I read \"Relationships between Rubygems, Bundler, and RVM\" before asking it again.
Well, there are many questions like this, but people who answered say they work
I'm also trying to understand how it works. The blog "Advice on using Ruby, RVM, Passenger, Rails, Bundler, … in development" helped me have a better overview.
BTW, it's a translation of a French article, the French version is better.