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"I crashed heavily on the first moto [race] of day two which was really sore. The track was really well prepared and there was some awesome racing," he said.
Karepa is benefiting from the coaching and influence of Tauranga BMX Club's 2012 Olympian Kurt Pickard and has been selected to ride with Pickard in the six-rider Haro team.
The vastly experienced New Zealand rep Phillip Milburn says the extra work he put in before Rangiora paid off for him.
I went there with only one thing on my mind - to be number one.
"I trained very hard for six weeks leading up even through Christmas and New Year. I had good support in training by some club members," Milburn said.
"I went there with only one thing on my mind - to be number one. Before the final I just focused on my gate and put everything into those first five pedals. There were four or five of us that could have won so I knew that I had to ride my best race."
BMX NZ executive officer Dion Earnest says it is great to see kids out about on BMX bikes and even better to see them excel.
"Karepa is a junior athlete at the top of his sport and he constantly competes to be best in New Zealand in his age group. This is a busy year with the Oceania Championship and an early national championships. It's all focus and speed with racing every weekend till the BMX New Zealand Nationals at Easter," Earnest said.
"The Tauranga club is a great club with a great facility and a perfect place to grow a rider's skills and speed.
"With a great facility and such a good club environment we hope to see more great BMXers like Karepa from the club in the future."
Tauranga BMX Club hosts a BMX NZ National Qualifying event on February 14 at their excellent Cambridge Road venue, with the public welcome to attend to see some top-class racing and the best of Tauranga's riders in action.