The best option for a chain driven base would be a "West Coast Drive." Do some research on this drive-train, as it is mainly used in FRC.
The Middle wheel is normally geared and driven by one or two motors, located in the middle, and bottom of the robot. From the Center wheel, two separate chains going to each outer wheel. If your chain was to snap, or fall off, then the center wheel would still be moving.
Also, go with bigger sprockets on your wheels. Do not go with a 16 tooth sprocket. If at best, only 8 teeth of the sprocket are engaged with the chain. I would recommend going with a sprocket that has 32 teeth or more.
While we did not create a true WCD, you can look at our drive-train on our twitter and YouTube pages. The main issue with our chain: If the chains snaps that are connected to the motors, we loose the whole side of the robot. Also, I would recommend having both sets of chains on the between the wheels and frame. (We had to move one set outside of the wheels due to motor length.)
https://twitter.com/trojans8640?ref_...Ctwgr%5Eauthor
https://www.youtube.com/watch?v=Cjy5xm3vSQk