On ubuntu server 10.04 you might want to avoid rvm and rbenv and just go straight for installing ruby on your server.
Install openssl development libraries and prerequisites.
Install yaml
Install ruby
Install rubygems
This is applicable if you want to run a certain version of ruby globally on your production server. If there is alreadt a version of ruby installed, check /usr/bin/ruby, /usr/bin/gem and /usr/bin/bundle and update the links accordingly.