A cyclist who was seriously hurt after crashing in the city's west end just over a month ago has died.

The 40-year-old man succumbed to life-threatening head injuries sustained after a crash at the intersection of Davenport Road and Caledonia Park Road on July 15, police said in a Monday release.

Police said just after the crash that "the severity of the head injury indicates that he was not wearing a helmet."

The man was riding southbound at Caledonia Park Road "at high speed" as he approached a green light on Davenport, according to police.

When the light changed, the man made a sharp left turn eastward onto Davenport's westbound lane, and then lost control and fell onto the roadway.

Police also issued an advisory in the Monday release that said: "While helmets are not mandatory for those over [18], Traffic Services would remind everyone that helmets are your best defence against brain injuries that result from falls. Parents need to be vigilant in ensuring children wear their helmets at all times when riding their bicycles."