Originally Posted by
Salamandrine
...I'll stick by my initial explanation that cost was the original driving factor. Shimano and others started experimenting with painted components in the late 80s (roughly) primarily to save polishing costs. They were typically gray though, not black...
My recollection is the very late 1980s move to painted components started upscale and trickled down. Shimano Santé broke the ice with its mini-group in 1987. Nestled in between 600 and Dura-Ace, pearl white with grey was chosen for the finish. It was designed for the yuppie market and aesthetics was the high priority. The colour combination was considered the most favourable match for the intended market and the Miami Vice influenced, pastel, frame colours that were popular at the time. Cost was a secondary benefit. The painted finish was trickled down to 600 Ultegra and other lower groups for the 1988 model year, in various shades of silver, grey and black.