Optimum balance between stiffness, strength, weight and rotational performance. The Hollowglide structure reduces the weight while maintaining the same strength for better power transmission and faster and more precise forward shifting. Chainring combinations 52-36 and 50-34dts. Crank lengths of 160, 165, 170, 172.5 and 175 mm. As part of the new 12-speed road bike series, the FC8100 crankset benefits from the legendary chainring changes and overall efficiency of the Shimano transmission. The Ultegra crankset is now available in lengths from 160 to 175 mm, allowing for increased performance and a better position for smaller riders, triathletes and riders with specific riding position requirements.