Skip to Main Contents


The compact, light weight center mount unit



1. Center mount unit (bottom bracket motor)

2. Support up to 25km/h

3. Motor

  • Rated power: 250W
  • Peak torque: 80 Nm
  • Continuous maximum torque: 70 Nm
  • Direct transmission of the motor power to the crankshaft

4. Sensors

  • Torque sensor, speed sensor, crank sensor

5. Weight

  • 3.5kg (excl. Drive Sprocket)

The compact, light weight center mount unit

There are two main advantages in center mount type units. First, the gears originally equipped to the bicycle can be utilized as a part of e-Bike systems, allowing for optimal motor performance. Second is weight distribution. Centralization of mass leads to a natural weight balance while riding and while stopped, retaining the superior weight distribution of a bicycle.

We have succeeded in developing one of the world's smallest and lightest drive units. This involves the direct transmission of the motor power to the crankshaft, providing for a minimal exterior design. The high-power motor has ample amounts of low-down torque, making electrical assist on hills and gravel roads - under the hardest of conditions - extremely powerful.

Support Level

Instantaneous maximum value at pedal crank axis < 2.8 < 1.9 < 1.0 < 0.5

Image of the torque at starting

Motor torque / Input torque

Notes: These figures are standard numerical values of YAMAHA.
These figures may change depending on the differences in a characteristic setup, and the differences in vehicles composition.

The triple sensor system

The "triple sensor" system is what holds the product concept of "smooth and powerful" in place. The three sensors are the: 1. a torque sensor that detects pedaling power, 2. a speed sensor that detects the bicycle's speed, and 3. a crank sensor that detects the number of rotations through pedaling. By equipping the three sensors to the unit, the rider is supported by continuous assistance under every riding condition. The constant assist is what allows the "smooth and powerful" concept to come alive during the ride.
The torque sensor has great response, resulting in an optimal assist timing through fine-tuning the motor control.

Localization for the European Market

The PWseries is a new system that was developed for a perfect European market fit. With a strong focus on the "organic" bicycling feel, the end product is a natural ride for sport-riding bicycle enthusiasts and every-day riders alike.

Back to