The riders are part of the Variety Cycle for Variety Children's Charity that starts in Sydney and ends more than two weeks later in Hobart.

The ride, now in its second year, is the brainchild of Christopher Mapp. He launched it last year with a ride to Uluru.

"I was sitting around a table with a bunch of mates and I threw out the idea of a ride to Uluru," Mr Mapp said.

"All five said they were in straight away. In the next year of planning all five of them pulled out but we then had 200 participants so we didn't need them.

"It's now in its second year and if we achieve what we think we'll achieve we will have raised $1.2 million over those two years."

Riders can either take part in the whole event or nominate stages to ride in. Mr Mapp said the riders are broken up into groups each day so people are cycling with others at a similar fitness level.

"Basically, as long as you've been on a bike before there's a group for you," he said.

"The first group will be averaging 30-plus kilometres per hour but the fifth group will be pedalling along at 20. They may take longer but every group has support vehicles front and back and they pull you over to feed you and make sure you're watered.

"It's more like a ride with your mates than a race."

It's also a ride with a long section over water - the Bass Strait.

"It's overnight so we hopefully will be sleeping but I know we're going to have stationary bikes as well so we can have a bit of fun," Mr Mapp said.

"We can tell everybody there was some pedalling while we went across Bass Strait as well."