Yamaha Goes Small with Latest e-Bike Drive Unit

Yamaha has launched its latest eBike drive train claiming improved power-to-weight performance in a much more compact format.

Its new PWseries S2 drive unit claims and output of 55.3ft-lbs maximum torque and is more than 7% more powerful than the previous PWseries ST, while weight has been cut to just 2.85kg (6.27lbs), 16% less than the previous design and now claiming to be one of the lightest in its class. At the same time, its overall mass has been reduced by 20%.

Greater freedom in frame design

The smaller dimensions of the new unit offer eBike manufacturers greater freedom to produce new generation frame designs with features such as increased ground clearance for improved performance on technical terrain particularly suited to off-road applications.

The PWseries S2 features a 22.8mm (0.9-inch) shorter bottom bracket than the PWseries ST, enabling improved pedaling efficiency and feel and is coupled with Automatic Support Mode. Its new ISIS bottom bracket axle interface delivers increased rigidity, making this new mid-class drive unit ideally suited to the needs of e-MTB riders and is fully compatible with a front double chainring.

— Paul Myles is a seasoned automotive journalist based in Europe. Follow him on Twitter @Paulmyles_

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