In 1995, a University of Rochester press release announced the invention of a six-speed "smart" bike that used a programmable chip to automatically shift gears. Basically, the chip measured wheel speed and pedal motion, then used a mathematical algorithm to determine whether the bike's chain was under tension (an important factor in shifting).
At the start of the ride, the cyclist would press a few buttons to program the chip, thereby establishing how fast the cyclist wanted to pedal. Then, if the cyclist tired during the ride and began to pedal slower, the chip automatically shifted to a lower, easier gear (and vice versa if the cyclist pedaled faster, such as when going down a hill).
The additional cost for this feature was to be only $200...so what has happened to this "smart" bike? Does it exist commercially? And even more importantly, what does the mathematical algorithm for shifting look like?