I think a sanitary sewer will handle simple green mixed with bicycle gunk. The majority of the gunk on bicyles is more dirt with a little oil to bind it together. A sanitary sewer is designed to handle these loads. The solids (dirt) will be settled out, and the small amount of oil is probably digested in the process. The Simple Green probably starts breaking down the oil. I'll venture to say a pair of greasy auto mechanic overalls contains more grease/oil than what is on our bikes. Yet, we could wash these overalls and dispose of the oily/greasy drain water into the sanitary sewer system.

Now, I wouldn't dump it into a storm drain that feeds directly into the ocean - that's not good.