Whitehead claimed his role was limited to punching the victim in the face and taking his bag. But Judge Cathcart said the agreed summary of facts showed all four men equally culpable in law either as principles or parties.
"You might have given an explanation that places your role at a lower level of seriousness but the facts before me suggest an equally culpable inference, which is what I draw," Cathcart said.
The incident happened on January 23.
The group — all either patched members or associates of the Black Power gang — were travelling back to the Gisborne region after a gang meeting in Auckland.
They were all intoxicated when they confronted the victim who was cycling near the intersection of Devonport Rd and 15th Avenue, on his way to feed cats that were in his care.
The group knocked him off his bike, punched and kicked him causing his dentures to break in four pieces, and rendered him unconscious.
They stole his backpack containing pet food, a torch, and other miscellaneous personal items then fled in a ute parked in a nearby car park.
Two other cyclists went to the unconscious man's aid.
Cathcart said the victim impact statement was concerning reading. The man suffered facial bruising including a black eye and bruising to his midriff.
The incident had a financial impact on him. He needed new dentures and went without them for about a month. His bike was also damaged.
"Ultimately this case is very close to aggravated robbery… and if that charge had been levelled the starting point would have been much higher and I bear that in mind when dealing with the overall start," Cathcart said.
He fixed a starting point for the assault with intent to injure at 17 months, saying this offence fitted within the top of band two or the beginning of band three of a tariff case. Incorporating the theft charge, the judge reached an overall global start of 20 months.
Whitehead received a full 25 per cent (four months) discount for his guilty pleas and a total of three months discount for other factors — his lack of previous similar offending (otherwise good character), remorse and willingness to attend restorative justice, and favourable personal circumstances including his employment as traversed in a pre-sentence report.
While willing to convert the sentence to home detention, the judge rejected a recommendation for community detention coupled with supervision, which he said would be insufficient to mark the offending.