Lightweight hollowtech ii 105 11 speed chainset innovative hollowtech forged and anodised aluminium crank arms utilise a hollow design that minimises flex and keeps the weight low the chainring teeth have been developed to work in conjunction with hg x 11 speed chains for increased contact to provide greater efficiency and improved power transfer hollowtech ii allows the bottom bracket bearings to be spaced wider apart enabling the use of larger bearings and an increased axle diameter