My mind is blown, someone please explain this!

[Bruce]

they are harder to make than spheres, so expensive.

Maya will find you and convince you that spheres and wheels in general weren't easy at all :)

 

[Vavrik]

Maya will find you and convince you that spheres and wheels in general weren't easy at all :slight_smile:

lol. they weren't. If it took us until around 3500 BC to figure out how to make things go around and around (first known wheels were for pottery), and another about 300 years to figure out how things going around could make things go in a straight line (chariots) without rattling itself apart. So we've had wheels for around 5200 years, out of around 200,000.

 

[Talonsbane]

Here is some video of main in China who thought it is the same :slight_smile:))

View: https://youtu.be/ebRI4kFmR7U?t=9

This looks like a great design for a strength & endurance training bike.

If you likes those shapes you may like this one: The Gomboc.

it's a shape with just one point of equilibrium. No matter what side you put it down on, it will always, always return to its rest point, with no added weights or tricks.

If the video went on long enough it would stop rocking, and it would always come back to that point even if it were turned upside down, placed on its side, on its end etc.

I had an intelligent reply to this post, but @Vavrik beat me to it with great finesse.

The trick to the gomboc is, any rotation from the point of stability causes the center of mass to become offset from the center of rotation. there are tons of shapes indeed, but at least there is a commercial application. They're not just curiosities. The hull of a self-righting displacement boat or ship, is usually in the form of a gomboc.



Well, roleaux polygons (these aren't called Obiform) work because if you roll them, the side exactly opposite the point of contact is always the same distance from the point of contact. Make two 2d identical roleaux polygons out of cardboard, and place them between two rulers. You can see this at work a little better and play with orientations to see if it makes any difference.

It doesn't really have anything to do with the center of mass, it's the dimensional change as you go around the polygon.

By the way, you can have roleaux polygons made with any odd number of sides over 1, so 3, 5, 7 9 etc.

I couldn't have possibly stated this as well as you did. Great job. Cheers!