Depending on your setup it could not be loading for several reasons.
For instance, when you open a shell (depending on the OS distribution) bash files are read in various orders, although here is what the standard looks like: ( I believe Ubuntu is slightly different so you might want to check if thats your distro).
# for interactive login shells (when you login to a terminal)
/etc/profile
/home/<user>/.bash_profile
/home/<user>/.bash_login # if there is no .bash_profile
/home/<user>/.profile # if there is no .bash_login
# for interactive non-login shells (i.e. opening up a new tab)
/etc/bash.bashrc
/home/<user>/.bashrc
What happens when you directly source your .bashrc? Does it then find rvm? If so, then its just a matter of making sure your .bash_profile sources .bashrc aka:
# in .bash_profile
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi
If this isn't the cause you could dive into the rvm documentation or switch to rbenv which IMHO is a much simpler solution.