Pelletier was struck by a car when he tried to pass a large group of other cyclists on a narrow rural road near Arlington, Wash., about 80 kilometres north of Seattle.
Pelletier's family released a short statement on Monday though the B.C. Cancer Foundation, saying they were heartbroken by his death.
"At 16 years of age, Xavier was a talented young athlete who died riding in support of his uncle who is a cancer survivor. A gentle soul, he was passionate about cycling and cared deeply for his family, friends and community," said the statement signed by Nigel Halsted, on behalf of the family
"On behalf of our family, we would like to express our heartfelt appreciation to the many who attended the scene including: first responders, Arlington police and fire services, volunteers, and fellow riders, who compassionately came to Xavier’s aid.
"Their immediate support and tireless efforts give us comfort in the knowledge that nothing more could have been done to save his young life."
At Pacific Christian School, principal David O'Dell said the 16-year-old had proven to be a committed and generous young man during the three years he knew him.
"Xavier was very involved in athletics here at school. He was part of our sailing team, our rugby team and volleyball, and most recently he had participated in our triathlon," said O'Dell.
O'Dell said final exams scheduled at the school on Monday had been made optional and students have been offered counselling if they need it.
The car that struck the boy was driven by a 50-year-old Arlington woman, police said. She was driving below the speed limit and is co-operating with the authorities.
About 2,600 cyclists participated in the 230-kilometre bike ride, which left from Surrey's Cloverdale Fairgrounds on Saturday and arrived in Redmond, Wash., on Sunday.
- Read more about the Ride to Conquer Cancer
This year, participants raised $10.4 million to support research at the B.C. Cancer Agency.