Her 2015 was mainly dedicated to getting healthy after she tore the ACL ligament in her left knee in March, but now Duncan (19) is about to launch herself full-on into her motocross career.

She does not do things by halves.

After a race at New Plymouth this month, she will travel to Qatar for the first round of the women's world championship, involving about 40 riders - the best female motocross riders in the world.

Duncan is looking forward to the challenge.

Being in the top echelon of her sport is something Duncan has always chased, and usually found.

When she was 12 and 13, she was beating boys three years older at national championships.

They really were eating her dust.

"Ever since I got on the bike when I was 7, I have always wanted to be the best I can be.

"I want to be a world champion,'' she said.

"When I was little, I had that attitude of wanting to be the best, wanting to win.''

But Duncan has had to endure a fair bit of pain to pursue that dream.

She had two knee operations in 2011 and then her latest setback last March.

"I knew straight away what had happened. I was just passing a basketball around before I was to go into the gym and something felt funny.

"It had happened before, so I knew what it was.''

She was flown to Auckland within a couple of weeks for surgery on her knee by Dr Mat Brick and then began the long process of rehabilitation.

"I did my exercises pretty much every day. Had the weekend off, but every day it was just about getting fit again.''

She got back on the bike in late October, and it was as if the two had never been apart.

"I thought I would be a bit nervous getting back on but it just felt like home. But my bike fitness was terrible.''

Coached and mentored now by former world No2 rider Josh Coppins, of Motueka, Duncan has been spending a lot of time on the bike but said it was about "quality not quantity''.

It is not easy.

Motocross is a hard, physical sport.

Her 59kg frame has to manoeuvre her Yamaha 250cc bike, which weighs more than 110kg, around a tight and tough dirt circuit.

Three knee operations have taught her to appreciate everything.

"I've got the most supportive parents, the best sponsors, the best set-up. Now it is just up to me. The expectations are always there but I wouldn't want it any other way.''