A road rage driver caused a pile-up of around 50 cyclists after they held him up on a training run through a Sydney suburb.

The resulting smash forced an articulated lorry to lock up, jack-knife and screech to a halt behind the bikes while cars had to swerve to avoid them.

Witnesses said the driver who caused the accident became angry, accelerated in front of the pack and then slammed on his brakes, giving the riders no time to stop.