adjust gear ratio according to top speed or to cell count?

[lincpimp]

If you plan to race the track will most likely only allow for a certain speed, any more will be counterproductive.

Plus the motor you ahve will only be good for use with one or 2 different cell counts. Meaning it will work best with a certain voltage. More info may be useful.

[mistercrash]

I'm running the MMM combo that came in my E Revo Brushless Edition. You're right about a certain speed. I'm aiming for 38 - 42 no more. The more I think about it, the more I tend to want to race with my 4S packs. Controllable power if you know what I mean. I'm also running LST diffs in this Revo. Is 54 spur/23pinion on 4S acceptable or will it make my ESC and lipos over heat?

[lincpimp]

Originally Posted by mistercrash

I'm running the MMM combo that came in my E Revo Brushless Edition. You're right about a certain speed. I'm aiming for 38 - 42 no more. The more I think about it, the more I tend to want to race with my 4S packs. Controllable power if you know what I mean. I'm also running LST diffs in this Revo. Is 54 spur/23pinion on 4S acceptable or will it make my ESC and lipos over heat?

No idea, does that gearing give you around 40 mph? If so you should be fine. 4s sounds good for racing, 5s may be a bit too much!