Accelerating a pedal-powered bike by 135kph / 83mph is a stunning accomplishment. I am flabbergasted that you don't see that as something notable.
I just don't know either way. I would imagine it comes down to how much time or distance she had to accomplish that acceleration.
Because without significant wind resistance, and with appropriate gearing ratios on the bike, honestly I just don't know what else would be physically demanding.
From https://www.wired.com/story/denise-mueller-korenek-bike-spee... - 700W over a minute is very physically demanding.
Wouldn't balance actually be easier, due to the gyroscopic effect of how fast the wheels would be turning?
https://ezramagazine.cornell.edu/SUMMER11/ResearchSpotlight....
The article you link only claims that the gyroscopic effect is not everything stabilizing a bike.