Sprinters and these cyclist guys have big legs only because they incorporate weight training into their regimenes. When steroids are added then its no surprise.
Has anyone seen sprinters/cyclists of the 50s, 60s, 70s, etc? They all look like a normal average person with no muscle.
What changed? Weights were added and of course steroids.
Plus these guys are the elite at what they do, ever seen the normal high school/college athlete? far from these guys.