The Capital-born star will lead a group of cyclists from Glasgow to Edinburgh in a bid to raise £1 million for the charity Social Bite.
But Sir Chris wants countless others of all ages and abilities to get involved in the drive to build supported communities in London and Glasgow.
Sir Chris said: “We have got about 600 so far. We are looking to get 1,000 people.
“We are going from Glasgow to Edinburgh and 90% of the time you get a tailwind going that way, so it should be quite a fun ride.
“You are going to be in a big group of people, it’s not all super-serious cyclists, it will be all kind of people on all kinds of bikes. It will be a really fun day. We can guarantee the weather will be fantastic too, that’s a given…
“It’s going to be a celebration, it’s going to be fun, and we are going to raise £1 million, which is going to have a direct impact on many people’s lives.
“We have unlimited numbers online joining from anywhere in the world. There’s a virtual platform, Zwift, that people can join on. The more the merrier.”
The six-time Olympic champion has a long association with Social Bite, previously taking part in sleep-outs.
“With the Social Bite cafe and building the villages, it’s not just a sticking plaster over a wound,” he said. “It’s thinking about how they can solve the problem.
“It is incredible what they have achieved so far but they are a long way from being done. But they are aiming to end homelessness. People kind of laughed at that at the beginning but you see how far they have come.
“Even just meeting people whose lives have been changed and the work that’s been done, the money that’s been raised, that’s what really inspires you to keep going because you can see it is making a difference.
“People have an image in their head about what homelessness looks like and what type of person is a homeless person. And you meet all kinds of people and realise there’s a whole myriad of reasons why people find themselves on the streets. It challenges your preconceptions.”
Sir Chris hopes his quest has the added benefit of engaging people with cycling and highlighting the need for a better network of cycle paths.
“Mental health is a massive part of why some people end up on the streets,” he said. “Physical and mental wellbeing are clearly massively intertwined.
“It doesn’t have to be serious but mental health can fluctuate on a daily basis and if you can exercise, get some fresh air, meet other people in the process, make exercise part of your daily routine, it can help your mental wellbeing, and we can all benefit from that.
“One of the biggest hurdles of getting people on bikes is the fact they don’t feel safe on the roads and maybe aren’t confident riding in traffic.”