Optimum power transfer lighter weight maintains efficiency new chain guide design to reduce chain drop 4 arm construction crankset maintains high rigidity and reduces weight hollowglide chainrings maintain smooth shifting whilst reducing weight and increasing stiffness 110mm pitch circle diameter for both compact and regular versions making gear ratio changes easy 50 34t53 39t54 42t55 42t52 36t52 38t new combination weight 683g 53 39t with bottom bracket