"I really put it down for about 10 hard strokes and looked back and couldn't believe there was no-one there. Ali was awesome. I was on the inside and she held them up and dropped the pace at the start of the hill a little bit which was great for me.
"I was meant to be at graduation with all my friends today. But I have definitely been thinking about this for a long time. It means a lot."
Trotman was fourth in the national elite road championships and fifth overall and first New Zealander in the international Tour of New Zealand.
It was a good hit-out for the Olympic-bound track team, who mixed racing this week with training and major planning sessions before they head to the US to begin their concerted build-up for London.
Earlier Alexandra's Sophie Williamson edged out Wanganui's Cassie Cameron in a sprint finish to win the under-19 race over 87kms.
The pair, both medallists in last year's world junior track championships, are using the road to prepare towards this year's world event to be held on home turn in Invercargill in August.
"I love racing. I find it brings me up well," Williamson said. "That was pretty close, though.
"The road racing is a big part of the build up for me. I am pleased with my form this week which shows I have a good base."
Williamson heads to the US in June to race and train in Milwaukee and Pennsylvania before heading home for the world championships.
"The world championships are going to be so big. To race at home in a world championship in front of your family and friends is going to be so awesome."
Earlier former Commonwealth Games medallist Gordon McCauley edged out Auckland's Aaron Strong to win the masters 40-44 years race over 116kms, to reverse their result in the time trial earlier in the week.
The championships finish tomorrow with the senior men's race over 177kms.