With exhaustion setting in, the attrition rate was high about a quarter of the field electing to bypass the turn back on to Waimutu Rd for the third time and head back to the finish early.
At the top of the Waimutu climb for the third time, Goode and his surviving co-marker Adrian Pettit caught the remnants of the break bunch, then set about chasing down the leaders.
They achieved their goal on Tutaenui Rd as Goode then attacked hard on the first climb after the turn on to Makahou Rd, dragging with him Pettit, Cameron and Forrest. This quartet applied more heat as the race splintered under pressure behind them, and built an unassailable lead with about 20km to travel.
With a headwind to contend with, the pace dropped for the final five kilometres back to the finish.
Showing youthful confidence, Goode launched his finishing sprint well short of the line and with a great show of defiance clung on for a very hard-earned half-bike length win over fellow youngster Cameron.
Cameron got her second wind inside the final 100m and was coming hard at Goode on the line.
Close behind in third was Forrest, who had ridden out of his skin for his placing, just ahead of Pettit in fourth after doing a huge amount of work during the running.
The leading group was well clear of an exhausted Tucker, home fifth, with a further gap back to Forrester rounding out the top six.
The remainder of the much reduced field limped home at intervals thereafter.
The 11 B and C-grade riders combined to compete around the same course, albeit over just two laps of the Waimutu Rd circuit.
Experienced Manawatu visitor Megan Blatchford-Peck streaked clear after the second climb and then steadily extended her lead to come home a convincing winner.
Blatchford-Peck is building up for a crack at the club national championships in Queenstown in May and is certain to be competitive in her age group.
Alison Richards was unable to foot it with the winner but rode very well to finish second, similarly well clear of Stu Bruce in third, who battled severe cramp in the latter stages.
Jane Winchcombe and Kathleen Murphy finished together in fourth and fifth respectively.
Murray McDonald was the best of the C-graders finishing in a time of 2.34.35, with a gap back to Debbie Cain and Jim Callaghan.
Results:
A Grade, 100km group handicap: Matt Goode (fastest time 2.57.05) 1, Cassie Cameron 2, Paul Forrest 3.
B and C Grade, 70km mass start: Megan Blatchford-Peck (fastest time 2.21.25) 1, Alison Richards 2, Stu Bruce 3.