The incident occured on Faussagh Avenue in Cabra at around 7.40pm on Monday and involved a car and a e-bike.
The cyclist, a 50-year-old man was taken to the Mater Hospital with serious injuries.
The road has since opened up after Gardaí carried out an examination.
Gardaí have sent out an appeal to witnesses of the incident to come forward, they are asking road users with dash cam footage to make it available to the Gardaí.
Anyone with information is asked to contact Cabra garda station on 01 666 7400, the garda confidential line on 1800 666 111, or any garda station.
