system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] Could the Flash beat Usain Bolt at the olympics?

Sounds stupid, I know, but hear me out.

Does the Flash have complete control of his speed? So if no one knew who he was, could he show up at a race and run at normal person speed, except faster than every other normal person in the world? Then everyone would just be like "wow that guy runs fast" and move on?

Or are his only two modes average person speed (in which case he loses) and superhero speed (in which case he wins, but everyone says "well yeah, he's a superhero")?
gpt
So he has to outrun Usain Bolt WITHOUT tipping off the world that he's the Flash. He has to pass as merely a very fast human. 

1) Yes, in general a Flash moves as fast as they can think about moving, if they maintain focus. However: 

2) all the Flashes are ordinary CSIs who, to the best knowledge of everyone in their lives, do not undergo the kind of lifelong training Olympic sprinters do. Someone is surely going to think it's rather odd that an untrained lab jockey from Flash's home city is casually outrunning Olympic champions.