Everyone knows Ultegra is for serious riders. The R8000 components are a pro-proven series with the direct trickle down development with the lead coming from the class leading Dura-Ace. The Ultegra group set is about stress-free operation and all day riding comfort.
The 2 by system makes a solid road drive train with the optimized lightweight crank arms with Hollowtech II technology. They crankset design has managed to minimize the wright without sacrificing all that stiffness. It has a wider gear pitch that allows for greater clearance between chain and leading teeth which means it is compatible with Frames with O.L.D. and 135 and 410mm chain stays.