Clarks Anti-Rust CL20RB - 5-7 Speed Chain (boxed)Clarks Chains. Clarks range of chains is extensive, catering for the requirements of all types of riders. From high performance, narrow 8 11 speed self lubricating chains through to half link single speed chains, all have proven superior resistance to stretch. This results in less wear to all drive train contact surfaces so maintaining accurate shifting for longer. Anti Rust. Anti Rust chains combine special surface coating (DACROMET), which enables