Park Tool Bio ChainBrite
Bio ChainBrite Bicycle Chain and Component Cleaning Fluid is a 100% biodegradable, natural, plant-based degreaser formulated for use in Park's CM-5.2 Cyclone Chain Scrubber or as a general purpose degreaser. It won't harm alloy, plastic, or rubber parts.
Use CB-4 full strength, do not dilute with water. Cover parts in solvent and scrub using a brush.