If they hadn't been found, the bodies could have remained there for weeks or more, he said.
"It was pretty gross. I think the woman had her throat slit and it was not very nice.''
The charity event had to be shut down as a result.
"It's not really what you want to do when you're running a fund raiser,'' he said.
The bodies were found about 40 minutes' drive from the Waimate township.
"It's a small place and these sort of things don't happen very often.''
Waimate Main School board of trustees chairman Tony McKenzie was taking part in the charity event but did not see the bodies.
He says the discovery came as a shock.
"We were having such a good day with the trail bike ride and we had such a good turnout of riders. It doesn't leave a very good feeling now.''
The event had been cancelled immediately.
There were many rumours circulating about what had happened and it was hard to know what was true.
"The police have it all cordoned off so other than that we don't know anything at this stage.''
Police said they had launched an investigation following the discovery.
"Due to the isolated location efforts are still being made to reconstruct what has happened,'' a statement said.
Police were yet to identify the bodies.
The Oamaru Mail understands the bodies were found in the Waihaorunga area, an expanse of rolling, forested terrain which groups are sometimes permitted access to for events such as charity rides.