Gardner won the under-19 points race at the Oceania track championships in Brisbane on Sunday night.
The powerful rider, who has also had success on the road, produced an excellent all-round display in the hotly contested race.
He showed his strength with a daring attack late in the race to lap the field for the 20 bonus points.
A final burst gave him the additional eight points for second to claim the overall honours from team-mate Matthew Davidson.
Gardner then joined Kane Foster, Marshall Erwood and Magnus Jamieson to top qualifying in the under-19 4000m team pursuit. They clocked 4min 12.540sec in qualifying, just 0.3sec ahead of Australia.
The Australian team produced a world-class time of 4min 8.097sec to win the final ahead of the Kiwi quartet, who had to settle for silver 8sec back.
There were also podium performances from New Zealand riders Ellesse Andrews, Tom Sexton and Emily Shearman in elite racing on the third day of the championships.
All three gained silver medals in the keirin and omnium competitions in some close racing at the Anna Meares Velodrome.
The elite women’s keirin competition began with Andrews winning her heat but Rebecca Petch and Olivia King forced into the repechage, where both went through.
Andrews dominated her semifinal with King in second for both to move through to the final, while Petch produced an impressive ride to win the second semifinal.
Andrews, who led into the last lap of the final, was pipped on the line by Australian Kristina Clonan with King fifth and Petch sixth.
Keegan Hornblow out-kicked five Australians to win the 10km scratch race, first discipline of the omnium, with George Jackson seventh and Sexton 13th.
The Kiwi men were strong in the tempo race, the second omnium discipline, Sexton winning after lapping the field, and Jackson third.
Jackson claimed the elimination race with a clever display from the front of the race, and Sexton was fourth.
It left Jackson in third place, six points behind the two joint leaders from Australia with Sexton a further eight points adrift going into the deciding points race.
Sexton was outstanding in the points race, gaining a lap and picking up useful points but Australian John Carter also gained a lap before winning the double points final sprint to claim the victory on 136 points.
Sexton moved through the field for second on 129 with Hornblow sixth and Jackson seventh.
Australia’s Chloe Moran won the scratch race ahead of Kiwis Shearman and Sami Donnelly in the women’s omnium.
Shearman bounced back to win the tempo race with nine points ahead of team-mates Rylee McMullen and Donnelly on five and four points respectively.
Moran claimed the elimination race ahead of McMullen — Donnelly was sixth and Shearman seventh — to open a 10-point lead on Donnelly and 12 on Shearman going into the deciding event.
The Australian held her advantage in a tightly run points race, where none of the leaders could lap the field. Moran managed 16 points to finish on 130, comfortably clear of Shearman in second with Donnelly fourth, just two points off the podium.
Sam Dakin and Callum Saunders both finished second in their heats of the elite men’s keirin to progress to the semifinal.
Dakin, in his first competitive ride after a heavy fall in the keirin final at the Nations Cup, managed third place behind Australians Matthew Richardson and Sam Gallagher to move to the final.
Saunders achieved the same behind Aussies James Brister and Mathew Glaetzer to make the final, where the Australians dominated and Richardson won.
