Team Ineos rider Froome, 34, was taken to hospital with a reported broken femur after crashing before stage four of the Criterium du Dauphine on Wednesday.
"He crashed in the downhill section of the course at high speed. He hit a wall," team principal Dave Brailsford told France Televisions. "It'll take quite a long time before he races again."
The incident took place during a practice ride on Wednesday's 26.1km time-trial course in Roanne, France.