well if you're changing the speed the motor is turning you're also changing the torque it's producing. the lower the rpm an electric motor turns the higher it's torque, peaking at 0. Also by turning the motor on and off you're effectively lowering the torque by having the motor off a portion of the time.
To be an AGD supporter, one cannot be an AGD bigot. -Nero
Truth is a complex thing. One must govern by simplicity. -M. Mercier, special counsel to his Majesty for domestic matters. The Brotherhood of the Wolf
"You can't outrun Death forever, but you can make the bastard work for it."