As Grant started to pull back out into the traffic, he struck the victim, causing the cyclist to slap the van with his hand.
An agitated Grant got out of the van, approached the victim, then punched him in the left side of the face with his right hand.
The victim, who fell to the ground, suffered loose teeth, bruising and bleeding to his lips and teeth.
Grant told police he had "just lost it".
His lawyer Viv Winiata told Judge Christopher Harding that his client was willing to take part in a restorative justice meeting but the victim declined the offer.
Winiata said although the victim's claim for financial losses could be covered by ACC through earnings-related compensation.
But Grant, who was remorseful, was prepared to pay for actual damages and emotional harm reparation, he said.
Judge Harding told Grant that the victim impact statement confirmed the complainant suffered ongoing effects but no lasting injuries.
"This was clearly an out-of-character effort on your part and absolutely should not have happened."
Judge Harding said "king-hits" of this kind could render some people unconscious, and frequently attracted sentences of up to 18 months' imprisonment.
"You did not render the victim unconscious but for offending at this level a fine would not be an adequate response."
Judge Harding sentenced Grant to 60 hours' community work and ordered him to pay the victim $262 reparation and a $750 for emotional harm.
Grant's victim, who was seated in the public gallery during most of the proceedings, declined to comment when approached by the Bay of Plenty Times outside court.