I just apply a LOT of lubricant (Teflon types, typically) and use THAT to clean the chain, cassette and chain wheels. A bunch of black gunk comes off on the rag that I floss the cassette and scrub the chain with, and everything is left looking clean and shiny. Frequency depends on how wet and dirty the rides are, but I'm guessing they go about 2-300 miles between such treatments.