This year CV Robotics did our first custom gearboxes since 2008, because we wanted a more durable and flexible to our design option. When I calculate the speed for gearboxes I design, I usually just do a rough calculation (eg. stoichiometry to get from CIM RPM [5000ish] to feet per second). Using this I can compare it to previously used gearboxes to see about how fast we would be going. This year's gearbox was calculated at around 18ft/s:
https://www.youtube.com/watch?v=feS_KxnsZ8s
You can see our robot on the far side in red here:
https://www.youtube.com/watch?v=3UlV...DIBcQ&index=61
The robot may not be going 18ft/s, but next year if we want a faster robot, we can change the gearing so that our calculated value is a little larger, maybe 21ft/s.
Hope this helps,
Michael