The Dunedin event is the most difficult in the country and calls for steady nerves and a mixture of caution and bravery.
Nicoll (35) won because he showed his maturity and did not make mistakes. He also won the masters 1 title.
It was a close race. Nicoll beat former international downhill specialist Justin Leov (Canterbury) by 6sec.
Nicoll won the four-stage enduro event in 27min 57sec, from Canterbury riders Leov (28min 3sec) and Anton Cooper (28min 11sec). Ethan Glover (Dunedin) was fourth in 28min 36sec.
''It is often pretty tight like that among the professional riders overseas,'' Nicoll said.
It was not a surprise result because Nicoll finished eighth in this year's world enduro series. He has been riding since 1990 and has just returned to New Zealand after his second international racing season.
Nicoll does not have a professional contract yet but expects to be signed up before next year's international series.
''I was self-funded this year and beat many of the professional riders,'' he said.
He has done it the hard way over the last two years and now knows that he can foot it with the best enduro riders in the world. But getting funding will make it easier.
''I will be able to train properly, rather than working a full day and then trying to train as much as a pro rider.''
Nicoll grew up in Wellington and spent time racing in Nelson. His partner, Brydie Fahey, is studying medicine at the University of Otago and he has come to Dunedin to join her.
He races on circuits in Europe and North America and will base himself in Queenstown during the summer to prepare for the first round of the enduro world series in Chile in April.
Leov, a former top international downhill rider, was tempted back into the sport when the enduro world series started.
He crashed on the Pineapple Track on Saturday and lost 12sec to Cooper on that stage.
Cooper (Canterbury), the pre-race favourite, had a 9sec lead on the field before the final downhill stage from Signal Hill to Logan Park High School. But his chain came off near the bottom of the downhill and it proved costly when he lost 23sec on the field.
''If the race had finished at the bottom of the downhill I would only have lost 5sec,'' Cooper (19) said.
''I needed to pedal again and had to stop to put my chain back on. I was stuck and I lost a lot of time putting it back on. It cost me the overall win.''
Defending champion Tom Lamb (Dunedin) finished fourth in the men's section and sixth overall in 29min.
Defending champion Rosara Joseph (Wellington) comfortably won the women's race by 1min 16sec with her time of 33min 3sec.
Meg Bichard (Nelson) was second in 34min 19sec and Anja McDonald (Dunedin) third in 34min 36sec. McDonald was the top masters woman.
Joseph took time from Bichard on all four stages, the most telling being 25sec on the Flagstaff stage, from the Bull Pen to the Wakari car park, and a huge 42sec on the downhill stage from Signal Hill.
Joseph (31) has been racing overseas this year and has become more used to riding on rough and rocky enduro tracks.
''I felt more comfortable in the event this year compared to last year,'' she said.
She is concentrating on the enduro events and is not attempting to make New Zealand's cross-country team for the Commonwealth Games.
Joseph was in the United Kingdom for five years as a Rhodes Scholar at Oxford University and graduated in law. She works as a lawyer at Wellington when she is not racing overseas.
The first junior woman home was Shannon Hope (Dunedin) in 40min 23sec.
