Zumo 32U4 Robot, 50:1, 75:1, or 100:1 gear ratio... which one to choose?

Hi all,
I have to decide which Zumo 32U4 model to buy: assembled with 50:1, 75:1, or 100:1 motors?
I’ve found no discussion about it in the forum, but I may be wrong, in which case please excuse me.
The three different assembly options give different speed/torque: 50:1 is the fastest and 100:1 is the one with largest torque (not so much larger, as explained at https://forum.pololu.com/t/gearmotor-double-gear-ratio-double-torque-why/8121). I need the robots for my coding and (elementary) robotics lessons (school and university), so I don’t have precise needs: I’ll experiment with some obstacle avoiding, maze exploration, sumo, and (after some tweaking) communication,
I don’t need extraordinary speed, thus I’d probably choose 75:1 or 100:1.
What is your experience?
How slow is the 100:1 model?
Some comments about it by the Pololu engineers and by other users would be welcome.
Best regards

Either this was an extremely stupid and trivial question, or it is a really arduous one :smile: !!


The 75:1 gear ratio Zumo 32U4 is probably a good choice; we think that it has a good balance of speed and torque. Since the speed is proportional to the gear ratio, the 100:1 gearmotor would only be capable of roughly half the speed of the 50:1 gearmotor. If your Zumo 32U4 robots are likely be used in competitions against each other, so as long as the two robots are using the same gear ratio motors, speed is probably not as important of a factor, and the programming skills of the students would ultimately be what is tested.


Hi Derrill, thanks for your kind reply. In point of fact I imagine the 75:1 ratio is the best compromise.
Just one more question; in the example video:

is it known what gear ratio is used in the various examples?

The Zumo robots used in those examples had a few different gear ratios. Most of them used 75:1 gearmotors, but if you go to the YouTube page for the video, you can see information about the gear ratios of each Zumo used in the description (once expanded with “SHOW MORE”).


Thanks, Derrill… how stupid I was… the information was there and I had not seen it. In point of fact I’ve generally watched the video from https://www.pololu.com/category/170/zumo-32u4-robot and not on the youtube channel, so I missed it.
Thanks again! Now I have some more elements to decide.
Best regards

Does anyone know the actual horizontal travel speed of the three gear ratios?

I just found the speeds. They are listed in a table here.

50:1 40 in/s (100 cm/s)
75:1 25 in/s (65 cm/s)
100:1 20 in/s (50 cm/s)


Hi again!
No point in opening a new thread just to let you all know I am now a happy owner of six Zumo 32U4 75:1! they’ve arrived yesterday, so I have not had the time to do anything but taking one of them out of the box to have a look. I’ll start experimenting soon, and I hope to (1) use them in my courses at school and at the university (I am a physicist, researcher and teacher) after (and together with) my self-built arduino based robots, (2) play with them in mazes and self-organized minisumo competitions (3) modify them (yeah, how brave - and crazy - I am…) by adding another arduino or a raspberry pi or a cell phone or anything else on top to make them more intelligent (I love computer vision, so this is a field I’ll explore).
This is all!
Best regards