> They built a bicycle with two small wheels, each matched with a counter-rotating disk to eliminate the gyro effects

...to double gyro effects... or I missed something?

Two conter-rotating disks will compensate each other, BUT they must be perfectly aligned, is not?

In their bicycle, upper disk produces about 2x of gyro effect comparing to lower disk gyro effect, because it moves with about 2x larger amplitude comparing to lower disk at same incline, thus we still have about 2x-1x=1x gyro effect.

They should try their system on skates with two tiny blades instead of wheels.

PS.

Sorry for my English - I am Ukrainian.

PPS. System need to spent some energy to restore vertical alignment of inclined body.

Thus they need to add small incline to bicycle and then find where motion energy is spent by bicycle to restore vertical alignment. If bicycle will unable to restore vertical alignment then it is not stable.