The man, who was from Staffordshire, collapsed while riding on the A5 near Chirk, Wrexham, at about 10:45 BST on Sunday.
He had been raising money for the Douglas Macmillan Hospice.
North Wales Police said officers attended, along with a road and air ambulance, and tried to help members of the public to save the cyclist.
"I am very sad to say that their efforts were not successful," temporary Supt Nick Evans said.
Douglas Macmillan Hospice - known as Dougie Mac - is a specialist palliative care provider in north Staffordshire for adults, the majority of whom are affected by cancer.
A number of charity bike rides for the hospice were being held on Sunday taking in routes from Stoke-on-Trent to Llangollen and back.
A 44-year-old man has died in north Wales while taking part in a charity cycle ride