The only way to stay 20+ on a bike in realistic conditions is with assistance that's likely electric
Your funny! LOL
my "pedal" bike cruises 20mph if I'm not angry (more like 25-30 if I am, but that burns a lot of sugar).
My e-bike cruises 25-26mph (and that is with the smallest motor I could find).
There are a few of us here that can cruise at 25mph+ (giving a door to door average of ~20), but those are racing speeds, and not something anyone is going to do on a daily cruise.