I'm a cyclist in Cordoba. Here are some links to cycling and bicycle advocacy groups in the area:
http://ikers.com.ar/ http://www.biciurbanos.blogspot.com/ and
http://masacriticacba.com.ar/
I was huge road biker in the States, mainly a commuter, but found lots of time for epic weekend rides. When I moved to Cordoba, I bought a mint condition, manual shifting, all-Campagnoloparts and tires 1970's road bike (for 1500 pesos) and later, a mountain bike. In the past two years, I have begun to favor the mountain bike. Here's why:
The roads are HORRIBLE.
To get out the Sierras, you must first bike through 20 km of giant pot holes, broken glass, rocks and other crap that will give you flats. Once you get out to the Sierras, the roads improve, but there are NO paved shoulders.
Most of the paved roads in the Sierras are major thoroughfares. You will be sharing the roads with slow-driving lost tourists, giant trucks in transit to La Rioja, and 'local' buses that stop every 100 meters, making passing or getting passed a real hassle.
One time riding alone, I was stopped by a police officer in the Sierras, who told me to pull over and ride on the dirt shoulder (on my road bike) so buses could pass me! Obviously this would be different if you are in a group.
In the States, I loved riding my road bike on quiet backroads in the Appalachian Mountains. In the Sierras, all the quiet backroads are
unpaved. This is one reason why mountain biking is so much more popular here - it makes for much better riding.
Here, I have a favorite 60 km and 100 km loop on the road bike, but both of these only have about 20 km of beautiful mountain riding, the rest is heavily trafficked. The further you get from Cordoba though, the less traffic. I think the Sierras would be perfect for bike touring, ie going for 3-4 days or longer on the bike.
Road Bike parts are increasingly not available.
Argentinian bike companies do not manufacture road bike parts, only mountain and playera. Due to import restrictions that I do not fully understand, road bike tubes are becoming increasingly difficult to find, even in Cordoba's largest best bike shops. The only road bike tire available is the racing 23 cc, which I found horrible for dealing with all the potholes. On a recent trip home, I purchased new burly 28 cc tires and brought back 6 sets of new road bike tubes.
You have lots of options for mountain bike parts and tires though, and because they are produced domestically, everything is much cheaper.
Remember to bring all your gear and accessories (helmet, pump, light, repair kit, ect.) with you, because you won't be able to find good quality stuff at good prices here.
In my opinion, San Juan and Mendoza are really the best places for road biking in Argentina. Many more road bikers there than in Cordoba.
I don't think safety is big concern in the Sierras. Just bring a lock in case you plan on stopping and going inside somewhere.
The cars will drive much closer to you than in North America, but in the Sierras, it is not in an aggressive way. You will get used to them honking at you, usually it is to let you know that they are passing you.
That being said, I ride all the time. I love biking here, road or mountain. I still go on long weekend rides, and you will find lots of other road bikers who do. Let me know when you get here and we can go for a ride.