So yeh, bring along yer worst, garish, retro garb & I'll dress up in it for a laff & pics (& obvious general abuse..
I don't know how to beak it to you guys, but I get up and go to work every day in absolutely authentic "retro" mountain biking clothes, the same shit I have worn every day of my life since the Army let me out and I could make that decision. It's pretty much the same shit Gary Fisher wore and Joe Breeze wore back in the day. Blue jeans, tough shoes and a tough shirt. If you wore a cloth cap, you turned it backward. There you have it, retro fashion.
Joe had a thing for blue work shirts (neatly tucked in) and a bicycle cap, Gary favored some sort of rugged long-sleeve buttoned shirt untucked and bell-bottom jeans which always had the right cuff shredded and blackened from his chain. He usually wore a wool cap. Everyone wore blue jeans unless they wanted the "best dressed" award, which went one year to a guy who raced in a tux and another to a guy who raced in a costume that can't be described easily.
I raced in genuine Levis 501 jeans and generally my old Army fatigue shirt at first, switching later to long-sleeve BMX jerseys and knee and elbow pads. I wore knee pads from the beginning, because I was skateboarding too and I had them so I used them, adding elbow pads later. I never wore a helmet, but one guy had a hockey helmet. Hard-shell bike helmets were not generally available, and even though I had a skateboard helmet,I didn't wear it.
These days I usually ride in something more comfortable than jeans, and I wear a jersey and a helmet and (obviously) cycling shoes. There's a good reason all that stuff got invented. It works better than "retro" clothing.
BTW: The last necktie I owned was part of my Army uniform. I got out in 1968 and haven't worn once since. There is nothing I care to do which involves wearing a necktie.
My book, Fat Tire Flyer: Repack and the Birth of Mountain Biking
is at your bookseller and on Amazon