[jdiwnab]

The model is very complicated and while there isn't a specific weight limit, you still don't want to be too heavy. Only the outer shell needs to be sphereical, not the frame inside. If you use tread like shown, then the tread on the sides would need to slip in order to go. this could create problems with driving and wear and tear. By putting a bar outside, and by making part of the sphere flat, you almost defeate the purpose of having a sphere bot.

I worked with Squril Rock (sp?) on this idea and we think the best thing would be to have a 1/2 structure withat has like omniwheels at the bottom. you could drive in any direction and if properly ballanced, the sphere would roll and the bot inside would stay upright.