Whats this gear ratio?

So I just rebuilt my drive base completely and used a different gear ratio. It is Mid-sized gear to the smallest gear. What gear ratio would this be?

There are 5 gears on each side. Small-Mid-Mid-Mid-Small

I think you mean 36 tooth to 12 tooth, which would be 3:1. Pictures of the gears you are using would help, though.

Try and do some more research next time before you post. FIrst of all, we need to know the number of teeth on each gear. Then you calculate the drive over the driven. An example would be 36 or 12. Or 3 to 1. However, the only thing that matters is the initial drive and the final gear. If you wheel is on a 36 tooth gear. Then you are running a 36 to 36, or 1 to 1.

Here is a link that might help explain https://www.sae.org/binaries/content/assets/cm/content/learn/education/motortoycar-samplelessonplan.pdf


Yes thats what I meant. So to find the ratio its Big-Tooth(x) divided by Small-Tooth(x), if that makes sense.

Not necessarily. Check out this Knowledge Base article for some more information.

(I know this thread is in the IQ Category, but the information still applies)


It doesn’t matter what are the gears in the middle. Your gear ratio is based the one attached to the motor (driving gear), and the one attached to the wheel/last gear (driven gear).

All of the middle gears are called idler gears. So, if you have the same Small gear on both, then it’s a 1:1 gear ratio.


Just to add on to all the other great information here, here is a great video from VEX explaining VEX IQ gear ratios:


Careful with blanket statements like “only the first and last gear matter”. If any of the middle stages have two gears riding on the same shaft, then the middle gears absolutely matter.

The second picture on this site shows an example of that.


Thanks, SCFarrell. Yes, if it’s set at compound gears, then the ratios would based on the multiplication including gears that are on the same shaft. 12 tooth to 36 tooth, and on that 36 tooth is a 12 tooth to another 36 tooth, then the ratio would be 1 to 9.