears when you have the assistance of a motor. And with a speed governor of 20mph, the taller gears on this bike are basically not useable. Unless there’s a long fire road downhill, it’s difficult to use the heavy gears of this bike since the motor will shut off at 20mph making it hard to pedal past about 25mph.
- Travel: 150mm front and rear
- Motor: Brose 250 watts
- Wheel Size: 27.5+
- Tires: Schwalbe Rocket Ron EVO Liteskin TL-Ready 27.5×2.80
- Drivetrain: Shimano 2×11
- Weight: 50.5 pounds
- Powerpack: 37V/17.5Ah/650Wh
- Charging Time: ~3.4hrs to 80%, ~4.5hrs to 100%
- Claimed Battery Range: 137 miles (single charge/optimal conditions)
We are on to the next chapter of e-bikes, where they are evolving from modified commuter bikes thanks to the addition of purpose-built drivetrains and suspension. And they’re starting to get more fun, even on rowdy descents. And while they’re not more fun going downhill than a regular non-motorized trail bike, they’re great for exploration and adventure. Do-once trails can be enjoyed every day, making this a great adventure bike.
Rating: 4.5 out of 5
Price: $ 4699
More Info: www.bullsebikes.com
Q& A with Product Manager Adam Anderson
Mtbr: It seems to cut out at 16mph, then be very interrupted to 19 mph. Is this a kind of ‘Euro’ limit?
Adam Anderson: The Brose motor relies heavily on a rider’s cadence. Ideally, you want to be in 60-90 revolutions per minute range. Shifting to a lower gear may alleviate the feeling of the cut out. It does start to slowly cut off at around the 19.5-20mph zone instead of a hard stop at 20mph.
Mtbr: I was mostly on full boost for one day and it seemed to cut back on boost a bit at 11-13 mph. It happened more at the beginning of the ride. Thoughts?
AA: Again, when riders have experience this, it’s worked to shift to a gear in which you can sustain 60-90rpm.
Mtbr: The tires seem really thin specially for a bike of this weight and ability.
AA: They’re a pretty lightweight tire, but have performed well for us.
Mtbr: It is 2×11. But I can’t even use the big ring since it’s very hard to pedal past 19mph. Is there a reason for this drivetrain?
AA: More gearing allows for more range in any type of terrain. If the bike is in the right gear at 19mph you should be able to even pedal past 20 mph once the assist cuts off, with minimal motor drag. Some people hit higher speeds when bombing downhill, obviously, which the high gears are great for. Most riders we’ve observed spend more time in the big ring than the small.
Mtbr: The 137-mile claimed range is obviously in ideal conditions. Do you have some description of what these ideal conditions are?
AA: Optimal riding conditions is smooth pavement terrain, max tire pressure, no headwinds, and a fairly light rider. We had a customer report a few weeks ago that he was able to do a 25-mile ride, including a 5-mile section with a 3500-foot climb and only used 25% of his battery.
Mtbr: Anything else you’d like to point out about this bike?
AA: Some other key things to note on this bike are that it has the biggest battery with a mid-drive motor on the market at 650Wh. And the Brose mid-drive has a nominal power rating (how much it can sustain over long periods of time) of 250W and a torque rating of 90Nm, one of the highest in the industry. Wheels are tubeless ready (you need a kit with tape, sealant, etc.) but as it came to you are tubed. Elevation capabilities depend on rider and rider’s cadence. This motor responds well to seasoned riders who maintain a consistent cadence of 60-90rpm. There is no elevation where the motor doesn’t work. The 5 modes of assist (including “off”) are set at the following percentage of assist. The actual power is based on rider’s power + what the motor gives.
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