The Shimano Ultegra FC-R8100 left crank arm is designed for road cycling and is part of Shimano’s 12-speed Ultegra groupset. Made from aluminum, it offers a balance of stiffness and weight, contributing to efficient power transfer. Available in crankarm lengths from 160 mm to 175 mm, it accommodates a range of rider sizes including smaller riders and triathletes. This crank arm is compatible with a variety of bottom bracket shells including BSA (English), Italian (ITA), BB30, and BB92, making it versatile for many road bike frames. It fits double chainring setups with either 52-36 or 50-34 tooth configurations. The crank arm utilizes Shimano’s Hollowtech II standard and is compatible with any other crankset in that category.