Carrierwave on Heroku

production.rb

  CarrierWave.root = Rails.root.join('tmp')

routes.rb

  match 'uploads/*path', to: 'uploads#show'

uploads_controller.rb

class UploadsController < ApplicationController                                 
  def show                                                                      
    headers['Cache-Control'] = 'public; max-age=600'                            
    send_file Rails.root.join("tmp/uploads/#{params[:path]}"), :disposition => 'inline'                                                                         
  end                                                                           
end                                                                             

Don't forget the requirements on the route. Without it, someone could access other files in your app with a little url hacking.