I'm looking forward to kick off from Santiago or La ligua on my way back home africa. (www.chiletokili.com) This will depend how soon chilean will scribe the visa in my passport then I'll be cycling from Santiago to Peru. Just wonder if there is anyone who is planing or interested to hook up, it will be real fun, to be honest this is my first time out of mother continent so I still have to fugure out a lot how to use roads, find camping and so on.
I just took the road from La Ligua to Copiopo in December...here is my journal
Camping is not a big issue in Northern Chile, but it is not always easy. Instead of stealth camping, I actually asked people in some cases if I could camp adjacent to their land...they were generally welcoming and actually were pretty protective. It was nice staying in a hotel every two or three days. There is really not a lot of formal campoing areas if you are off the tourist trail, and the road from La Ligua is off the trail.
A couple of insights. First you are safe in rural Chile because no one is just driving a car around for entertainment...there are no teenagers out driving at night.
You may want to learn some Spanish...out of the major cities, no one speaks English.
Make sure you have the capacity to carry 10 liters of water...there are often long gaps between available water.
You shouldn't be alone too long cycling in south america. Lots of people around there (depending on you route of course) Less going your direction but I've still met quite a few of them around Ushuaia when I was there end of last year. Depending on when you start, some might be around to pedal along.
I do recommend the lagunas (and the salars depending on the season) in Bolivia. It's a tough climb from San Pedro de Atacama and you might be pushing from time to time, but it's gorgeous !