Mark Reynolds, 48, crashed into a dirt embankment on a relatively flat portion of the downhill course during the Sea Otter Classic on Saturday at the Laguna Seca Recreation Area. He was taken by helicopter to Natividad Medical Center in Salinas, where he died.
An autopsy conducted Monday revealed that Mr. Reynolds suffered fatal injuries in the accident, deputy coroner Thomas Jenkins said. Initial reports that Mr. Reynolds, an amateur racer, may have suffered a medical problem before he crashed were incorrect.
The accident happened near the finish line of the downhill course which, according to race organizers, contains "a great mix of jumps, turns, pedaling sections and hi-rev speed traps" and "rewards racers who demonstrate fitness, precision handling, braking and pedaling skills."
In the downhill race, cyclists compete one at a time against the clock, and the course usually takes 2 1/2 to 3 minutes to negotiate.
Mr. Reynolds was racing in the amateur category for 40- to 49-year-old men and had competed in past years, said Frank Yohannan, president of the Sea Otter Classic.
"We're deeply saddened," Yohannan said. "Mark was an avid cyclist who loved the sport and who was a mentor to a lot of kids. He was a wonderful representative of the sport of cycling."
According to Yohannan, hundreds of competitors raced on the course without incident, and the downhill route had been inspected and certified as safe. Mr. Reynolds, like all competitors, was wearing a helmet.
Mr. Reynolds, a software developer, was the inventor of the Dualrailleur Guide, a $125 plastic device that attaches to the front derailleur of a mountain bike and ensures smooth gear shifting under race conditions. He sold the device at biking events and by mail order from his home.
He was a native of Redwood City and a frequent cyclist in the Santa Cruz area. Fellow riders called him inspirational, devoted and helpful.
"He would make you feel like you could do anything on a bike," said his friend Kris Vantornhout. "He was such a gentle and beautiful soul."
Mr. Reynolds was also a snowboarder, a golfer and an airplane pilot. His death is believed to be the first in the 18-year history of the Sea Otter Classic, which this year drew 45,000 fans to the four-day competition.
He is survived by his wife of 13 years, Margo Maida, of San Jose, and by a daughter, Kristin Reynolds, of Sunnyvale.
Plans for a memorial service are pending.
E-mail Steve Rubenstein at srubenstein@sfchronicle.com.