The Sound of full Power

6 E-Bike-Motors in a Comparison Test

The motor is the component that most significantly defines the riding characteristics of an EMTB. That’s why, in our video series, we focus on comparing the most exciting full power motors of 2025. Part one is exclusively about the sound of the motors.

Youtube Video

The most exciting full power e-bike motors are coming in 2025 from Bosch, DJI, Shimano, Yamaha, and Brose Motors. Some of them, like the DJI Avinox or the Bosch CX of the fifth generation, have recently caused quite a stir. Others, like the Brose (Specialized 2.2) or the Shimano EP801 motor, have almost been overlooked by the media in comparison. Therefore, we organized a test of the most exciting models, in which you can compare the performance of the newcomer motors one-to-one with those of the somewhat older motors.

Currently, as an e-bike buyer, you are faced with exactly this decision. Do I get a bike with a brand-new motor, or are certain compromises with older motors acceptable if the bike’s price is right? In this first video, it’s exclusively about the noise level these motors produce. For this purpose, we tested the motors uniformly in three different scenarios.

E-bike motor test — The sound of an EMTB has two dimensions. On the one hand, some motors rattle on the descent. On the other hand, there is a certain assistance noise from the motors when they provide power uphill. We have checked both scenarios.

These tests had to be completed.
Sound test

Gear rattle (stairs): How much do the gears of the motors rattle on a staircase?
Gears rattling (Trail): How much of the drivetrain noise is actually audible on the trail?
Assist sound while pedaling: What sound do the motors make when assisting at different power levels and cadence frequencies?

This motor was part of our group test.

Bosch CX Gen 5

Bosch CX Gen 5 Sounds Bosch CX Gen 5 noises
The Bosch Performance Line CX received an update in fall 2024. The latest version (known as Generation 5 or BDU38) has big shoes to fill since its predecessor was Germany’s most popular motor. Bosch mainly focused on fine-tuning the motor’s soft skills in this new iteration. While the power and torque remain at the familiar 600 watts and 85 Nm respectively, they have primarily upgraded the motor control and soundscape. Is that enough to hold its own against the latest competitors?

The motor was installed in the M1 AM 600 test bike.

Bosch CX Gen 4

Bosch CX Gen 4 noises Bosch CX Gen 4 Test
The Bosch CX of the 4th generation already has a successor, yet it is still sold on many new complete bikes. It has captured the hearts of EMTB riders mainly through its carefree character. The performance with 600 watts and 85 Nm of torque is still state of the art. In terms of weight and installation space, this motor is still on par with its successor. But can it still convince with its soft skills?

The motor was installed in the Radon Render 9.0.

DJI Avinox

DJI Avinox Noise DJI Avinox weight
The DJI Avinox is undoubtedly the breakout star among the current motors. It combines up to 1000 watts of peak power with 110 NM of torque at a weight of just 2.5 kg. The touch display and high-resolution sensors set a new industry standard. But what about the sound? Can the supposed Chinese super-unit hold its own against the competition? We were surprised by an incident during the test.

The motor was installed in an Amflow test bike.

Shimano EP801

Shimano EP801 noises Shimano EP801 Test
The Shimano EP801 motor has been on the market for over 4 years but is still Shimano’s latest unit. When a manufacturer aims to build a lightweight, affordable full-power bike, this motor is still very commonly used. Offering slightly more power than Bosch’s competition (approximately 600 W) and identical torque (85 Nm), the motor is considerably lighter. Additionally, as a manufacturer, you have unrestricted access to third-party batteries.

The motor was integrated into the Canyon Spectral:ON.

Giant SyncDrive Pro2 (Yamaha)

Giant SyncDrive Pro 2 Giant SyncDrive Pro 2 Review
Yamaha has been in the eMTB circuit for a long time, but as an engine manufacturer, it doesn’t get as much attention as Bosch or Shimano. Giant, as a major bike manufacturer, is increasingly focusing on these models, equipping the Japanese hardware with its own software. Under the SyncDrive label, Yamaha’s motors have achieved considerable distribution and relevance. Is there untapped potential in the SyncDrive motors?

The motor was installed in the Giant Trance X Advanced E+.

Specialized 2.2

Brose motor test Specialized 2.2 Motor Test
Similar to Yamaha, Brose faces a similar situation. The German motors have gained a huge following under the Specialized label. This combination of German hardware and American software has set early standards in the young e-MTB scene. With 90 Nm of torque and just over 600 watts of power, they slightly outperform the motors from Bosch and Shimano in these aspects. However, the big advantage lies in the belt drive. Is this technology really as much quieter as is commonly claimed?

The motor was installed in the Specialized Turbo Levo.

We conducted all tests with uniform tires from Schwalbe. Additionally, for cadence monitoring, we installed X-Power power meter pedals from SRM.

Standardized requirements for every motor

To ensure consistent conditions for each motor, we didn’t just stick to uniform test trails. We also mounted the same Schwalbe tires on every bike. Up front, we used a Magic Mary and at the rear, a Big Betty. To verify cadence (and for further tests, power as well), we employed X-Power SPD pedals from SRM. We extend our thanks to all partners for their support in this test. Additionally, the online retailer Alltricks was a crucial partner in executing this extensive test.

E-bike motor test — Our sound check was just the beginning. More tests are yet to come.

These reviews are still to come.

Alongside this initial test on the sound of these motors, further tests will follow with the same test group but different focuses. Subscribe to our newsletter in the footer of the website to not miss the videos on the topics of performance, range, and motor control. This will give you a complete picture for your e-MTB purchasing decision.

About the author

Ludwig Döhl

... has spent more than 100,000 kilometers in the saddle of over 1000 different mountain bikes. The bottom line from many hours on the trail: mountain bikes are awesome if they match your personal preferences! With this insight, he founded bike-test.com to help bikers find their very own dream bike.