"That was so hard," Horgan said. "I thought that four minutes was about as much as we could let them go. When we heard it was 5:30 it meant we had to go and much earlier than I had wanted. It took everything to catch them."
Horgan said he was unsure of his form coming into the event after just returning from the Tour of Korea where he did not perform as well as he wanted in the demanding conditions.
"I just had to dig deep today. I had to put my head down and go for it. But it's a great way to finish this block. I think I need a break now and then reset myself for the Tour of Southland later in the year and then January's elite championships."
Binney held on to get reward for his brave frontrunning to take the under-23 honours.
Earlier former top rating English professional Dave Mann (Hamilton) celebrated his rise to the 50-54 years ranks with a superb sprint victory in his age group.
Results:
Masters 50-54, 87km: Dave Mann (Hamilton City) 2:15:40, 1; Andrew Morrissey (Counties Manukau) 2:15:40, 2; Jim McMurray (Forestland Wheelers) 2:15:40, 3.
Elite Men, 176km: Sam Horgan (Pegasus) 4:27:13, 1; Dan Warren (Ramblers Cycling Club Inc) same time, 2; Andrew Hagan (Port Nicholson Poneke Cycling Club) same time, 3.
Under-23, 176km: Simon Binney (Tauranga) 4:28:00, 1; Matthew Markby (Marsden Wheelers) 4:28:46, 2; James McCoy (Papanui) same time, 3.
Paracyclist Men 58km
C2: Stephen Hills (Cycling New Plymouth) 2:46:35, 1. C3: Nathan Smith (Cycling New Plymouth) 2:25:25, 1. C4: Craig Hill (Ramblers) 2:34:15, 1.