On Fri, 4 Jan 2019 10:43:12 -0800 (PST), Sir Ridesalot
wrote:

On Friday, January 4, 2019 at 12:28:54 PM UTC-5, Frank Krygowski wrote:
On 1/4/2019 11:37 AM, wrote:
https://www.nature.com/news/the-bicy...matics-1.20281

Of course this isn't for John or Frank who could fall down if they were sitting on the ground.

You're just reading that now??

--
- Frank Krygowski

Seems to me that the guy has made a few basic false assumptions.
Any bicycle I've ever seen with the front fork in it's proper position
soon falls over after being pushed without a rider on it. I also think
that the gyroscopic force of rotating bicycle wheels keeping the
bicycle upright is miniscule unless the wheels are turning at very
high revolutions. I once saw a video on You Tube of a normal bike
with the front fork reversed, and without a rider, that went quite a
distance when pushed before toppling over.

I think too that making a bicycle stable enough to be riderless might end up being extremely difficult to ride. Look at how even small changes in frame/trail geometry on a road bike creates quite different handling characteristics.

Cheers

There has been a lot of research into what makes a bike stable. One
paper I read described a bike that was built with a front fork that
allowed the trail to be adjusted from a negative number to a rather
large positive number and yes "trail" has a great effect on the (would
one say) the longitudinal stability of a bike - how easily the fork
turns, and during the same experiment it was "discovered" that BB
height, vertical location of center of gravity, also effected this
same stability. Bikes have also been built with counter rotating
wheels which counter act the gyroscopic effect of the spinning wheels.

My own guess is that bicycles require stability in at least two planes
and so far no one seems to have built a bicycle that is completely
stable.

cheers,

John B.