[math-fun] Thm: You can never fully complete a lane change, even on a bicycle.

https://en.wikipedia.org/wiki/Tractrix http://mathworld.wolfram.com/Tractrix.html http://mathworld.wolfram.com/PursuitCurve.html Unfortunately, https://www.its.caltech.edu/~mamikon/calculus.html appears to be broken. At any rate, to get your rear wheel traveling exactly straight in a new direction, you need to undercorrect your steering until the rear wheel is on the target line, and then continuously adjust the steering to keep it there. Of course, these adjustments will rapidly "incede" atomic diameters. —rwg