The smell of citrate cleaners like Simple Green is not good for you, I was told in a hazardous materials seminar -- check out the MSDS. I don't like these for another reason: they rely on salts, and that can't be good for a steel bike.

I am a soap-and-water followed by auto wax devoté, and I do keep my bike clean. If there's any crud that the soap and water doesn't remove, auto wax with some cleaner in it can usually do it, with a little bit of elbow-grease. The wax has a somewhat petroleum base, which removes greasy stuff, and replaces it with clean waxy stuff.