Kirill Koninin always wore a helmet when he went out on his bike - but for some reason on December 23 he made the fatal decision to leave it at home.
Hours later he had suffered a catastrophic head injury and on Christmas Eve his family made the heartbreaking decision to turn the 17-year-old's life support off.
Now they are speaking out in a bid to prevent future tragedies and are urging young people to always - always - wear a helmet.
Kirill's cousin Ilya Zharenikov said the teen was riding his BMX at a skate park in Albany in North Auckland when he fell and hit his head.
He was knocked out and then lapsed in and out of consciousness before an ambulance arrived and rushed him to hospital for emergency surgery.
It was hoped the operation could save his life - but afterwards there were no signs of any brain activity.
"His brain just was not responding," said Zharenikov.
"The family decided to disconnect him from his life support … it was a really emotional
few days for us.
"His parents are devastated - it's not easy for us, but for them I cannot imagine what this is like.
"I have three kids myself and I cannot ever imagine the pain I would feel if this happened."
Kirill died at 1.30pm on Christmas Eve surrounded by his family including his parents Vladimir and Oxana and his brother Stas, 24.
"Our star has gone out. What is the meaning of life now," his father posted on Facebook.
The Long Bay College student was farewelled at a funeral on December 29.
Zharenikov set up a Givealittle page to help the family out as they came to terms with their loss.
He said Kirill's friends suggested it.
"He had so many friends," Zharenikov told the Herald.
"He was so fun to be around, he was very kind.
"My oldest son is 9 and there is a big age difference but Kirill would always come and
spend time with my son … they had a very strong connection and that was something very special to me.
"Kirill was like a hero for my son - someone he would always want to be like."
Kirill was born in Russia and his family moved to New Zealand about seven years ago.
"He was really a little Kiwi," said Zharenikov.
"He had lost his Russian accent mostly, he was definitely becoming more Kiwi."
In Russia, Kirill was a champion mountain skier and when he came to New Zealand his passion for sport grew.
He started martial arts, loved BMX riding and swimming - where he won three gold medals competing - and represented his school at basketball.
"He was very special," said Zharenikov.
"He had so much potential… he could have represented New Zealand at sport… we have lost that."
Kirill's parents believed that if he had been wearing a helmet he may have survived the fall from his bike.
"They have a safety warning," said Zharenikov.
"On that particular day, for whatever reason, Kirill didn't take his helmet with him.
"He usually did, but on that day… Who knows, perhaps we would still have Kirill if he was wearing a helmet.
"We want to pass on the message that safety is so important and it might be being taken too lightly, especially at skate parks.
"It seems like there's a trend with people not wearing them but it is not cool to not wear a helmet - they are very important and we want to encourage kids to wear them always."
Zharenikov said Kirill's parents hoped to speak to Auckland Council about a memorial bench in his name at the park.
They wanted people to remember their son, what they lost and the potential he had.
In New Zealand it is illegal to ride a bike on the road without a helmet.
A police spokeswoman told the Herald helmets were a legal requirement at all times while riding a bicycle, "no matter where you are riding".
Failure to wear a helmet can result in a $55 fine.
Cycling Action Network spokesman Patrick Morgan said the news of Kirill's death was "terrible".
"It's distressing to hear of the crash... it's sad news," he said.
"Our condolences got out to the family, it's the worst news you could expect."
Morgan said generally New Zealand had very good compliance for helmet wearing - about 90 per cent of people wore them since they became a legal requirement 27 years ago.
"Our advice is simple: ride within your limits, make sure your bike is safe to ride and follow the law."
Police did not attend the crash and could not comment.
Kirill's death has been referred to the Coroner.
Be safe on a bike - helmet rules, safety
Wearing an approved safety helmet dramatically reduces the risk of a skull fracture if your head hits an object or the road, which is why the law requires you to wear one.
A helmet also reduces your chance of getting concussion and protects your head from cuts and scrapes.
A cycle helmet must:
• meet an approved standard
• be securely fastened