Tethered Zumo mini sumo motor help

My 6 year old is building a tethered mini sumo. I was thinking 100:1, 150:1 or maybe 298:1 would there be a big difference in speed? Any suggestions would be great before I purchase some motors.


The speed of those gearmotors is approximately proportional to the gear ratio, so a 150:1 gearmotor would turn about 3 times slower than a 50:1 motor. Our 100:1 gearmotors are the slowest we typically recommend for the Zumo robots.