on the fence vs undoubted

on the fence

prep
  • undecided; wavering in one's opinion 

  • Used other than figuratively or idiomatically: see on, the, fence. 

undoubted

adj
  • Without doubt; without question; certain. 

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