Meeting with him once is like listening to a chemist talk about the periodic table.
Grey has ran four marathons and -- to the best of his knowledge -- at least a dozen mini-marathons.
"I have never started a race I have not finished," Grey said.
He also has a passion for bicycling, and on Saturday, he will take part in the Ride Across INdiana (RAIN) bicycle ride, an event sponsored by the Bloomington Bicycle Club.
Grey has competed in the 158-mile bicycle ride twice before. The ride begins at the state line in West Terre Haute and ends on U.S. 40 in Richmond.
The last time Grey rode in the race, he finished with a time of 10 hours and 25 minutes.
"I'm hoping to break 10 hours this time," Grey said Thursday.
And he believes the possibility of breaking the 10-hour mark is within reach.
Grey has been training solidly for nearly eight weeks for the event.
"You have to train," Grey said. "You'd be crazy to think you can hop on a bike and ride."
The ride stays mostly on U.S. 40 and is hilly, but Grey said not as hilly as other rides. He said the entry fee for the ride is $45, which goes to the Bloomington Bicycle Club.
"It's a fundraiser for them," Grey said.
The event is scheduled to begin at 6 a.m. Saturday Riders are given 14 hours to finish the 158 miles.
"Mostly my legs get sore," Grey said.
"I mean, it's in the middle of July. It's hot. But I've been doing this for eight years."
Grey said several bicyclists from the state and surrounding states will be there Saturday to compete.
"People will come all over for this one," he said. "Everybody starts in a big gaggle. They've got some animals that ride this thing."
Grey owns several bicycles for different types of rides. On Saturday, he will ride a short wheel-based recumbent bicycle, which he said was an "up-peddler."
A recumbent bicycle is an elongated bicycle where the back of the rider is supported and the rider's legs extend forward to pedals that are at about the same height as the seat.
"I don't really collect (bicycles), I ride them," Grey said. "(The recumbent bicycle) is my fastest."
Grey said riders generate leverage by sitting while riding a recumbent bicycle.
Grey has already plotted out his plan of attack regarding Saturday's ride.
"You break this down into three stages," he said, referring to the amount of rest stops located on the course. "You ride it that way in your mind.
"I know what I need to do. Barring mechanical failure or a wreck, I have no doubt that I can finish."
Grey is not the only Clay County resident taking part in Saturday's event. He will be joined by Larry Marlow, Jane Neier, Mark Emrick and Bob Lamont.
All riders are expected to complete the course by 9 p.m. Saturday.