It appears special clothes made especially for cycling is not a recent trend.
This advertisement for “Thomas E. Kent for Bicycle Clothing – 597 Mission Street, San Francisco” appears in the margin of Blum’s Map of California Roads for Cyclists published in 1896.
Yesteryear’s athletic apparel to wear while sweating on La Honda Road is today’s practical but fashionable cycling garb for the dandy and his casual city riding. This is Greg in San Francisco wearing custom hand crafted EXiT shoes and B. Spoke Tailor knickers and vest.
The map was published along with George Blum’s “The Cyclers’ Guide: Road Book–California.” The 80 page book included seven sectional relief maps showing all available cycling roads from Chico to San Diego plus a map of Golden Gate Park.
The poster of the big map, incidentally, is available through Zazzle from Big Map Blog. It would make a decent gift for your cycling friends.