Three-year-old Reggie, the son of local couple Sean Millwood and partner Amy Hickman, suffers from an extremely rare disorder called Phelan-Mcdermid Syndrome (PMS).

And, so touched by the youngster's plight, Mr Williams decided to don the lycra and ride from Cardiff to the Muswellbrook RSL Golf Club on July 19 to not only raise awareness for PMS but funds for the family to support their ongoing cost of living while dealing with the lad's condition.

"I've known Amy since I was 12 - more than 20 years," he said.

"So, it's a cause close to my heart.

"I'm aiming to surpass the $10,000 mark.

"So far, we've amassed more than $8000 on the GoFundMe page.

"We've got a few other things in the mix, too."

The Ride 4 Reggie Family Fun Day will also kick off at the Muswellbrook RSL Golf Club from 1pm, just an hour or two before Mr Williams cycles into town.

Kids' entertainment, a jumping castle, face painting and balloon animals, a mystery raffle, bake stall, an auction - featuring items such as autographed South Sydney Rabbitohs and Newcastle Knights' NRL jerseys, and a pair of signed boots by New Zealand Test and Canterbury Bankstown Bulldogs star Keiran Foran - and a special Reggie-inspired menu are planned.

"I know the trek to Muswellbrook won't be easy," Mr Williams said.

"It'll definitely be different, riding outside in the elements.

"But, I'm keen to do whatever I can for Amy, Sean and Reggie.

"Thanks to everyone who has gotten involved and donated/sponsored us for the big day, you're all absolute bloody legends."

To support Mr Williams' quest, or make a donation, visit https://www.gofundme.com/6ziw4qw?fbclid=IwAR2IHHIdannopPEXKk197c2MAPBoPgYupjMXcD8mFQKQHXxGRJzFRYslrrI