Comment by tylervigen | Hacker News Reader

Comment by tylervigen | Hacker News Reader

I learned a fun fact this year that completely changed how I think about wheels.

Ancient wheels supported weight through compression: the cart pressed down, the wheel transferred that force straight into the ground. Simple and solid.

Modern wheels? Totally different. Bicycle wheels hold weight through tension. If a bike is standing still, you could cut the bottom spokes and it would stay upright. Cut the top ones and it collapses—the rim is literally hanging from the hub.

Even car tires follow this principle. It’s not just a balloon of air under the wheel. The internal pressure forms a tensioned ring that holds the car up. The car is suspended from the tire, not resting on it.

So while the article encourages reinventing the wheel metaphorically, I can’t help but admire how we’ve already reinvented the wheel literally—by flipping the physics entirely.

If you're visual like me, this video illustrates it perfectly: https://youtu.be/8I7QsgYm_NU?si=Vz1aqpHBAPjayqlG

Yes, as TFA alludes to, this expression is actually a bit wrong because the wheel has often been reinvented since ~4500 BCE. The latest "reinventions" are as recent as 19-20th century with the continuous track, monowheel, "hubless" wheel and mecanum wheel [1] [2].

[1] https://en.wikipedia.org/wiki/Hubless_wheel

[2] https://en.wikipedia.org/wiki/Mecanum_wheel

It seems to me that most people say, "don't reinvent..." because they believe there is an existing, ubiquitous, sufficient solution (well, that's why they think it. Why they say it out loud as a response to someone's project, I have different theories on that).

But in ubiquitous solutions, we also find assumptions and trade-offs that require constraining the application to fit the solution. Thus it is there, in those assumptions and trade-offs, as these literal wheel examples demonstrate, where we find the ability to usefully reinvent.

I have to laugh a little seeing your reference to Mecanum wheels and your post being dated 6 hours ago. 12 hours ago, I rewatched the Star Trek reboot film. In it, there is a scene where the characters are all loading into shuttles to head off to their assignments. In the background, we are supposed to be impressed with the technical advancement of the machinery in view, e.g. how something as familiar as a forklift has "futuristic" details like strange wheels. And those wheels on that forklift are Mecanum wheels. In-story, that makes them something like ~300 year old technology.

That was very interesting. I had never thought about this earlier. I learned something new today! Thanks.

This is exactly why I read hacker news. Thanks for sharing.

circular tensegrity

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