In the fall of 1975, Wally Dallenbach and Sherm Cooper invited seven friends including Al Unser, Sr. and Bobby Unser to ride various mountain trails and visit mining ghost towns in the Colorado Mountains. Wally Dallenbach was an Indy car driver while Sherm Cooper was an amateur motorcycle racer during the 1950s. Participating on the first trail ride were Dick Singer, Lon Bromley, Art Lamey, Del Garner, Ed Kretz and the Unsers. Having enjoyed the ride and the camaraderie, Dallenbach and Cooper continued to organize the invitation-only events.

The guest list quickly expanded and in 1977 about 30 people participated including Roger Penske and Rick Mears. Penske’s open-car team had won the 1972 Indianapolis 500 and was already on its way to becoming a dominate force in open-wheel racing. Rick Mears had just broken through to the ranks of open-wheel racers after being named the United States Auto Club championship-circuit rookie of the year in 1976. While Mears had passed the Indianapolis 500 rookie test in 1977, he did not make the field of 33.

The participants rode about 400 miles over four days. Rick Mears told the Indianapolis Star of the meeting which changed the trajectory of his career. “One morning I came out of the motel and began to clean up my motorcycle. Roger Penske’s motorcycle was parked next to mine and he asked me if I had anything going. I said I might talk to the Shadow car people, who were thinking about entering the 500, and he said he had something in mind and to let him know what I was going to do.”

After the Michigan race, the two men talked which resulted in Penske signing Mears to a one-year contract to join Mario Andretti and Tom Sneva on a part time basis in 1978. At the time, Andretti was also participating in Formula 1. The contract was for nine of the eighteen USAC races plus the Indianapolis 500. Mears, who was the first rookie to qualify at over 200 mph, joined teammate Sneva, who started from the pole, on the front row. Andretti, who was racing in Europe during the first week of qualifying started from the 33^rd spot. Despite having two racers on the front row, the Indy 500 was a disappointment for Team Penske. While Sneva finished second, he was more than eight seconds behind winner Al Unser, Sr. Mears’ engine failed on the 104^th lap. Andretti finished 12^th after a coil went bad necessitating a pit stop.

During his first year with Team Penske, Mears showed his skill with wins at Milwaukee, Atlanta and Brands Hatch in England. Despite driving part time, Mears finished ninth in the championship points. Mears’ contract had an option for a second year which Penske elected. In 1979, Mears won three races including the Indianapolis 500 as well as the championship. Mears became the only Penske driver to win four Indianapolis 500s. He also won three CART championships.

The dirt bike ride through the mountains continues and is now known as the Colorado 500. In 1981, Cooper and Dallenbach established the Colorado 500 Charity Fund. The fund has raised more than $1.2 million for scholarships, medical centers, teen services, scouting and the U.S. Forest Service.