On a more serious note, a do-it-yourself car wash would work great. High pressure sprayer and stuff.

Personally I wouldn't recommend cleaning it in the tub... Grease is such a PITA to clean off stuff. If you do, get a tub of hand cleaner from an auto parts store. Gojo is a good brand (get stuff without the pumice). It does a wonderful job degreasing your hands and sink/tub/etc when you're done. Simple green is good for cleaning the bike itself.