A high performance chainset from the classic atb group using the most advanced 10 speed dyna sys chainrings forged hollowtech ii aluminium cranks offer unrivalled strength to weight ratio 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 40 tooth and plated aluminium 22 tooth ring for excellent rigidity and durability close ratio ge