4 Wheel Bob tells the story of wheelchair hiker Bob Coomber and his attempt to be the first wheelchair hiker to cross the Sierra Nevada. Bob has hiked more than 100 parks in the Bay Area, and was inducted into the California Outdoors Hall of Fame in 2007. Over the past decade, state and national parks have tried to cope with budget cuts, sequestration, and a dwindling number of visitors. As a board member of the East Bay Park district, Bob aims to motivate, educate, and inspire the public to discover California’s great outdoors.

The film addresses two important themes: the ability to overcome adversity, and environmental conservation. There is a large population of the disabled who are wheelchair-bound yet able to get outside and experience nature. The challenge is to overcome internal struggles and fears. Experiencing nature and the outdoors can be quite therapeutic for the disabled, who often suffer from depression. Bob suffers from debilitating osteoporosis, and after a severe period of depression, it was Bob’s determination and his motto of "no excuses" that led to an obsession with wheelchair hiking as a way to gain his health back.

The kind of hiking Bob does is fraught with danger. With very limited use of his legs, he must turn backward on steep hills so he can push with his arms while his feet are on the ground stabilizing his wheel chair. Going downhill can be even more hazardous. Bob improvises switchback turns, his wheels often skidding on loose rocks and dirt. "I've fallen over plenty of times, but I haven't gotten hurt," he said. "I just pull myself up and get back in."

In July 2010, Bob was given the President's Council on Physical Fitness and Sports Community Leadership Award. Bob motivates other disabled, leading groups of military veterans on nature walks and leading children on adventures in his role as a volunteer ranger and member of the East Bay Park District. Coomber hopes his example will inspire wheelchair-bound children, war veterans, and shut-ins with disabilities to push themselves into the vast, beautiful world that awaits them. "I always hope that people will see me and decide that they are doing too little with their lives. It would be nice if more people would test their limits... and it would be nice to share this with people. It's an awful lot of fun."