A droopy looking guy watches an ammeter. Dozens of identical Midgets Operating a big Switch For Each Thumb (MOSFETs) sit in rows at their panels.

The Controller sits at the command center, listening to the phone.

Dozens of hands shove dozens of switches closed, all in unison. The current slowly begins to build. The mighty electric vehicle begins to move majestically forward as the microseconds pass.

At about quarter past, Droopy clears his throat.

Acceleration stops, as the motor's current diverts to flow through the freewheel diodes. The motor is just coasting now. Current slowly falls as the motor resistance causes the current to gradually decay.

The MOSFETs all close their switches and the cycle repeats.

However, with a big, low inductance, low resistance motor, the controller can't switch off fast enough to properly limit the current. Excessive current means excessive torque, which means a jerky start. Like this :

The current rises fast, inspiring a tremendous burst of acceleration. Within microseconds, Droopy sees it climb all the way through the green, the yellow, and into the red zone.

Current shifts to the freewheel diodes. But because of the low resistance, it doesn't fall. It hangs there, barely dropping as the microseconds tick by.

This process continues, with the motor current above the desired value because the controller can't respond fast enough to limit it.

This is why Curtis changed their C models (1221C, 1231C, etc.) to reduce the clock speed from 15 KHz to 1.5 KHz for throttle positions less than 15%. It gives the controller 10 times as much time to let the current drop before the next turn-on cycle. You may hear an audible tone, but the motor will start smoothly with no jerk.