Hi Nancy,
Awesome! I am cycling between San Martín de los Andes (arg) and Ushuaia, in Coyhaique, Chile at the moment... you will have a blast on the trip, I have met quite a lot of cyclists doing similar routes. If you need maps when it comes to Southern Arg/Chile I am happy to scan what Í've found and send them to you...they are very difficult to come by (read: impossible) in the US. The roads down here are tough...I've hurt my knee and unfortunately will be taking more buses than I would like. If I only had 30 months! (which doesn't seem like so long, actually!)
Anyhow, you will have a great time!
Anne