1) Autobot 2) Move to a lower gear 3) Slow without braking 4) To become less active 
to shift to a lower gear, i.e. a larger cog or smaller chainring.
to shift to a lower gear, i.e. a larger cog or smaller chainring.
To shift into a smaller, and thereby easier, gear ratio; e.g. from the big ring to the small ring or from a smaller cog to a bigger cog.
to shift an automotive transmission or vehicle into a lower gear. · to become less active; slow down: The economy seems to be downshifting.
A downshift can occur whether you’re manually shifting gears or in automatic mode. This is the process of a transmission moving into a lower gear from a higher gear. This happens prior to or while braking, in order to allow the car to utilize power after a turn is executed.