SScientists unlock the secrets of bike stability

[krebs303]

In a discovery that could lead to better and safer bicycle design, researchers have shown that long-accepted "gyro" and "caster" effects are not needed to make a bike balance itself. In fact, it's a mixture of complicated physical effects – linked to the distribution of mass – that makes it so a bicycle can remain up when moving.

TMS Bicycle
stable without gyros or trail

(TMS = two-mass-skate)
Long known, but still amazing, is that a moving bicycle can balance itself (see videos). Most people think this balance follows from a gyroscopic effect. That's what Felix Klein (of the Klein bottle), Arnold Sommerfeld (nominated for the Nobel prize 81 times) and Fritz Noether (Emmy's brother) thought [1]. On the other hand a famous paper by David Jones [2] (published twice in Physics Today) claims bicycle stability is also because of something called "trail". Trail is the distance the front wheel trails behind the steer axis. The front wheel of a shopping cart castor trails behind its support bearing and so must a bicycle front wheel, Jones reasoned. Jones insisted that trail was a necessary part of bicycle stability.

 

[brianf7]

It is already banned by UCI
it must have two tri angles

 

[the student]

Hmm i only took a quick look at the website. But how does this make for better bike deseign. It just a simple project about why a bike is so stable. I can make a normal bike roll by itself for longer than they did on the videos.

 

[mastersracer]

They suggest in the original paper (impressive they got this into Science) that bike design has mostly explored only trail and gyroscopic contributions to stability. They show a number of other elements that can make a bike stable or not, and indicate the complex interplay between these elements. They suggest the design space of bicycles has only been partially explored.

 

[goggalor]

"Unrideable" bicycles: http://www.phys.lsu.edu/faculty/gonzalez/Teaching/Phys7221/vol59no9p51_56.pdf

 

[John Hobdeclipe]

"Unrideable" bicycles: http://www.phys.lsu.edu/faculty/gonzalez/Teaching/Phys7221/vol59no9p51_56.pdf

I remember reading a similar article at about the same time...1970-71 or so...in one of the Popular/Illustrated Science Mechanix type magazines. At the time I found it interesting, but years later, after having worked in bicycle shops and done a bit of "racing" and learned a lot more about bicycles, I thought back on the article and asked myself, "Why didn't this guy simply talk to a reputable frame builder to learn why bicycles are stable?"