The incident happened some three kilometres from the finish but the Briton escaped with a swollen leg.
"He's sitting with me, he's fine," Team Sky sports director Sean Yates said by telephone.
Cavendish related the incident on his Twitter feed: "Thanks to the d**khead who crashed me at 3km to go today by waving his flag so it wrapped round my handlebars. Bike's broke. Leg's swollen."
Cavendish is among the favourites for the London Olympic road race on July 28.
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What can we expect from the Boks this year when we get down to the business end of the Test season. The truth is that we still don’t know, writes blogger Scrumchums.
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