We use a variety of degreasing methods on drive-trains but usually we clean individual items such as a cassette in an environmentally friendly parts washer to remove the majority of caked on gunge and then finish off with the ultrasonic cleaner where needed.
Our eco-friendly parts washer uses a detergent to clean the bike components. Microbes then eat the oil and grease creating a harmless by product of carbon-dioxide and water!
The ultrasonic cleaner uses heated water and a detergent and ultra high frequency sound waves blast away contaminants on chain parts and meticulously clean hidden, interior parts like pins, inner links and inside roller surfaces where the majority of friction occurs. Many dirt shedding lubes work best on a clean chain. A clean chain will last longer and reduce wear on the rest of the drive-train.