I use an old school park cyclone chain cleaner (I call it old school because its 20 years old lol.) on the chain which gets some degreaser on the cogs. I then hit the cogs with some foaming degreaser for max coverage and let it soak. I then fold a paper shop towel (a bit tougher than a standard paper towel) to make it thin and go between the gears. When it starts to shred a bit I refold or switch to a new section of towel. Not as clean as the above bike but it usually is pretty good. I always do the chain and derailleur cogs at the same time. I love a quiet drive train when pedaling. Mine needs a good cleaning as we speak !!