A Rotorua man who did a U-turn into the path of a Harley Davidson didn't see it due to an "optical illusion", a court has heard.

Richard Ian Jacobs, 61, was sentenced in the Rotorua District Court yesterday having pleaded guilty last month to two counts of careless driving causing injury, one of failing to stop and ascertain injury and one of careless driving. The collision with the bike, which injured its two riders, happened on December 20 on Dalbeth Rd, Hamurana.

Judge Chris McGuire disqualified Jacobs from driving for six months and ordered him to pay $3000 reparation - on top of the $5000 he had already voluntarily paid the victims.

Jacobs was driving west about 5pm when he pulled over to the left then attempted a U-turn, without indicating or checking that the road was clear, and collided with the Harley Davidson.

He drove on with his damaged front wheel at such an obscure angle it left a continuous skid mark on the road for 3km, crossing the centre line a number of times.

The male rider suffered ligament damage and severe swelling to his left leg, while his female passenger's left tibia was broken.

Defence lawyer Tim Braithwaite said Jacobs had since "grilled himself" about how it happened.

"He describes himself as a cautious driver usually."

Mr Braithwaite said Jacobs had concluded he must have mistaken the approaching bike's headlights for those of a car in the distance.

"It's an optical illusion."

The crash had affected Jacobs financially and emotionally and he had lost about $20,000 because of his inability to work in Australia while the case was before the courts, Mr Braithwaite said.

Jacobs could pay the extra $3000 reparation but would have to go into debt, he said.

Jacobs addressed the judge, saying at his age and with a shoulder injury it was difficult to get work as a builder.

"Please don't be under the illusion that it's easy for me at all," he said.

The judge replied "no it isn't".

"But it hasn't been easy for the [victims] either. They are the innocent parties here."

In determining sentence, Judge McGuire noted Jacobs' otherwise unblemished record.

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