Skip to Main Contents

Two Drive Units Expanding the PAS World

Introducing the stories behind Yamaha Motor's technologies.

The compact PW Series drive unit

Yamaha has been supplying PAS drive units to European bicycle manufacturers on an OEM basis since the latter half of the 1990s, and we have continued making advances in the units’ product maturity through many years of development work. All this led to a breakthrough in 2013 with the release of the PW Series, new drive units that were developed to better fit the needs of the European market. In 2013, Yamaha began supplying these units to Giant Electric Vehicle Co., Ltd. This eventually led to the birth of Giant-brand electrically power-assisted bicycles using the Yamaha-made drive units, and after that, Yamaha began supplying the units to two more European manufacturers.
These units supplied to Europe actually have some structural differences compared to those for Japan. The Japanese-market units use a “chain resultant force” configuration in which the assist force from the electric motor is transmitted to the chain via a special gear to drive the rear wheel. This makes the bicycle better suited for common uses in Japan, which primarily involve rather low-load pedaling like taking children to and from nursery school and shopping trips.
On the other hand, Europe has a long tradition of bicycle use and the PW Series units are designed to be compatible with the market’s strong preference for traditionally styled bicycles. With these units, the pedaling force of the rider and the assist force from the motor are fused into one force within the drive unit and applied directly to the chain to drive the rear wheel. Since this configuration has the drive unit directly turning the pedal crank, the traditional bicycle design remains unchanged and it allows for the use of conventional external gear-shift mechanisms.

Birth of the “YPJ-R” Road Bike: Offering an Assist for Sport and Recreation

The compact PW Series drive units popular in Europe debuted in Japan in December 2015 with a new model named the “YPJ-R.” (#1) Mounting a PW Series unit, the YPJ-R joined the Japanese domestic PAS lineup as a road bike with a completely new feeling to its ride. Weighing around just 15 kg, it is the lightest Yamaha-built electrically power-assisted bicycle model, and can also be fully enjoyed as a road-sport bicycle with the power assist off.
With the YPJ-R, the electric power assist aids the rider with starts and acceleration before smoothly transitioning to the cruising speed range. This makes it a model that alters the nature of the assist from making bicycle riding easier to one that helps the rider more fully enjoy the ride itself. It has a conventional, externally fitted 22-speed gear-shift mechanism and adopts the Shimano 105 groupset for its main components. The newly developed compact battery unit features a USB adapter that allows the battery to function as a power source for charging electronics like smartphones when the bicycle isn’t being ridden.
The switch unit mounted at the center of the handlebars (#2) has a micro-USB port that makes it usable as an electricity source for smartphones or separately sold devices like lights. All this makes the YPJ-R a hybrid bicycle combining the qualities of a high-performance road bike with the advantages of the power assist and battery, expanding the enjoyment of cycling into new realms. This is just one more way that Yamaha’s electronic control technology in PAS bicycles and drive units is opening up new horizons.

Back to