Just so everyone reading is aware, there are some serious safety issues with field weakening.
If the motor is powered into a faster spin than its normal no-load speed, then any ESC failure would feel like an immediate full-brake, likely to pose significant danger to the rider. A lot more danger than a regular ESC failure at top speed, which would likely just put the board in “neutral” or “coast” mode.
Only do this at your own risk. 