ESC Timing - what it is and how to choose it

Some ESCs will allow you to choose the "timing" often low, med, high. This is very like the timing of the ignition in a car and sets the number of degrees of "advance". The stator windings need to reach peak magnetic field strength at the correct time relative to the position of the rotor. This correct position varies with many things but the size of the motor tends to be the one we can most easily see.

In electric motors the required timing relates to the rate at which the windings magnetise and de-magnetise when power is applied which is in turn related to the size of the winding. So bigger motors with bigger windings work better with more advance to offset the delay caused as the winding magnetises/de-magnetises. Put another way round, because it takes a bigger winding longer to reach peak magnetic field strength when voltage is applied the brushless ESC must begin applying that voltage earlier to get the winding to a condition where it can most effectively pull the rotor around.

Setting a low timing (less advance) on a big motor will make it slow to accelerate and high timing (lots of advance) on a small motor will just waste energy as heat.