[BrianG]

There should be a sticky about this type of topic since I know this has been covered numerous times, but here goes:

For a given voltage and speed, it does not matter if you use high kv and gear down or use low kv and gear up; the amount of work being done is the same. Low kv motors geared up will pull roughly the same current as a high kv geared down.

The advantage to using low kv is you have a little headroom to run with higher voltage if you want to go faster. If extended runtime is the goal, use higher voltage and lower gearing. Every motor has an efficiency curve, and most of the good models are pretty good all the way up to 50k. GriffinRU's program demonstrates this.

The advantage to using higher kv and low gearing is that there are more rpms per mph, so at really slow speeds, the chance of cogging is reduced since the ESC can get more back-EMF pulses for efficient commutation. You may be physically limited by the size/availablitity of the spur/pinion too.

There are limits to each setup. You can gear up a low kv system so much that the batteries and ESC run hot trying to deliver the acceleration current. You can gear down a high kv system so much that the motor is running over its peak efficiency.

Personally, I prefer higher kv and lower gearing for lots of start/stop style of driving. Starts and acceleration seems smoother. I shoot for ~40k-45k rpm on the good motors (Medusa/Neu). If I was doing just speed runs, I would probably go the other route since starts aren't as important.

BTW: mjderstine, I'm not trying to be short with you, I know sometimes it's hard to search when you don't know the exact search phrasing...