When ever I get a really dirty and greasy bike I start with Purple Power mixed at 1 part cleaner and 3 parts water in a 1 gal pump sprayer and so far I haven't damaged the finish on any bicycle I have used it on,however I have seen it dull the finish on a few lawnmower decks. I just think most bicycles come with a better finish then some of the cheaper lawnmowers and a good wax brings back the shine on them. For just a general cleaning I use car wash and a sponge.
