General classification - (GC) -- the overall standings in a stage race.

Glucose - a sugar, the final energy-producing fuel of the cells.

Glycogen - a sequence of glucose molecules that forms the principal carbohydrate storage material in the body.

Gnarl - extreme technical sections. Characterized by very rough, rooty, slippery, or rocky sections. "He has got some great bike handling skills and can really scream through the gnarl."

God - He made us, He made the Mountains, He made the bikes. Gotta love Him. He is the Greatest!! 

Gonzo - treacherous, extreme. "That vertical drop was sheer gonzo."

Gorp - good ol' raisins and peanuts, a high-energy mix to nibble on during rides. Can also include nuts, seeds, M?, granola, etc.

Granny -God made my granny, too. She's 90, but in off-road terms, we're not referring to the fabulous and beautiful Betty Brenner, of Coney Island, Brooklyn. Instead, we're talking about tiny gears that get us up big hills. Another miracle.

Granny gear - smallest chainring combined with largest cog, used mainly for climbing.

Grinder - a long uphill climb.

Grindies -  e.g., "All that dried mud and sand left me with a loud case of the grindies in my drivetrain."

Grip Shift -The gearing alternative to Shimano - still the major player in that very tough game - and trying hard to grow with it's acquisition of Sachs. The problem is that Shimano's stuff is just so danged good.

Gutter Bunny - a bicycling commuter.