The trial was told that Joy had run to her "bent and buckled" sister, but was directed by a doctor to tend to Berridge and Georgina Carson-Waihi.
Judge Robert Spear convicted Berridge on both charges, but discharged him without criminal penalty after Berridge undertook to make emotional harm payments totalling $10,000 to Robyn's family.
Berridge will also make a payment of $1000 to Carson-Waihi. He was disqualified from driving for six months.
The court was told during the trial that Berridge had been stationary on the side of SH51 near the Awatoto intersection, before pulling out into the northbound lane. Whether there was a "T-bone" collision caused by Berridge attempting a U-turn or whether Peters' bike struck Berridge's from behind was in dispute between the prosecution and defence.
However, defence counsel Alistair Haskett said on Thursday that Berridge, who testified he had no memory of the crash, accepted after hearing the evidence that he was responsible for it.
Judge Spear said there was no criminal culpability in the case needing to be addressed.
He said it was a mistake with "horrible consequences", made by a man with a previously good record of riding motorcycles.
"The convictions themselves will be a penalty."
Joy said she was pleased she was able to read out her victim impact statement, in court.
"It was hard to write it. I had to start again many times as the paper kept getting wet.
"Then I stood up in the courtroom, by myself, in the middle of no-man's land, and I read it out. I started out a bit shaky but the detective who was supporting me said 'you've got this'.
"I was looking at Berridge. He had shown no emotion throughout the trial. I knew he wasn't going to prison ... I get it, he didn't wake up that morning planning to cause someone's death. It was an accident.
"But I wanted him to know Robyn was didn't just exist - she had a life. I wanted him to know how loved she was, and to show some emotion."
Joy had been told she didn't have to attend every day of the trial, "but there was no way in hell I was staying away. I was there for my sister. It was mentally draining, and it sucks she's not here any more, but we have to move through it, keep going."
Robyn and Joy had both grown up riding motorcycles, starting aged 12 on trail bikes on the beach or in the family's paddocks, then graduating on to road bikes.
Robyn even took to the racetrack as a swinger on sidecars.
If the sisters weren't on a bike they were on a horse ... Robyn's other passion, which included trekking, riding at the beach and along the Waipawa River and even breaking in a pony and giving cart rides at the beach, at market days and Waipawa's Duck Day festival.
Her other love, says Joy, "was a good party".
The memorial to Robyn at the base of a Norfolk pine tree on Napier's Marine Parade bears witness to her loves: A cross fabricated from horse-shoes that had been worn by her horses past and present, a pendant representing the Iron Sisters motorcycle club, and a bra or two - memories of a good night out when she was challenged to enter a wet T-shirt contest, and she won.
"We had a lot of laughs. Most people in Waipawa knew Robyn, from seeing us out riding to seeing her in her role at Downer. She had connections throughout the community. her funeral was huge.
"As I have told my kids - it sucks that she isn't here, that I won't get a text from her saying 'let's go!' But we're still moving forward, and we're still allowed to smile."
