>>1996314thirding just drizzle water from the hose to initially wet it down and then rinse. you get the dirt off by soapy cloth and brush, not blasting it with water. you don't want water getting into anything that falling rainwater wouldn't touch.
mild soap. you can put car wax on it if you want, it'll stay nice longer and be easier to clean thereafter. I even waxed the finish on my brake calipers. they look silver but actually it's a champagne powder coat finish on them. lots of components have similar finishes.
I have a whole separate set of rags and a drivetrain-specific brush I use on the chain and gear clusters. don't forget your pulley wheels on rear derailleur, they're often plastic and accumulate the most gunk. press a rag on one side and reverse the crank, then move the rag, repeat until not leaving gunk marks, then press the other side. do the chainrings the same way. when cassette is gunky I drizzle water, flush with solvent, and use my Park thin, stiff brush between the gears, also there's a hook thing on it that scrapes the innermost surface., drizzle water, repeat if needed. also, pic related every once in a while especially if you ride in rain/puddles/mud.
chain cleaning and lubing is important but there's a million opinions about what is the right way so I'll leave you to that on your own.
