Maybe he got to caught out by the word "bicycle". Tony Foale has built motorcycle frames with no rake, various amounts of trail, etc. and written a book about it. http://www.tonyfoale.com/ Vittore Crossalter has done a lot of computer simulation and studies of motorcycle stability and also written a book https://www.amazon.com/Motorcycle-Dynamics-Second-Vittore-Cossalter/dp/14303... Brent On 7/20/2016 6:54 PM, Michael Kleber wrote:

Nice Nature article on the study of bicycle dynamics:

http://www.nature.com/news/the-bicycle-problem-that-nearly-broke-mathematics...

Excerpt:

""" He first rewrote the bicycle equations in terms of the caster trail, the crucial variable that Jones had championed. He expected to find that if the trail was negative, the bicycle would be unstable, but his calculations suggested otherwise. In a report that he prepared at the time, he sketched a bizarre bicycle with a weight jutting out in front of the handlebars. “A sufficiently forward [centre of mass] can compensate for a slightly negative trail,” he wrote. No single variable, it seemed, could account for self-stability.

This discovery meant that there was no simple rule-of-thumb that could guarantee that a bike is easy to ride. Trail could be useful. Gyroscopic effects could be useful. Centre of mass could be useful. For Papadopoulos, this was revelatory. The earliest frame builders had simply stumbled on a design that felt OK, and had been riding around in circles in that nook of the bicycle universe. There were untested geometries out there that could transform bike design. """

--Michael