Police say the woman lost control of her bike at a dangerous intersection.
The woman in her 20s was biking along St-Pierre Avenue under the Ville-St. Pierre exchange overpass during the height of rush hour.
Police say as she came underneath the overpass for Highway 20, she lost control.
"What we think so far is: she felt she didn't have enough space between the sidewalk and vehicles, so she tried to get on the sidewalk and this is where she lost control and fell on the street," said Olivier Lapointe, spokesman for the Montreal police.
The woman fell into the path of a flatbed truck. The driver didn't know he had hit her until passing motorists flagged him down.