Police said the rider was now in a stable condition and the Serious Crash Unit was investigating.
RNZ was unable to confirm if the rider was licensed or wearing a helmet, but it is understood the bike was unregistered and unwarranted.
That same day, Senior Sergeant Clem Armstrong, of Northland police, had issued a stark warning about the dangers of dirt bikes on urban streets.
He said the problem was particularly bad in Kaikohe and Whangārei, but many places in Northland – and around the country – were affected.
Armstrong was especially concerned about a trend of people taking young children joyriding on city streets without helmets or protective clothing, on bikes that often had poor brakes and bald tyres.
The danger had been highlighted by the severe facial injuries suffered by a 3-year-old boy in a dirt bike crash in Kaikohe.
Armstrong said the boy’s 22-year-old father had been charged with driving and child welfare offences, and was now going through the courts.
RNZ understands the child’s injuries included a broken jaw and facial lacerations.
Armstrong said the riders showed no consideration for children or other road users.
“It’s just a huge safety concern for us. I’ve seen first-hand people who have been seriously hurt, and the absolute last thing we want is for somebody to lose their life as a result of this sort of stuff,” he said.
Monday’s crash in Whangārei was on the same stretch of road – Otaika Rd or State Highway 1 – where a 29-year-old man was critically injured when his dirt bike and a car collided last March.
He died later in hospital.
A Kaikohe resident, who did not want to be named for fear of retribution, said he often saw people tearing up and down his street on dirt bikes – sometimes taking small children for joyrides.
Thinking about what would happen in a crash made him “deeply, deeply anxious”.
“Parents, mothers and fathers alike, will take a little, tiny baby for a ride down the street, and the child is sitting in front of them with no restraints … They have no idea what would happen if they suddenly hit something. They would just go flying like a bag of cement and have to be scraped off the road 20 metres ahead.”
He said that the crash involving the 3-year-old had not stopped people from taking children for joyrides.