"G" Slang

Older slang for a US Marine, in circulation since at least the early 20th century. Most accepted etymology blends 'GI' and 'Marine' into one word. Used affectionately by Marines and by old salts in the Navy; younger Marines today are more likely to use 'Devil Dog' or 'jarhead', but you'll still hear gyrene from senior NCOs and Vietnam-era vets.

Also called a detangler, a device fitted to the head tube that lets the handlebars spin a full rotation without twisting or snagging the rear brake cable. It makes barspins possible on a braked bike.