Depends. A respectable average speed, and a respectable maximun speed are indubitably, two different things.

What roadies are doing depends on: Terrain (flatter terrain would generally = a little higher avg speed compared to a hilly/rolling terrain), distance of ride, type or rider, strength and fitness of the roadie, whether one rides w/ a fit/fast group or solo, purpose of riding (experienced racers out training will typically be moving swiftly; non-racers but fit riders might have a little slower avg speed; fitness/recreational riders might be a lttle less, still).