The Hollow Tech II 11-speed Dura-Ace chainset offers the optimum balance of light weight & rigidity,  making it the global choice for road racing's elite riders. Key 
 Features: Hollow outer chainring,  giving vast improvements in rigidity & increased weight savings The hollow outer chainring has essentially removed outer chainring flex,  hugely improving shift performance making it precise even under high load These industry leading Hollow Tech II 4 arm cold forged hollow crank arms have been evolved to increase rigidity,  reduce weight,  & improve strength The teeth have been developed to work only in conjunction with the 11-speed chains for enhanced contact providing more efficiency & enhanced power transfer There is a wide range of chainring ratios & crank arm lengths available enabling customisation for all riders & racing disciplines Hollow Tech II integrated bottom bracket design uses a wider bearing placement & larger axle diameter for increased stiffness & efficiency Bottom bracket seal design has a minimal bearing interface gives superbly smooth rolling & increased durability Weight: 609 grams (50-34T)