Specifically designed for use with E-bike drivetrains, this left Hollowtech crank arm features a hard-wearing hollow aluminium construction. This makes it perfect at handling all the abuse that comes with all-day epics in the mountains. Shimano has also equipped this model with an anodised finish, which gives it additional protection against corrosion and the elements. Another benefit of its hollow-forged construction is it overs a superior strength to weight ratio, so you can benefit from its exceptional durability without adding any unnecessary grams to your E-bike. Technologies: Hollowtech: Hollow forged crank arms. A lightweight crankset not only reduces the bike’s weight, but decreases rotating mass to aid in acceleration. The challenge is to reduce the weight of the crank without reducing its strength and rigidity. SHIMANO’s advanced forging technology has solved the problem through the HOLLOWTECH crank. Just like high-quality frame tubing, a hollow crank arm can provide amazing strength and rigidity at very lightweight.