It's possible but very hard too...programming in node.js is programming at low level..if you haven't good knowledge about javascript, ajax, etc, It will be almost impossible..
neither node.js as express are replaces for sinatra or rails...theses have other niche..while rails and sinatra are utils for create medium or big sites, node.js, express, faye..etc..are utils for create small but fast web apps...create a big site or complicate site using node is similar to cut your veins
