Hi,
I´m from Chile, near Santiago City. I did a trip from Puerto Montt to Santiago and there are 1016 Km if you go by Panamerican route, the most short. But this way is so ugly, you could to do this journey in 20 days, ciclyng by beaturifull places like montain or beach.
If you do this journey you must visit places like Cajón del Maipo (glaciar) or Pichilemu beach in Chile Central. In south, Conguillío National Park, Pucón , Panguipulli, Valdivia, Frutillar and Puerto Varas.
In this web you can see pictures and data about this journey:
http://www.ciclonautas.cl/galerias/lafrontera/galeria03.php Conguillío
http://www.ciclonautas.cl/galerias/huemul/index.php Puerto Montt to Santiago and Valparaíso
Good luck in your trip!
Mariela