[MrForbes]

Interesting! and could you try V belts too?

We have looked at using toothed belts, and #25 chain, and have always used #35 because it's easy/available/inexpensive/forgiving. The extra weight is generally down low on the robot which makes it not very important, and the extra efficiency of belt seems to be negligible.

I guess as your team gets better at designing and building robots, the importance of these paramaters shifts.