A Cambridge businessman who opened the door of his ute without checking to see if any cyclists were riding past clipped a rider, sending the man crashing into the path of another ute that ran him over.

The cyclist - a Harrowfield man in his mid 40s - suffered horrific injuries, including a bad injury to his brain in spite of the fact he was wearing a helmet. His ribs were smashed and he had to have a metal plate inserted in his chest to hold them together.

The story of the fateful impact on Te Rapa Rd in Hamilton on March 5 was revealed at the sentencing of Mark Richard Terry, 51, in the Hamilton District Court on Thursday.

Terry had earlier pleaded guilty to a single charge of careless operation of a motor vehicle causing injury. It was a case of "vehicle operation" in its loosest sense, because at 1.30pm that day he had parked his Ford Ranger ute on the side of the road on the north-bound lane, between the cycle lane and the footpath.

It was at that moment that the cyclist rode out of Sunshine Ave and down Te Rapa Rd. He had just finished work and was heading home.

As well as his helmet, he was wearing a red singlet and a fluorescent orange backpack.

At the cyclist rode past the Ranger, Terry opened the door without checking if the the way was clear. The door hit the rider, who was thrown into the roadway.

The next second, as he lay on the tarseal, he was struck by a passing Volkswagen ute.

As the police summary of facts on the incident reveals, Terry initially told the police he was about to get out of his ute when he heard a loud bang, and saw a guy and a bike on the ground.

However Dashcam footage from the ute that struck the cyclist and CCTV footage from a nearby business showed that it was Terry who had hit the rider, causing him to fall off his bike.

When Terry was shown the footage, he said he did not remember opening the door. He said he did not realise it was he who had caused the crash, and if he had realised it he would have told the officer at the time.

In court, Terry's counsel Jess Tarrant applied for a discharge without conviction.

It was, as the court was told, being made partly on humanitarian grounds. Terry's wife was terminally ill with cancer and he had to support his young daughter and hold down his job as a heavy vehicle brake certifier, which required a lot of travel.

His family's dire situation meant he had not pursued a restorative justice conference with his victim prior to sentencing. Terry wanted to apologise to his victim and had plead guilty at the earliest opportunity.

He had also paid the victim $4750 in reparation, and he had a further $5250 that could be paid within seven days.

Tarrant said the accident was the result of "momentary inattention ... that could happen to any one of us."

Judge Kim Saunders had a victim impact statement from the victim and his partner which revealed that the night before the crash he had asked her to marry him.

He had lost about a month of his memory, and had spent an even longer time in hospital and a brain trauma unit in Auckland. He had lost weight, fitness and had developed a low tolerance to noise.

He had not been able to go back to work and, unable to drive, it appeared likely he would be losing his employment.

He also had no intention of ever getting back on his bike.

Terry had no previous convictions aside from a drink-drive in 1993, and Saunders said she would treat him as a first time offender.

He also had affidavits from his employer and colleagues that described him as "a big-hearted human being", "a man of integrity," "solid and dependable" and various other similar terms.

Judge Saunders deemed the degree of Terry's carelessness to be low to moderate - too high to warrant a discharge without conviction.

"The impact of your carelessness cannot be put to one side, she said.

"The consequences were tragic. They were terrible, and they will affect him for the rest of his life."

Given Terry's circumstances she chose not to disqualify him from driving. Instead, she ordered him to undertake 40 hours of community work, as well as pay his victim the full $10,000 in reparation.