Olympic gold medal-winning cyclist Jamie Staff waved the starter's flag at a children's cycle race in Kent to raise money for Leukaemia Research.
The Bikeathon Kidz event, at Lydden Race Circuit near Canterbury, was aimed at children aged from two to 14, but parents were also allowed to enter.
Sprint cyclist Staff, from Ashford, gave riders advice on getting round the track before starting Sunday's race.
"It is a really good turnout and they look like they're having fun," he said.
"Cycling is my passion and it is great to see so many young kids coming out and supporting the event.
"There is a whole mixture of bikes - there's even a couple of tricycles out there which is pretty interesting," he said.
Organiser Annette How said it was great to have support from Staff, who won gold for Britain in the team sprint event in Beijing last year.
"Leukaemia Research has been organising bikeathons for 20 years," she said.
"It is now one of our signatures for raising money."