Anecdotal musing on race

I've had racialization on my mind a good deal lately from some research I'm developing.  Specifically, I've been kicking around questions of how we figure out what qualifies as a racial marker, and what criteria people can use to establish a notion of races among a given group of people.  (By way of example, Americans love to use skin color as a strong index of race.)  I'm especially intrigued by non-somatic racial criteria in non-somatic racial categories.  What can racialization be and how does it operate, when the body only obliquely comes into play?

I bring this up because I had one of those little incidents yesterday evening that got me thinking about academic stuff when I didn't mean to.  I was grabbing a quick dinner at a small restaurant whose personnel are mostly -- maybe all of them, but I couldn't say -- native speakers of Spanish.  They can all speak English well enough, but when they have their druthers, they speak in Spanish to customer and co-worker alike.  (I've been there a lot, so I've noticed the pattern.)  Generally, when someone enters the restaurant, a server will greet them in Spanish and take their order the same way, unless it appears evident to the server that the customer would rather speak English.  As it happened, I was feeling a little uncertain of my Spanish, so when a server greeted me in Spanish, I responded in kind, then intentionally said something to her in English as an experiment.  She kept up with Spanish throughout my time there, even after I slipped in a few English utterances that might trigger a code-switch.

While I sat in my booth, I looked out the front window and saw a customer riding up on a road bicycle that had been fitted with several large panniers -- I can't remember for sure, but he might have had them fitted over both tires, and I know I saw them over the rear tire.  I also noticed that he was wearing hipsterish-looking rainbow-colored high-top sneakers.  (Where did he even find such shoes?)  The thought came to my mind as he parked his bike: That guy is not going to speak Spanish in here.  When he walked in to give his order, the cashier immediately addressed him in English, which was the only language the two of them used in the transaction.

How did I know that would be the case?  What is it about a loaded road bike and funny-looking sneakers that indexed gringo to both me and the cashier?  (And, for the record, I am probably just as gringo as the bicyclist.  I just happen to speak Spanish.)