When I was in high school, I used to road and mtn bike a lot. So we had a similar day. I came in wearing my expensive jersey that I had custom made along with expensive bike shorts, and I got told to put some clothes on... well15 minutes of telling the principle that I wasn't violating anything, they finally gave in. I also told them I would've made it news, at least locally if they didn't lay off.
Heck, for what it was worth, I even carried my helmet around with me all day to promote safety awareness.
After thinking about it that evening, I had to inquire... so the next day I asked to speak with the principle, and asked why it was such a big deal? The principle said, it will make people uncomfortable if you wore spandex bike shorts.
I came back with: Do ya really think I wanted to wear those all day?! Sitting is one thing, but walking around? I told them that it was more of an inconvenience to me, than to anyone else. Then when I told them how much that gear was, they were like, holy $##T. I also asked, what's the different when I throw this same gear on before and after school, than me just keeping it on all day? No one has a problem with it then. Everyone knows and sees me in this crap all the time.
The principle came back with the ubiquitous remark of: "Well, you got a point."
So the following year, I did it again, and no one bothered me...
At the end of the day, it wasn't the that anyone felt uncomfortable, except for the "administration". The principle probably didn't like a male student walking around school in a professional uniform that cost more than his suit and tie...