The second edition of Montreal's Grand Prix Cycliste race began Saturday with the UCI WorldTour event.
Most streets were closed at 7 a.m. Saturday and are set to reopen at 7 p.m. Sunday.
Organizers are also warning that access to hospitals in the Côte-des-Neiges borough may be difficult.
More than a hundred cyclists taking part in the event will do 17 circuits on a 12.1-kilometre course to complete a total distance of 205.7 kilometres.
Australian Simon Gerrans, 32, won the Quebec City race on Sept. 4. If he wins the Montreal race, he would be the first in the world to win both races.
Montrealer François Parisien ended the Quebec City race in 10th position.
The event is free for spectators.