I would even think that your ESC should handle a 15 or even a 16T pinion depending on grip with this very high revving motor. On 5s your motor could spin well above 50000rpm. The Neu 1512 i use already reaches 40000rpm and is geared 13/52. I thought this is already crazy.
Think about the torque you will have on tip when you gear it down. Your front (and rear) tires will have a hard time to keep up. Spin city ... Prepare to stock up on tires. But it should be fun to drive it this way
