[Ian Curtis]

We have used one not mentioned in your design, however similar to the bottom. In ours we we mounted our gearboxes above our center wheels and ran #35 chain from the gearbox to the wheel. We then ran #25 chain from the center wheel to both outside wheels. This means that your center wheel will have 3 sprockets. An advantage is that you should never lose complete control of one side. However, I assume in your bottom design that you have a live axle, so you wouldn't lose control of the center wheel.

We tensioned our chain by moving our wheels, but this was pretty cumbersome, so I would imagine idlers would be more convenient to change. We never threw a chain without getting something (such as a game piece) getting caught in them.

The problem I forsee with your top design is that if you throw that chain, you're done. Even if you use #25 chain correctly its quite possible that a chain will break. It shouldn't, but always plan for the worst case. If you use #35 chain, it will be heavy. Really heavy. And if you plan to play with trackballs, you will most likely have weight problems. Pretty much everyone does.

Good Luck!