The renthal 4x alloy chainwheelis precision cnc machined to extremely tight tolerances to give the ultimate combination of strength and light weight the 7075 t6 aluminium alloy rear chainwheels are 66 lighter than steel yet incredibly durable their advanced tooth profile concentricity and accuracy of fit provide maximum power transfer and long life renthals combination of a very high strength base material and an exceptionally hardwearing surface result in significantly increased chainwhee