Dozens of cyclists from across the GTA gathered in Markham Sunday morning for the 16th annual Ride for Karen.

Considered one of the largest cycling events of its kind in the province, the participants cycled in 100km, 160 km and 200km courses to raise money to support children living with cancer.

The ride was founded in 2002 to celebrate the life of Karen Tobias, who lost her five-year battle with breast cancer that year.

Kirk Tobias co-founded the ride with his brother, Kris, and tells CBC Toronto it was Kris who suggested creating the event to remember their mother.

"After Karen died, Kris said he wanted to clear his mind and he wanted to do it with a long ride," Tobias said. "I said if we're going to do it, let's put up a website. Let's put up some posters, and it all started really small."

Kirk Tobias

Kirk Tobias co-founded Ride for Karen with his brother, Kris (CBC News)

Since its start in 2002 with about 20 riders, the event has grown to raise approximately $2.5 million for cancer support centres and to send kids with cancer to camp.

Each year the ride brings together a unique group of riders.

"We have a combination of riders that are very good athletes who like to ride their bike and love this event because they feel like they're giving back," Tobias said.

"And we have a combination of people who have been touched directly or possibly their family has been touched by cancer, and they use this to create something good out of something very, very difficult."

Ride for Karen

Ride for Karen is considered one of the largest cycling events of its kind in the province. It raises money to support children living with cancer. (CBC News)

John Jenah has participated in the event for at least 12 years and says he got into it for the ride, but the cause drew him back.

"The cause is superb one of the best I've seen," he said. "The kids that go to camp having these huge ailments and burdens on their life. It just gives them a bit of normal quality of life."

All of the money raised goes directly to pediatric oncology camps Camp Quality, Camp Oochigeas and Camp Trillium.

Cyclist Ian Muggridge lost his wife to cancer back in 2002, when Karen died, and also had three young kids at the time. He says the camps do amazing work.

Cyclist Ian Muggridge

Cyclist Ian Muggridge lost his wife to cancer back in 2002. (CBC News)

"Going through the cancer horrors — it's hard," Muggridge said. "Doing anything you can to help kids with cancer and families with cancer. It's pretty amazing."

The camps give children who are battling the disease the ability to be with other children, give their families a bit of a break and help them on their battle to healing, Tobias said.  

"It feels gratifying to be one of the people who puts on the event. In a way it feels a bit sad that we have to put this on," he said. "For me personally, it's a great tribute as a way to honour my mother, Karen."