Carl Larsen did a useful tutorial showing how to use expressions to accurately rotate wheels to look like they are rolling across a surface. I seem to remember they also worked for different sized wheels
I'm sure those expressions could be useful in figuring out your problem.
Each link in the chain will pass through four states.
1) On the first gear
2) Passing from the first gear to the second
3) On the second gear
4) Passing from second back to first
If you can solve the total length of the chain, you can solve the speed each link will move around the chain's path in terms of the speed each gear rotates.
To solve the chain length, you need to solve the length for each of those four parts. The angle around each gear that the chain passes along will add up to 360, so if the larger is 190 degrees, the smaller will be 170.
The tricky part to me is how to figure out what those two angles should be.