Gardaí were yesterday searching for four men in a dark-coloured car who took part in the attack.
Conor McKenna, aged 13, had the skin ripped from his knees, elbows, and forearms after the incident just outside Emyvale, Co Monaghan.
A keen cyclist, Conor had recently joined his local Emyvale Cycling Club and went for a training spin just after lunch on Monday.
He was riding his new carbon-fibre racing bike and was kitted out in his cycling gear and helmet as he set out on a planned, 35km trip.
He was passed by several cars as he approached Corracrin church on the Emyvale to Monaghan road.
However, one of the cars, which contained four men, pulled alongside him and the rear window was lowered.
One of the men sitting immediately behind the front passenger seat suddenly reached out and grabbed Conor as he was picking up speed.
He pulled Conor sharply towards the moving car and then violently pushed him away from the vehicle.
Conor lost control of his bike, careered into the roadside hedgerows, and then crashed onto the ground at speed, smashing his helmet in the impact.
He ended up in the middle of the road, tangled in the bike and with his feet still clipped into the pedals.
Traffic following behind had to take emergency action to avoid hitting him and a van driver raced to help him and to divert traffic.
A neighbour who knew Conor was also passing and immediately tried to set off and track down the car involved in the incident, but was unable to catch up with it.
An ambulance was on the scene within a few minutes and Conor was rushed to an accident and emergency centre in Monaghan town. After an initial assessment, he was transferred to Cavan General Hospital.
Gardaí were quickly on the scene and were yesterday believed to be following a definite line of enquiry in connection with the incident.
Conor’s father Richard said yesterday that his son had been very shocked by the incident, and he was at a loss to know what to say to him when he recovered from his injuries and wanted to return to training.
“What do I say to him after something like this?” said Mr McKenna.
“The law of the land should be put down as forcibly as possible on all those who were in the car. It’s not just the person who did this to Conor who is responsible. That car had to slow down so that they could do this to him. To do something like that to a young lad — they’re fit for anything. Why would you even think of doing something like that?
“Conor got a terrible shock and has no skin on his knees, his elbows or his forearms — he was wearing his cycling gear and because of that he had no protection.
“He hit the road with his head and the helmet was smashed because of the severe impact.
“Thank God for the helmet. It would be a different story if he didn’t have it.”