Hahahaha!
Quite interesting & funny! I liked it!


We also use the equivalent word for "Granny" (Vovozinha) to refer the smallest chainring.
It doesn't fit to the spirit of "Só no Girinho", but it's quite cute..."Granny Gear"...

About the cognate sound, it's because you say "Girinho" with your phonetic alphabet.

In portuguese, it has a different sound...the "G" sound more like "J", the "R" is completely different than the "R" on the word "ARM" and the "NHO" sounds like the spanish "Ñ" like in "señor".

Try listen on Google Translator "Só no jiriho" in english and then try "Só no Girinho" in portuguese. You'll see that is very different.

Idioms & Phonetics are the most difficult part of learn a foreing language...but is also the most exciting part!