He attended high school in San Diego, California and was involved in motocross racing.
Overend was inducted into the Mountain Bike Hall of Fame in 1990 and into the United States Bicycling Hall of Fame in 2001. Overend moved to Durango, Colorado in the early 1980s where he first became involved in cycling by entering Durango’s Iron Horse Classic – a 47-mile road race with 6,700 feet of climbing along a narrow gauge railroad. From road racing, he eventually moved on to mountain bike racing where, his previous motocross experience combined with his physical fitness from road racing made him an exceptional competitor.
He was first hired to ride for the Schwinn factory racing team from 1984 to 1987 and then signed a contract to ride for Specialized Bicycles.
At the age of 40, Overend made an attempt to qualify for the United States Olympic team to compete in the inaugural Olympic Cross-Country Mountain Biking competition in the 1996 Olympic Games in Atlanta, Georgia. He needed to finish the qualifier race in fourth place to qualify for the Olympic team alongside Tinker Juarez but, one and a half miles from the finish line, he suffered a flat tire and finished in eighth place.
Even though he retired from professional mountain bike competition in 1996, he continued competing in endurance competitions, winning the XTERRA Triathlon in 1998 and 1999 and competing in regular road triathlons. During his professional mountain biking career, Overend earned the nicknames "Deadly Nedly" and "The Lung", because he was very difficult to beat and for his exceptional aerobic endurance at altitude (especially so for a man of his age), respectively.
He is the current captain of the Specialized Cross Country Team.
Overend appeared in "the world"s first mountain biking video, aptly named, The Great Mountain Biking Video released in 1988 by New & Unique Videos of San Diego, California. Overend also appears in competition sequences of "The Sun Valley Mountain Bike Challenge," a video chronicle of that year"s NORBA Championships also released in 1988. He also appeared in a mountain-bike race video entitled "Battle At Durango: The First-Ever World Mountain Biking Championships" videotaped in Durango, Colorado in 1990, and released by New & Unique Videos in 1991.