The family of a great-grandfather killed shortly after he was given the all-clear from cancer have paid tribute to his "wisdom, wit and charm".
Donald Lock, 79, was stabbed repeatedly in an apparent road rage attack after a minor crash with another car.
The driver got out of the other car and fatally stabbed the pensioner before driving away, Sussex Police said.
Today members of Mr Lock's tearful family hugged each other for support as they told of their sadness at his death, and thanked members of the public who battled to save his life.
His voice cracking with emotion, Mr Lock's son Andrew said: "On Thursday evening dad was taken from us in what can only be described as an horrific and unprovoked attack.
"Our whole family are absolutely devastated with the loss of someone who can only be described as gentle, kind and loving."
He added: "The whole family are incredibly overwhelmed with all the messages of sympathy and support, the sheer volume of tributes on the various social media sites, and people even changing their profile pictures to a picture of dad.
"To the people who tried their best to help dad at the scene, we are deeply grateful for what they did, and know they did all that they could. We can only say thank you to you, and they are very much appreciated."
He said the family faces the "unenviable process" of facing the grief and moving on.
He said the family wants to "remember dad for the fantastic person he was – full of wisdom, full of wit, always calm. Always supportive, the perfect role model, and full of charm. Don, dad, granddad and great-granddad, the best."
Mr Lock was knifed repeatedly following the minor crash on the A24 at Findon, near Worthing, West Sussex, on Thursday evening. He died at the scene.
Married for 55 years, he was a veteran member of the Worthing Excelsior Cycling Club.
His family said he had recently been given the all-clear from cancer and was due to become a great grandfather for the sixth time.
Wearing the blue cycling jersey of the club, Mr Lock said his father was itching to get back to competitive cycling after returning to fitness.
He said: "As has already been said and stated, dad had recently been given the all-clear from prostate cancer, medication stopped and energy returning, and he even mooted the idea of doing a race with me later in the year.
"Although a few days later he did change his mind, as he realised he was probably being a bit optimistic, and probably concerned with how keen I was about doing the race."
He told of how his parents had been looking forward to going on a cruise next month before heading to Scotland for a holiday.
He raised a warm chuckle from his family as he recounted his father's adventurous streak – travelling around the world and even riding ostriches.
He said: "Over recent years we have joked with mum and dad about their holidays, suggesting they let us know when they are at home rather than when they are away.
"They have travelled to all parts of the world over the last 20 or so years. They have often done things that people 20 years younger would think twice about – walking over the Sydney Harbour Bridge, jet boat rides, even riding ostriches.
"Mum and dad were due to go on a cruise down the Rhine next month and then a few weeks later to their beloved Kentallen lodges near Glencoe in Scotland, a place that holds many memories for both of them."
A 34-year-old man from Worthing is being questioned on suspicion of murder after he was arrested by armed officers 18 hours after the attack.
Police were this morning granted further time to question him, and have until midnight tomorrow to charge or release him.
Sussex Police said they had seized a knife which has been sent for forensic examination in connection with the murder inquiry.
The senior investigating officer, Detective Chief Inspector Paul Rymarz of the Surrey and Sussex Major Crime Team, said: "Mr Lock was the victim of a violent, unprovoked attack that he had no chance to defend himself against."
He said a "significant number" of officers have been deployed to probe the murder, and urged anyone with information to call 101 quoting Operation Wise, email 101@sussex.pnn.police.uk or call Crimestoppers anonymously on 0800 555111.
Mr Lock, known as Don, leaves son Andrew, daughter Sandra, four grandchildren, and five great-grandchildren, with the sixth great-grandchild due later this year. The keen Brighton and Hove Albion football fan had lived in Worthing for 55 years.
A stream of family and friends have left floral tributes at the scene of the murder.