We spent several uneventful days in the Valle de Uco region of Argentina, dismayed to see unseasonably cold and wet weather and beginning to despair of our planned return. But the snow melted and we were able to make our second crossing, this time using the little-visited Portillo Argentino and Piuquenes pass. This was the highlight of our trip. We had organised mules from England and certainly needed them. There is a rough road as far as the Portillo Argentino, but from there to the Termas del Plomo in Chile there are only mule tracks, often hard to push let alone ride. Between the passes is a beautiful uninhabited valley surrounded by high peaks; the Río Tunuyán which runs through it cannot be crossed except on muleback.
We left the mules at the Paso de los Piuquenes (they are not permitted to cross the frontier) and completed the journey on our own, pushing the bikes down to the Río Yeso and crossing it the next morning with rope for (questionable) protection.
Finally we spent a couple more days in mountain scenery at Lo Valdés before returning to England.
The route notes are spread over 6 pages. There are 3 maps in addition to the one above. The map of Valle de Uco (at double resolution) is there to correct errors in the Turistel version; the Piuquenes crossing map (also at double resolution) gives a good view of the route; the sketch of the Piuquenes descent may be of practical use.
There is also a page of general info, a page of links, a page of GPS readings for the Piuquenes crossing, and a page of reflections on this part of the route.