Secondly, the hand and eye coordination involved in Biden riding a bike does not prove mental fitness on his part, as people have talked about loved ones possessing the hand and eye coordination to drive a car, make turns, stop, accelerate while turning, parking, etc, only to discover their loved ones couldn’t remember where they lived or even their way home.
One of my mom’s best friends got dementia so severe she became mute, but could still play the organ beautifully for a while after that.
My mom with 11 years of Alzheimer’s behind her can play the piano and if seated can even play ping pong. Doesn’t mean she has any frontal lobe or executive brain functioning.