Hi @Frank, I just realized you were not asking me regarding this number, you were asking to @MakerD... , anyway, the 450 number is just where the scale starts (or ends) for the Pulse Width Modulation (PWM)
In the below example, the range will be between 450 and "maximo" (maximum). The INT "maximo" should be provided by a Slider Widget from 450 to 1023 (if you are using the ESP8266) to control the maximum speed of the robot
motorA = map(motorA, 129,255 , 450,maximo);
GPIO0 and GPIO2 are just the outputs used from the ESP to control the motor "B", GPIO4 and GPIO5 to control motor "A"
You can connect the outputs to a Dual H Bridge Stepper Motor Drive Controller Board.