Gardai have been made aware of a video showing a man leaning out of a car window before knocking an innocent cyclist off his bike.
After the attack in the seven-second video, which has been viewed more than 700,000 times, the cyclist can be seen tumbling into a ditch while the car occupants laugh.
The video was uploaded on Saturday by a Facebook user with the caption 'This is the new challenge boys'. The video uploader has since denied that it was him who pushed the cyclist over.
The clip has been shared online more than 8,000 times, with people broadly criticising those involved. It has since been removed from Facebook.
It is not known whether the cyclist was injured or what part of Ireland it occurred in.
Cycling Ireland, the governing body of cycling in Ireland, notes that there is an increase in assaults against cyclists from passing motorists, according to its CEO Geoff Liffey.
"There has also been attempts to disrupt cycling events and regular cycling paths by introducing serious hazards on these routes," he said.
"Many of these attacks are of a very serious nature and we would advise any persons who experience or witnesses these attacks to report them to the relevant authorities in the area.
"This incident was a disturbing, cowardly and deliberate attack on a vulnerable cyclist. This kind of behaviour is nothing new, but it's becoming more prevalent."
Gardai are advising anyone who has been a victim of crime to contact their local garda station.
A recent study shows the number of cyclists on our roads is increasing, as are the number of incidents.
The number of cyclists injured on Irish roads reached a 10-year high in 2012, when 630 cyclists were injured. Some 53pc (335) of these injuries occurred in Dublin alone.