Simmons was raised in San Jose, California, where his father was a high school educator. He attended San José State University and lived for many years in Santa Cruz County, California. In 1981 he opened a vintage motorcycle shop with author William J. Craddock. Simmons moved to Mendocino County, California in 1990 after the Loma Prieta earthquake of 1989, and later to Hawaii. He met his wife Cristine in 1989 in Sturgis, South Dakota at the Sturgis Motorcycle Rally. They both enjoy riding antique motorcycles, participating in the 2014 Motorcycle Cannonball Endurance Ride. They participated in the 2016 Motorcycle Cannonball, riding from Atlantic City, New Jersey to San Diego, California.