* Van Vleuten leading road race when she crashed * Three vertebrae fractures * Tweets that she is 'fine' (recasts, adds van Vleuten comment) By Martyn Herman RIO DE JANEIRO, Aug 7 (Reuters) - Annemiek van Vleuten suffered three fractured vertebrae and a concussion after a horrifying high-speed crash in the Olympic women's road race on Sunday but the Dutch rider said she will be fine and was more disappointed at missing out on a medal. Television pictures showed Van Vleuten slamming into the road and a stone kerb after losing control of her bike when leading on the final descent towards Copacabana beach with around 15km of the race remaining. "I am now in the hospital with some injuries and fractures, but will be fine," Van Vleuten said on Twitter. More...