I believe all the gyroscopic stability theory of the wheel spinning to keep a bike stable was completely debunked in the 80s by demostractions that bikes with contra rotating and 90 decree off set were all perfectly rideable.
I believe modern thinking is that rear wheel castering and the general rpm of the wheels yields the stability to be able to cycle.

Meanwhile, a folding bike going faster than the speed of light would require an infinite amount of energy to slow it down. Einstein tachioned this to the general theory of not getting on with his relatives. I might have not been listening to this physics lesson properly. Anyone seen my cat, hope he's ok.