TMS Bicycle, stable without gyros or trail (TMS=two-mass-skate)
Why Hacker News recommends it
HN commenters cite it as the author's own demonstration of research showing that bicycle stability is not explained by gyroscopes.
What it is
Arend Schwab demonstrates a research bicycle, the two-mass-skate design, that balances itself without gyroscopic effects or trail. It challenges the common explanations for why a moving bicycle stays upright.
Recommended by 2 HN commenters across 1 different months, 2013 to 2019.
What Hacker News said
Recommends schoper · 2013-08 · on “We still don't really know how bicycles work”
We do know, here is the paper that the journalist refers to: [LINK] And here is a great video by the author: [this video] Short answer: "a bicycle should turn into a fall."
Recommends aray · 2013-08 · on “We still don't really know how bicycles work”
[1] Explanation of the research in question behind this article, as well as a demonstration of the bike they based the research on. They very clearly describe (at the end of the video) that even with gyroscopic and tracking forces removed, the two most important factors are where the center of gravity is, and the tendency to turn into a fall (arguably just the second, but it is caused by the location of the center of gravity with regards to the pivot). [1] [this video] Edit: more info on the TMS (two-mass skate) bike at its wikipedia page: [LINK]
Cites jessaustin · 2015-09 · on “How Far Can a Motorcycle Lean in a Turn?”
I don't think either of us understands that experiment. Fortunately, actual engineers have proven that bicycles don't stay upright from gyroscopic effects. [0] [1] If you want to experiment, try riding a bike that can't be turned. You might want to wear a helmet for that one. [0] [LINK] [1] [this video]
Cites nitwit005 · 2019-07 · on “Why did we wait so long for the bicycle?”
There was still active research into why bicycles are stable as recently as 2011. Here's a talk about that research: [this video] If the bicycle was some sort of "obvious" machine, people wouldn't still be studying the basic stability mechanics 200 years later. Very few things are as simple as they seem. Even levers can get a bit complicated.