Prime Minister David Cameron kept a bar-room pledge to allow a group of fundraisers to begin their bike ride from Downing Street.
More than 30 cyclists set out from 10 Downing Street on the Mike Ride, in aid of Katharine House Hospice, in Adderbury, and Oxfordshire Association for the Blind on Friday, finishing in Chadlington.
The cyclists had taken part in previous rides from The Tite Inn, Chadlington.
Tite Inn landlord Mike Willis raised thousands of pounds for charity but died in 2010 after a three-year battle with cancer, and the ride was named in his honour.
Mr Cameron took part in several of the earlier events and said if he ever became Prime Minister, the 120-mile ride could start from Downing Street.
He said: “I am a big supporter of the fundraising efforts of Mike’s family and friends. I have fond memories of Mike.
“All ages have taken part in this special remembrance, and I know Mike would have been truly honoured.”
Among the riders were Mr Willis’ daughters, Genevieve and Nicola, and three cheers were raised for him before the two-day ride set off.
Event organiser Richard Greaves said: “All the riders should be proud of themselves.
“Their effort has raised over £10,000 for two very worthwhile charities, both close to Mike’s heart.
“It was particularly special to be riding in memory of Mike.”
To contribute, visit justgiving.com/nicola-willis-is-doing-the-mikeride or justgiving.com/Genevieveridesabike