Sr4 chain ring single ring 4 arm renthals chainwheels are precision cnc machined to extremely tight tolerances to give the ultimate combination of strength and light weight the 7075 t6 aluminium alloy 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 significant