autobus vs gruppetto

autobus

noun
  • A large group of cyclists who have fallen behind the peloton (“main group of riders”) in a race. 

gruppetto

noun
  • Synonym of autobus (“a large group of cyclists who have fallen behind the peloton (“main group of riders”) in a race”) 

  • A trill or turn. 

How often have the words autobus and gruppetto occurred in a corpus of books? (source: Google Ngram Viewer )