Video has emerged of a tree branch falling on top of three cyclists while riding on a northern Sydney road.

The footage shared online by George Gittany at the weekend shows the trio riding at the centre of a large convoy on Mona Vale Road in St Ives when struck by the falling branch.

Did you witness the accident or know the cyclists involved? Email news.feedback@ninemsn.com.au

An unidentified man, who fell to the ground before appearing to trip up a riding partner, lies still in the gutter beside his mangled bike, cradling his head.

While the other floored cyclist and a third victim appear shaken but unharmed as they peel themselves up off the road.