Jobst's theories have to be taken with a grain of salt (or maybe a metric tonne). His book is very useful for building wheels though.
Jerry Moos, who used Jobst's book to build some 650B wheels last weekend Big Spring, TX
Nor Meyer <email@example.com> wrote: I recall reading somewhere (Jobst...?) that the bicycle's geometry is designed to "encourage" the front wheel to return to a "neutral" position---that is, in line with the frame----whenever it's steered away from the neutral/forward position. The reason for this is that anytime the fork is turned from the forward position it imperceptibly raises the front end of the bike, thereby raising the potential energy of the bike & rider. The forward/neutral position for the front wheel/fork therefore represents the most stable position, towards which the bike is naturally inclined---- provided the fork can rotate freely in its bearings. Hence the necessity of properly adjusted headset bearings----needle or ball----for care-free hand's off riding. Which, incidentally, allows the rider a superbly nuanced interaction with his/her machine....
Nor Meyer in Iowa