How to find the right gear ratio ?

[JThiessen]

You didn't say that you had tried this, so here is the link to BrianG's calculator http://www.scriptasylum.com/rc_speed/index.html

Originally Posted by JThiessen

You didn't say that you had tried this, so here is the link to BrianG's calculator http://www.scriptasylum.com/rc_speed/index.html

Yes, I've used the calculator, but the problem is that a calculator doesn't said which is the best possible (theorerically) value given a specific motor.

I mean, I can enter different values and get a total gear ratio and, consequently, an evaluation about top speed. But how can I find the best ratio to be used ? Is, for example, a ratio of 13 : 1 suited for a motor like the 1717 ? Is the motor so powerfull that i can, lets say, lower the ratio down to 10 : 1 ?

I don't have any specific requirements about top speed. My only concern si to be able to use the motor at its best.

Bye, Andrea

[BrianG]

Originally Posted by andreazinno

Yes, I've used the calculator, but the problem is that a calculator doesn't said which is the best possible (theorerically) value given a specific motor.

I mean, I can enter different values and get a total gear ratio and, consequently, an evaluation about top speed. But how can I find the best ratio to be used ? Is, for example, a ratio of 13 : 1 suited for a motor like the 1717 ? Is the motor so powerfull that i can, lets say, lower the ratio down to 10 : 1 ?

I don't have any specific requirements about top speed. My only concern si to be able to use the motor at its best.

Bye, Andrea

Some people shoot for a rollout ratio of 1:1 as a starting point. That usually gives you moderate speeds (a bit on the low side usually).

You can try this: http://scriptasylum.com/rc_speed/_rollout_ratio.html

Or, just plug some numbers into the top speed calc and click the little gears icon in the results area. That will bring up a table and show the pinion needed for a 1:1 rollout in bold.

[JThiessen]

I normally end up at a rollout of about 1.8 - 2.2 with my trucks.

Originally Posted by JThiessen

I normally end up at a rollout of about 1.8 - 2.2 with my trucks.

Mmh, seems a quite high value.

At moment I have a rollout of 1.35 and, considering the motor specs, I reckon I can raise up the value up to 1.5 - 1.7

Bye, Andrea.

[JThiessen]

I had thought so too, but it seems to work so far. I started using it after I put the stock Flux set up in the calculator, and it was in the upper 1.XX range (dont remember if that was before or after the BP diffs).