To set a default Node version for new shells, use nvm alias default <VERSION>:

nvm alias default 1.2.3

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

I like to use the most recent LTS version Show archive.org snapshot as my default:

nvm alias default lts/erbium

nvm: Setting a default Node.js version