double-declutch

Double-declutch is a driving technique for smoothly shifting gears in vehicles with unsynchronized manual transmissions.

The driver depresses the clutch, moves to neutral, releases the clutch briefly while matching engine speed, then depresses again to complete the shift.

The technique was essential before synchronized gearboxes became standard: He double-declutched down to second before the hairpin.

Also called double-clutch in American English.