Fastest time of 1.04.30 went to Southland scratch rider Corbin Strong.
Jacob Chetwin (off 2.5 minutes) won the Under 15 section, covering the one lap circuit in 28.28 minutes. Josh Rowe was second at three seconds and Stirling Jarnell third.
An ecstatic Chapman said his win over three laps was unexpected.
"My goal for the day was to stay with my group as long as I could, anything more would be a bonus.
"It's awesome to win a prestigious event at the club, and hugely motivating for me personally. It was good to get a win for the big boys – we'll take them where we can."
Chapman started with "seven or eight" riders in his group. He had been dropped on the first lap in the last handicap race, so set himself the goal of staying in the group until the second lap at least.
"Everyone worked well together, keeping each other honest and doing their share of the work," he said.
"We were four minutes from the front at the end of lap one. By the end of lap two, we were one minute 30 seconds from the front.
"We caught the group ahead of us, and then the front group just before Parawera Rd."
Chapman said the larger bunch stayed together, with a core group of siz-eight riders pulling turns on the front.
"When we reached Puahue Rd, I was positioned well back in the bunch.
"I wanted to stay upright so decided to stay put. Over the undulation some gaps in the bunch appeared, and I was able to move up the group.
"When we hit the last rise, I couldn't see a clear path through at first. The riders in front of me moved right, Andrew Harrison powered off the front and I decided to have a dig (knowing that hills and gravity are not my forte).
"I managed to get up and past Andrew's wheel, then put my head down and kept pushing as hard as I could to the line."
Last year, in only his second serious season as a club member, Chapman won the D grade club championship at Kōrakonui, as well as winning one of the races in the winter series at Goodwood.
Chapman said his dad, Alan, is passionate about cycling, and has always been a source of inspiration and encouragement for him. His brother Steve is hugely supportive as well.
"I started racing with the Te Awamutu club about two years ago, I love the competitive and tactical aspects of this part of the sport – being able to watch and interact with the world class athletes we have in our club is exciting/inspirational as well. It really is a club for everyone."
Chapman has now set his sights on racing as part of the Team Speed Theory Category 5 team in the Dynamo Team Series, starting in Cambridge on September 20 with a team time trial and road race. He is also riding the Karāpiro 100km Flyer on October 3, and the Lake Taupō Cycle Challenge on November 14.
Week nine's A grade race at Ngāhinapōuri was won by Alex Heaney on Sunday in a sprint finish from Mark Stewart (Great Britain), James Harvey (TASC), Theo Gilbertson (CMC), Adrian Hegyvary (USA) and Daniel Bridgwater (TASC).
The final race in the 10 week winter series will be contested at Goodwood in Cambridge. The race includes the infamous Maungakawa hill for A-D grade.
