The archives are full of excellent suggestions from years gone by. My all time favorite method, especially if you have a large quantity of dirty, greasy parts, is to fill up the dishwasher and run a regular cycle. Plain dishwashing soap works fine. I use the top rack. Be sure to dry everything off really well afterward. Anything with a pin or a pivot needs a drop of oil to ward away rust. For non-moving parts (seat posts, cranks and 'rings, bottle cages, etc.) this is a dream. I've never tried it with a freewheel, but those new-fangled off-topic gear cluster thingies clean up real nice.
Be sure to wait until anyone you share the dishwasher with is well away, as this method can lead to domestic tragedy.
Portola Valley, California USA