a direct-drive setup using one chainring and one rear cog, as on a track bike. When the rear wheel turns so does the chain and crank; coasting isn't possible.

There is no coasting on a fixed gear bicycle. You must pedal continuously and you slow down by reversing your “thrust”, by adding resistance to the pedals with your legs to stop them from going around. This makes stopping quickly more difficult. Only the most serious of cyclists ride fixed gears.

Landing gear that cannot be moved and remains in take-off/landing position throughout flight. See also Retractable Landing Gear.