Expand tinyurls using ruby

Just a tiny thing but handy and I couldn’t find it anywhere else (I’m new to Ruby and I’m coding by google so don’t expect great style here, but this seems to work):

require 'net/http'
require 'uri'

url = URI.parse "http://bit.ly/1Zw502"
if url.path.size > 0
  # catches case where you get an url like
  # http://planetrdf.com with no slash
  # this catches this but doesn't look it up
  req = Net::HTTP::Get.new(url.path)
  begin
  res = Net::HTTP.new(url.host, url.port).start {|http| http.request(req) }
  case res
  when Net::HTTPRedirection
   uu = res['Location']
   puts uu
  end
 end
end

uu is the expanded url. Is there a better way than this? Is it me or is Ruby documentation a bit thin on the ground? (Thanks to Damian for pointing out to me how tinyurls work – I’d never bothered to look before!)