Pippa Middleton donned the lycra today to join 22,000 cyclists riding from London to Brighton to raise money for heart disease research.
The Duchess of Cambridge's younger sister and their brother James Middleton were taking part in the 54-mile route as ambassadors for the British Heart Foundation (BHF).
The yearly event is billed as "Europe's largest and oldest charity bike ride" and was launched 40 years ago.
Since 1975 it has raised over £65 million for heart disease research and gone from 36 riders in its first year to the over 20,000 who turned out today.
Miss Middleton, 31, said: "This event is testament to the fact that cycling is such an inclusive sport that everyone can enjoy.
"Through the money raised, the BHF can continue to help the millions of people affected by coronary heart disease - the UK's single biggest killer."