Sinclair (54), a rescue foreman at Dunedin International Airport, finished 19th in the race in 25hr 59min 50sec.
There were 112 starters for the gruelling event in the United States and 64 finished.
Sinclair was second home in the over-50 age group.
Sinclair is an experienced ultra-distance runner and has contested 20 events in New Zealand.
His only previous international experience was in the Great Western race in 2005.
He did a few five-hour runs but did not overdo the training.
"I do shift work and run most days," Sinclair said.
"I would rather be underdone at the start than feel like toast at the finish."
The Tahoe event is a mountain race that reaches an altitude of 2750m on the Sierra Nevada mountains.
"I consciously tried to go slow on the first lap and walked up the steep hills."
Sinclair's goal was to break the 26-hour barrier.
He was on target after finishing the first of the two laps in 11hr 40min.
The race started at 5am and during the day temperatures reached 40degC.
The surface was granite and black sand, making for easy if messy running.
"My legs were covered in black dust. It was like talcum powder," he said.
There were seven aid stations on the course and Sinclair's wife, Aileen, was stationed at Tunnel Creek.
"The hardest part for me was trying to speed up at the end to break the 26-hour barrier," Sinclair said.
A pacer is allowed in the event and an American friend ran with him for the last 25 miles.
"I was starting to hit the wall and had slowed to a walk," Sinclair said.
"He helped me keep running."
There was plenty of food and drink at the feeding stations and Sinclair made a point of filling his two water bottles to make it easier for him to get to the next stop.
The runners were given hot noodle and vegetable soup that was cooled with ice cubes to make it easier to digest quickly.
He also drank flat lemonade and ate fruit.
Sinclair has not attempted any drastic exercise since returning to Dunedin at the weekend.
His next challenge is the Great Naseby Water Race on August 29 that has options to compete over 50km, 80km or 100km.
There is also a two-man team event over 60km.
