Melvin Chain TensionerDescription Paul Components Melvin Chain Tensioner lets you run a single speed setup on a frame with vertical dropouts by adding chain tension where a rear derailleur would normally mount. Melvin bolts to the derailleur hanger and uses two pulleys to manage chain tension and chain wrap, helping keep the drivetrain quiet and consistent. It also includes chainline adjustment via spacers at the mounting pivot, and the pulleys have side to side float to