Originally Posted by
Schweinhund
A bike has two gyroscopes. the lighter those gyrocopes, the quicker they spin up. the more mass, the greater gyro effect.
So a 16/20" bike like a folding bike has a greater stability at a slower actual speed.
A cruiser doesn't have that going for it, so you're pretty much limited to larger lighter wheels and a smaller front chainring or very small wheels and normal gearing to increase the reciprocating gyroscopic effect. (cranks/wheels turning)
ITYF that gyroscopic effect has been shown to have minimal influence on the stability of a bike, such that you might notice it when riding no-hands, but not otherwise, certainly not when starting from stationary. Motorcycle wheels do exhibit gyroscopic behaviour, but they are more massive and spinning faster.