Froome crashed during a recon of the time trial course of the 2019 Critérium du Dauphiné, with his team saying he was immediately taken to hospital.
While his specific injuries are still unconfirmed, Brailsford said the four-time Tour de France winner has suffered a femur fracture following the incident. A picture of Froome being transferred by emergency services shows his right leg strapped up on a stretcher.
Brailsford described the incident as "very serious" and that it will take a long time for Froome to race again. The 34-year-old hit a wall on a downhill section of the 26.1km time trial course in Roanne.
Brailsford told the press: “He’s had a bad crash actually, it sounds like he was at the foot of the descent. It’s obviously very gusty today, and he took his hands off the bars to blow his nose and the wind's taken his front wheel and he’s hit a wall at 60kph or something like that.
"He’s got a bad fracture, he’s badly injured and it sounds like he has a fracture of the femur, to be confirmed, he’s not in hospital yet. He’s just going to get airlifted shortly to hospital, Saint-Etienne, maybe Lyon.
"So obviously we’re trying to manage that at the minute and make sure he’s got the best care. In the meantime, obviously thinking about Michelle, his family and everybody else, make sure that we can give him the best possible care.
“I think in those types of situations what happens in the next hour and a half is crucial so we’ll be on that. In the meantime, we’ve got to keep on racing and I think that’s part of this sport.
"These things happen quickly and you've got to adjust quickly - it's difficult for the guys when something like that happens but you've got to repurpose very, very quickly in this game. It's part of the territory so that's what we'll do for the rest of the race and obviously tonight will sit and assess the situation and go from there.
“There's no doubt about it there'll be an emotional reaction [from the team] to it," Brailsford added.
"I think I’ve got some responsibility there to manage the reaction to the whole team. Looking forward I think it’s too early to assess, he’s not going to ride the Tour, I think that’s pretty clear.”
Froome's wife Michelle tweeted a message from his official account on Wednesday afternoon, saying that her husband had been taken to hospital.
Froome's absence from the Ineos squad will mean they will need to fully back defending champion Geraint Thomas to take a second consecutive title. Thomas is racing at the Tour de Suisse next week as final preparation for the Tour with Froome having opted for the Dauphiné.
It will be a big blow to Ineos and Froome after fairly fruitless season for Brit, who based his entire year around preparing for the Tour. Froome took the option to focus on the Giro d'Italia, which he won, ahead of the Tour last year and was clearly not at his best heading into the French race in July.
Before that, he had won the Tour and the Vuelta a España back to back in 2017 and held the titles of all three Grand Tours simultaneously.
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