The shimano ultegra fc 6700 10 speed chainset hollowtech ii the hollowtech ii 10 speed ultegra chainset offers an ideal balance of light weight and stiffness making it the perfect choice for both enthusiast and competitive riders hollowglide hollow outer chainring gives vast improvements in rigidity by virtually removing outer chainring flex and hugely improves shift performance even under high load shimano ultegra fc 6700 10 speed chainset hollowtech ii features the cha