From Puerto Natales I cycled to the Rio Serrano entrance to the park, via the Y-290 road, which was closed for works. However, I begged the guards to allow me to pass, otherwise a long detour on bad gravel would have been needed.
From Serrano I cycled to Mirador Grey. Then came the most spectacular and famous stretch, that along the lakes, Serrano to Laguna Amarga. There I left the bicycle and went for a trekking to which another track is devoted, namely http://www.wikiloc.com/wikiloc/view.do?id=12060871
After returning to the bicycle, I went north to Laguna Azul, and even a bit further in direction Paso Zamora. I returned south via the main route to the park. The track does not close in a loop, and rather ends in Villa Cerro Castillo, since from there I crossed into Argentina, in direction Cancha Carrera - Tapi Aike - El Cerrito - El Calafate - Perito Moreno.
Note that, if Paso Zamora were open, in a 50-60 km the cyclist could cross from the Paine to the Perito Moreno. Unfortunately, just to have the right stamp on the passport one needs to go for the full detour mentioned above - maybe 400 km in the pampa and exposed to the worst Patagonian winds.
PHOTOS: WORK IN PROGRESS