TMS Bicycle, stable without gyros or trail (TMS=two-mass-skate)

[herpolhode]

Excellent video, great introduction to mechanical physics. Outstanding!

[TheLiberalSoup]

hm, that is a good explanation. I would think at least some of it has to do with inertia of the bicycle and not being able to topple it over as easily, but I dont even know if that makes sense. I dont know, just a thought. If anyone can tell me if this is wrong please respond.

[rvocke]

for those interested (or confused) you can check out the full paper (linked to in the info). It explains everything out quite plainly.

[Grrrrrene]

If you hold an ordinary bike sideways, so as if it would fall, the wheel "falls" in the correct direction. Judging by the drawings in your paper the majority of the mass of the steering part is ahead of the steer axis, so it would behave the same. I wonder what would happen if you had no trail _and_ a steering system that has it's center of gravity exactly aligned with or even behind the steering axis.

[Grrrrrene]

Hmm, shouldn't the counter rotating gyros be on the same axis if they are to truly cancel each other out?

By the way: it is very difficult to get a feeling for this "counter rotating gyro" effect :D

[SquirrelFromGradLife]

the gyroscopic effect of a spinning bicycle wheel is very easily demonstrated and proven by just holding a spinning wheel and then placing yourself in a office chair and tilting the wheel making you rotate in the same direction.

I really do not believe you have dis proven the gyroscopic effect by the counter rotating wheels.. counter rotation works merely in the perpendicular axis not the longitudinal one as far as I am aware. its like the counter rotating propellers on planes or boats.

[SDSMJ]

@SquirrelFromGradLife : the Gyro effect is real and adds to the stability of the bike, but it doesn't correct steering in a fall. To prove this, lock the handle bars into a straight line, or try to push the bike backwards.

[Proemeteues01]

@SquirrelFromGradLife Though I also had to think some time, I found out that the gyroscopic effect is actually eliminated. Why? This effect means basically, that the axis wants to hold it's position in space.

As you mentioned, it can be shown easily by for instance holding a rotating wheel and just trying to tilt it. The wheels will react just like on a bicycle.

Once you turn the wheel into the other direction, the reaction will also be the other way round, and that's why it works. :)

[SquirrelFromGradLife]

@Proemeteues01 I don't understand a word you're saying... not a single one

[Proemeteues01]

@SquirrelFromGradLife Sorry, it is hard to explain, also in order to the limitation of the post's length and maybe my limted english vocabulary knowledge.

I just can ask you to trust me: Both axis try to "escape", but in opposed directions, and that's what eliminates the gyroscopic effect.

[rvocke]

@SquirrelFromGradLife Its not at all like counter rotating propellers in this case. The counter rotation he refers to here is a fairly basic dynamical concept that ties in angular momentum with applied moment (w x L = M). If one were to hold two bicycle wheels is in your example, one spinning in the opposite direction of the other, there would be no net moment induced in the chair.

[Boo8054]

Fantastic work!

"We did that" :-)

[gregcdowns]

nice one

[DrJonezzz]

This discovery is truly amazing!