Earlier the junior women's race over five laps followed similar lines with 38 riders contesting the bunch sprint won by Garner with Sophie Williamson, young sister of James, finishing with a creditable 18th place.
It has been a strong campaign for the 17-year-old from Alexandra, who won a bronze at the recent junior track world championships.
It was not such good fortunes for her team-mate Georgia Williams (Auckland), who was involved in a crash early in the race and required medical assistance. She was later taken to hospital as a precautionary measure.
"The racing went largely to what we all thought would happen today," BikeNZ director sportif Andy Reid said. "It is a fast and flowing circuit with few opportunities for a significant break to stick.
"The junior women averaged over 40kph, which gives some idea of the speeds here and it really suits an out-and-out sprinter which is not really to our strengths.
"Sophie was impressive in the junior girls and got herself into an excellent position. It was a striking ride from her."
The elite women's race will be contested overnight, but the course isn't expected to suit Linda Villumsen who won silver in the women's time trial earlier in the week. The men's race is set for Monday (NZT) with the BikeNZ team comprising Jack Bauer and pro tour sprinters Julian Dean and Greg Henderson.
RESULTS:
Junior women's road race (70km): Lucy Garner (GBR) 1:46.17, 1; Jessy Druyts (BEL) same time, 2; Christina Siggaard (DEN) same time, 3. Also New Zealanders: Sophie Williamson same time, 18; Georgia Williams dnf.
Under-23 men (168km): Amaud Demare (FRA) 3:52.16, 1; Adrien Petit (FRA) same time, 2; Andrew Penn (GBR) same time, 3. Also New Zealanders: Tom David same time, 80; James Williamson at 1:52, 112; George Bennett at 9:34, 134.