The shimano ultegra 6800 5236 11 speed chainset offers the ideal balance between lightweight stiffness and performance making ultegra the perfect choice for the racers and the weekend warriors the hollowglide hollow outer chainring gives a vast improvements in rigidity by virtually removing outer chainring flex and hugely improving shift performance even under load shimano have used their hollowtech ii technology which gives a wider stiffer base by placing the bearings further apart and la