Bad driving and lack of communication over road gritting contributed to Britain's "worst cycling disaster," a coroner has said.
Thomas Harland, 14, Maurice Broadbent, 61, Dave Horrocks, 55, and Wayne Wilkes, 42, died while on a practice ride near Abergele, on 8 January, 2006.
In a damning statement, the coroner said police and officials had been "most unprofessional".
The jury ruled out accidental death and returned a narrative verdict.
Marking the end of an emotional and dramatic three-week hearing at Abergele, north-east Wales coroner John Hughes said: "The evidence shows classic signs that Robert Harris was driving without due care and attention and to his credit he admitted his responsibility in going too fast.
"I fail to understand why no proceedings were brought against him."
On a failure to grit roads after calls had been made alerting officials of ice, Mr Hughes said the North Wales Police control room "needs a rethink from top to bottom in their transmission of information and briefings".
"I sat here biting my tongue during the inquest of this most unprofessional state of affairs and I will be writing to the chief constable recommending a fundamental examination of the way they receive and disseminate information and a general re-training of those involved."
Mr Hughes added: "It seems there was [a] Berlin Wall between the counties of Conwy and Denbighshire, but the weather takes no account of lines on maps.
Police officers examining the crash scene near Abergele
"Some steps have been taken to change things, but it's a pity it's taken four lives to get this movement."
His comments came after the inquest jury highlighted failures by North Wales Police and Denbighshire and Conwy council officials.
In a narrative verdict - which delivers factual statements on events leading to the deaths - the jury decided the vehicle was being driven in an inappropriate manner and that there was a "serious lack of communication" between police and local authorities.
The cyclists had set out on a 60-mile trip between Great Orme and Llanrwst, in what they believed was fine weather, in pairs and wearing helmets.
Around 1000 GMT that day the Rhyl Cycling Club members wound their way along the A547 Rhuddlan Road.
Some time after, four members of the Sunday club lay fatally injured.
Motorist Robert Harris, 47, had been travelling in the opposite direction in his Toyota Corolla on his way to work as a security guard for B&Q. His car skidded on ice and span out of control, crashing into the cyclists.
The jury heard from cycling club member Jonathan Harland, who had been riding alongside his son Thomas, seconds before the teenager was killed.
While he said he initially felt no anger towards the driver, a statement read to the court on his behalf told how he felt "for many months nothing but anger towards the driver who killed my son and three of my best friends".
A week later, the inquest heard from motorist Mr Harris. He said he had been "very possibly" driving too fast and that he often wished he had died instead.
The inquest heard that he constantly recalled the tragedy and "did not set out intending to harm or even upset anyone".
In August last year, Mr Harris was fined £180 with £35 costs and given six points on his licence after admitting having defective tyres - found not to be a factor in the crash.
Other crucial evidence centred around the issue of road gritting. The jury heard how police had informed Conwy Council's highways department that roads needed treating.
This came after a motorist complained of skidding on a bridge in the Towyn area earlier that morning.
Inspector Jane Banham told the hearing she expected the council to review the state of all roads in the area following that call.
She said an officer asked her a short time later for parts of the A547 near the crash scene also to be gritted due to problems with ice.
But, she told the inquest, she did not contact Conwy Council with that specific request.
Responding to the coroner's comments, Conwy Council said procedures had already been reviewed and measures were under way to improve communication.
A police statement read: "North Wales Police will now consider the findings and the recommendations carefully and at length."