Digital technology is on the brink of radically redefining a technology that has existed with only minor changes for more than a hundred years: Shimano Shuns Cables for Full Electronic Shifting.

Japanese parts manufacturer Shimano is launching an electronic shifting system for high-end road bikes that it claims will vastly improve performance and reduce maintenance. By replacing the conventional levers that pull wound-steel cables through protective housings with solid-state switches and rubber-coated wires, there’s no chance for road gunk to clog things up and interfere with shifting, or, for that matter, your post-ride beer.

The principle of an electronically controlled drive train is to execute perfect shifts every time, thus “reducing mental overhead,” in the words of Shimano marketing manager Devin Walton. This is a resource cyclists find in short supply during epic rides.

Thursday’s announcement that the system, called Di2, will hit shops in January 2009 settles a question first raised in 2005 when prototypes began cropping up on the bikes of select Shimano-sponsored racers in the pro peloton. The system’s development has been photographed, chronicled and Angsted over ever since.

But if the existence of electronic shifting comes as no surprise, its weigh-in certainly should. During a recent telephone interview, an industry insider who spoke on condition of anonymity stopped cold amid a why-do-we-need-this diatribe, upon learning that Di2 weighs less than Shimano’s current generation of parts. According to the company, Di2 will be 67 grams lighter than the current Dura-Ace 7800 and only 68 grams heavier than Dura-Ace 7900, the snazzy forthcoming 2009 suite of parts. “I’ll be going to hell,” said the source, who then fell silent — no doubt converting grams to ounces to fractions of a pound to the limitless advantages of such weight savings. That’s at least an extra Clif Bar.

The amazing thing about this story is how long the cable/pulley derailleur system has survived. It’s a really elegant analog solution. I can’t help thinking something will be lost in the digital translation…