Here is a basic explanation of Crank Length. A more in depth analysis is here: https://www.youtube.com/watch?v=ydePgGR1Lu8&t=732s.
ps. sorry I muddled up rpm and pedal velocity at one point. doh!
1:04 crank length vs power
5:02 crank length vs acceleration
5:30 crank length vs gear ratio
7:30 crank length vs fit
10:00 crank length vs cadence
The Basics Of Crank Length (Effect On Power, Cadence, Comfort)