Where I am, middle class people and up wear specialized clothes for sports. Riding a bicycle can be cheap, but the specialized clothes often are not: more than that they aren't necessary. Unnecessary expenses are for people with extra money. In the summer, you can wear a pair of shorts and a tee shirt you spent less than a dollar on from a thrift shop and be fine riding a bike. Cold weather sporting gear can be even more expensive.
Here, a lot of fast food places and restaurants require employees to wear black shoes (usually tennis shoes) and black pants (usually black jeans or chinos). Someone wearing black shoes and black pants riding a bicycle has a better than fifty percent chance of working at a fast food place or restaurant and is riding a bike because they can't afford a car, can't afford to fix their car, or their partner/family member with whom they share a car is unable to give them a ride/let them use the car. I've known one or two people to do it because they are afraid of getting fat, but they generally didn't turn down rides when they were offered, especially in bad weather. And they didn't have specialized clothes.
It's not 100% accurate and it depends how much you are into fitness. I have no idea how things are in other areas, but I've lived in this town for over thirty years. I've watched it decline and, though I'm not very social, my family has been here or in the neighboring counties for generations. I mean, back to one that came over on a boat, served in the Revolutionary war, then managed to settle in Indiana before dying.
So I know the area and I have a pretty good feel for the people. A lot of the people I know are poor and working class. I know some people that are better off, too. Like my cousin recently was trying to sell over seventy pairs of her daughter's sports shorts on facebook. They are cheap shorts, but they are specialized: they do not meet the dress code for our public schools and over 70 pairs. One kid. I would think it was a typo, but I used to clean her sister's house and that's really not out of line for them.
I know it hurts people's sensibilities to be categorized based on very surface things. I don't always like it myself, but even with me, it's generally pretty accurate. I dress and look maybe a little younger than I am, but no one is terribly shocked after seeing me to learn that I am a housewife and mother or that my husband is a truck driver. No one would be shocked to learn I'm from a conservative religious background. I drive a mini-van. I wear Danskos, jeans, Lands' End tops. You could guess a lot about me by the way I look.
My political ideas would probably come as a surprise unless you happened to catch me driving our second car: a compact car with a marriage equality bumper sticker. But usually the only thing people express surprise upon learning about me is my age and the ages of my kids. The fact that I still have all my visible teeth says a lot about my economic situation in this area, as does the fact that they are not perfectly straight or bright white.
Now my husband, my husband does not look like a college educated fiscal liberal. He does look like a truck driver and no one would be surprised he is from a conservative religious background to look at him unless he was just off work and had had to crawl around on the ground for some reason, which happens sometimes.
But anyway, my point is that most people do make judgements about us based on how we look and to some degree, those judgements are accurate. I'm sure there are some people who do not make those judgements, but I suspect that even when we think we don't we just aren't doing it consciously. I'm fairly conscious of it because I've been followed around stores like a thief based on how I looked, even though the last time I shop-lifted I was four years old. I've been told by a dentist that he didn't give a shit about me and that I was nothing when I complained about how he was treating my daughter because we were on Medicaid (obviously poor).
Learning that people are like that was not a pleasant revelation to me, but it was pretty undeniable. I've done what I could to mitigate the negative effects of that kind of thing since I figured it out. Being aware of it gives you a little control over it but no one can completely overcome it. If Oprah can't buy a pricey bag without being talked down to, I hardly think the rest of us are exempt.
But I am not going to argue it further. Life is too damn short and there are much funner things to do. And virtually anything else I chose to do with my time would be more useful.