Dax Shepard ''needs surgery'' after an accident on a racetrack in California.

The daredevil actor suffered four broken ribs and his clavicle's (collarbone) broken in three places after he went over the handlebars in a motorcycle accident.

Speaking on his 'Armchair Expert' podcast, he recalled: ''I was passing six guys on Sonoma Raceway on a motorcycle and I was braking very, very hard -- hard enough that the back wheel was off the ground for a good 100 yards.

''I was totally at blame. I thought I would be able to slide in between, but someone turned in and I was already under full brake and I couldn't go anywhere.

''I clipped their bumper and I went over the handlebars and I landed pretty hard.''

He continued: ''I've been at the hospital for seven hours today.

''The final tally was four broken ribs, the clavicle's broken in three places, and I need surgery.''

Following the podcast episode airing, the 45-year-old star took to Instagram to thank all the listeners for their concern and get well messages.

Alongside a topless selfie, in which his bruises were on display, he wrote: ''Thank you Armcherries for all the well wishes and concern. I'm in one piece and spirits are high. Sorry for causing concern. (sic)''

In May, Dax's wife Kristen Bell, 40, revealed her spouse was injured when a vehicle he was travelling in fell over and crushed his hand.

She said: ''He went on an essential off-roading trip right when the quarantine began and it was by himself but he was off-roading in the mountains and he had a buddy with him but they were in separate off-road vehicles and he got to an edge of a cliff. He's very embarrassed by this injury because the cardinal rule is you don't put your hands outside the car at any time - that's the only chance of injury. He was sitting on the edge of a cliff and he put his hand up just to look out and the weight of his arm tipped the [vehicle] over. It did crush all the bones in his hands. Shattered.''

The 'Frozen' star explained that Dax was worried about telling her about the accident because he didn't want to get in ''trouble''.

She added: ''He didn't call me. He drove home ... and the first thing he said when he walked in the door is, 'I just don't want to be in trouble.' Which is crazy because he's never in trouble with me. I mean, I'll let you know if I'm disappointed in your actions but I'm an adult, and he's an adult. I said, 'You're not in trouble, but it's not the smartest move you could have made.'''