noun
fixed gear (bicycle)
Refers to a bicycle drivetrain where the rear cog is fixed to the hub, so the pedals turn whenever the wheel turns. Common in track cycling and fixed-gear street bikes.
彼は固定ギアの自転車で通勤している。
He commutes on a fixed-gear bicycle.
固定ギアはトラックレースでよく使われる。
Fixed gears are often used in track racing.