The Prince of Wales couldn't contain his giggles as he helped to launch a charity bike ride from his country home, Highgrove.
Prince Charles, 72, who admitted he hasn't cycled for years but had got in a quick practice before his public engagement, joined cyclists to kickstart the British Asian Trust's 'Palaces on Wheels' event.
The future king kept his cool in a beige suit in the UK's heatwave as he cycled alongside partipants on a borrowed a British-made Pashley bike.
WATCH: Prince Charles giggles as he launches charity bike ride from Highgrove
The sponsored bike ride will cover 250 miles over the course of four days, stopping at a number of royal residences along the way. Beginning at Highgrove on Thursday, cyclists will travel through the Cotswolds towards Windsor Castle, onto London to Buckingham Palace, from the Tower of London to Cambridge with riders celebrating the end of the cycle at Sandringham on Sunday.
As Charles heard about their cyclists' previous fundraising rides, he jokingly told the riders after seeing them in tight fitting riding gear that they were "a very good demonstration of why I don't wear Lycra!"
"It's a nightmare getting into it," he added.
Charles helped to kickstart the charity bike ride from Highgrove
The Prince founded the British Asian Trust in 2007, alongside a group of prominent British Asian business leaders. The charity works to reduce poverty and disadvantage for communities in South Asia. This includes work in areas of anti-trafficking, education, livelihoods, mental health and conservation.
The route will take riders past four royal residences
The engagement took place on what would have been the Duke of Edinburgh's 100th birthday.
The Prince of Wales and the Duchess of Cornwall paid tribute to Charles' late father by sharing two touching images of Prince Philip on their social media pages. The first showed the Duke last July in a ceremony to transfer his role of Colonel-in-Chief of the Rifles to Camilla, and the second, a childhood shot of Charles welcoming his father home from a trip to Malta in 1951.
The caption read: "Remembering The Duke of Edinburgh, on what would have been his 100th birthday."
Make sure you never miss a ROYAL story! Sign up to our newsletter to get all of our celebrity, royal and lifestyle news delivered directly to your inbox.