I Have!
I have done it. You just need to gauge how hard you are going, and listen to your body. Things to keep in mind: keep you bike in one piece, you don't want to be stressing during the week before the race looking for a part you broke during the race. Make sure you eat well after the race (ie: recovery foods). Listen to your body for the rest of the week to make sure you are good-to-go for the 24 hour event.
Which 24 Hr event are you racing??