Need some help with World's car pinion gear recommendations

[Regulatori]

I'm finally getting around to getting my World's car (re-release) on the road and have questions about pinion gears.

The car is stock with a Power Hobby 21t (16500rpm) brushed motor, 7.2v 6 cell 3000mAh NiMH battery, and a 1060 60A ESC.

I ordered a set of 5 pinion gears with a range of 19T-23T.

What pinion gear would you recommend starting with the Stealth tranny's 81T spur gear?

And what kind of negative acceleration characteristics would make me want to go down/up a gear size?

Thank you.

[juicedcoupe]

Here are the baseline recommendations from the manual.

Other than a little less top speed, gearing down a little has no disadvantages. The motor will run cooler and likely last longer. Run times will be longer.

[Regulatori]

Thanks but I did see that.

Wasn't sure how my 21T compared to those specific Reedy motors on the chart. Figured I would start with a 19 pinion because my motor seems to be the closest to that listed 19T Reedy Super Stock.

I'm just curious of the real world results of going up/down a pinion gear size based on my setup above. Like what scenarios would I want to go up or down a gear size? (examples...poor acceleration or top speed, issues with traction on acceleration, etc...)

[juicedcoupe]

Several things can effect gearing requirements. But monitoring motor temperature is the best indicator.

Running in grass puts some drag across the bottom of the vehicle. This puts more load on the motor, requiring lower gearing.

Larger capacity batteries increase run time, requiring lower gearing to prevent overheating the motor.