Nawab had constructed a gear mechanism so that the antenna on the roof could be turned from inside the house to improve reception.

NEWYORKER: Nawabdin Electrician

Derailleur gears have a front mech (short for front gear mechanism) to shift the chain between two or three chainrings and a rear mech (short for rear gear mechanism) with up to 10 sprockets.

BBC: Sport

In July Toyota unveiled a concept bicycle, the PXP, with a thought-controlled gear-shift mechanism.

ECONOMIST: Brainwave controllers