SHIMANO 5800 Road Bike Crankset - 34/50 Hollowtech II design has an optimum balance of lightweight and stiffness for better power transfer and acceleration New gear dimensions enhance overall performance Improved gearing for less chain touch in small/small combination Reinforced construction around the chainring area further improves stiffness-to-weight ratio Hyperdrive SG-X chainrings for super smooth front shifting and special tooth profiles, pick-up spikes and ramps help make the front derailleur shifts quiet, easy and trouble-free