Jess said she was “unbelievably proud” of her son. The pair aim to ride an average of 50 miles a day.
She said: “Rupert is amazing, he’s going to do really well, he’s super tough and seems to have an innate ability to keep going.
“I’m slightly concerned about keeping up with him but also really looking forward to it.”
Rupert said he was most looking forward to the the Pyrenees, where he and his mum will take on 25 miles of uphill cycling on gradients of about 10%.
“Cycling has helped with my mental fitness,” he said.
“It’s helped with not always being at the house, seeing lots of scenery, being really healthy and eating better food.”