Tens of thousands of cyclists will flood the streets of Montreal this weekend in the annual Tour la Nuit and Tour de l'Ile.

The two-wheeled touring begins on Friday at 8:15 p.m. at LaFontaine Park, where riders will head to the Lachine Canal, go as far west as Church St. then return along Berri St. to Jeanne Mance Park.

On Sunday the larger ride will envelop the Eastern half of the island of Montreal, with bicyclists heading east from Lafontaine Park to Montreal East, then cutting north to Gouin Blvd, and taking that road West to Christophe Columb and returning to the Park.

Many streets will be off-limits to other vehicles during the day, and people wanting to get in and out of the affected neighbourhoods can expect delays and detours.

Click here for a list of closed streets for Friday and Sunday -- and when they will re-open.