Detectives are continuing to question a man suspected of killing a great-grandfather described as "kind and loving" by his devastated family.
Donald Lock, 79, was stabbed repeatedly in an apparent road rage attack shortly after being given the all-clear from cancer.
A 34-year-old man from Worthing is being questioned on suspicion of murder after the incident on the A24 at Findon, near Worthing, West Sussex, on Thursday evening.
Police have until midnight tonight to charge or release him.
Yesterday tearful members of Mr Lock's 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 said the family are "overwhelmed" at the outpouring of support they have received, and "deeply grateful" to members of the public who tried to save his father.
Wearing the blue cycling jersey of his father's Worthing Excelsior Cycling Club, Mr Lock 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 had been given the all-clear from prostate cancer and was due to become a great-grandfather for the sixth time.
A keen traveller, he had been looking forward to going on a cruise with his wife next month before heading to Scotland for a holiday.
His son 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."
Sussex Police said they had seized a knife and car which are being examined in connection with the murder inquiry.
Anyone with information is urged to call 101 quoting Operation Wise, email 101@sussex.pnn.police.uk or call Crimestoppers anonymously on 0800 555111.