Originally Posted by Bandera

Having been involved with riding fixed gear bicycles on the road since the Johnson administration, and having spent a fair good bit of time at/on the track since the early '70's I never heard a fixed-gear bicycle referred to by my coaches or teammates as a "Fixie" for the last few decades. Perhaps I missed it.

I believe that the term has entered the language recently, along with a generalized infantile diminution of nouns.

A generalized etymology source on "Fixie" has:

"fix·ie
ˈfiksē/
noun
noun: fixie; plural noun: fixies

A single-gear bicycle that has no freewheel, so that its wheels cannot move unless power is applied to the pedals.

Origin
early 21st century: from fixed-wheel bicycle or fixed-gear bicycle ."

Perhaps we moved in different circles (pun unintended) but it's interesting how the language evolves, with some unfortunate turns of usage at times.

-Bandera