To the mtb pioneers in America, the plaid shirt appears to be required dress. I challenge you to find a 70's picture from the USA that doesn't feature one. I love it though, because it's sums up the whole spirit of the guys that effectively created mountain biking as we know it. The nod towards safety shown by the slightly thick cotton and long sleeves is pretty pointless, but hey- you might crash, just don' t get hung up on it. It's this devil-may-care attitude that stopped fear getting in the way of what was probably a pretty barking thing to do.