Let's Make Robots!

speed reduction

Gear motors... too slow?

I was looking for small gear motors and I found two nice ones: http://www.robotshop.com/ca/solarbotics-gm7-gear-motor-7.html and http://www.robotshop.com/ca/solarbotics-gm10-geared-pager-motor.html. The first one has a 120:1 gear ratio and the second 81:1. Are these ratios too slow for a robot about 6x6 cm big?