The shimano xt m770 hollowtech ii chainset forged hollowtech ii aluminium cranks offer unrivalled strength to weight ratio shimano xt m770 hollowtech ii chainset features lightweight construction with external super smooth bottom bracket bearings for efficient use drilled steel and carbon composite construction middle ring combined with a thicker aluminium double anodized 44 tooth and plated aluminium 22 tooth ring for excellent rigidity and durability sg x chainringsdelivering a s