Training & Nutrition - "Zone 1-2" Rides

This question is for those of you who use Joe Friel's book(s) as a guide for training. Many base period rides are in Zone 1-2. Being a classic overachiever, I tend to shoot for the middle/high end of Zone 2 for these rides except for my easy weeks. My only concern is, is it important to hit Zone 1 for extended periods, or is it alright to stay in Zone 2?

Depends what you want to do. To answer your question, yes. Generally though, Z1 is for active recovery; Z2 & 3 are at endurance pace. Traditional base is typically high Z2-3.

Most racers have adopted SST training into their base periods, or Sweet Spot Training: it's high Z3 and low Z4. Do a search and you'll find a ton of variations in the racing forum

If you are not racing, the traditional base period is great for recreational rides etc.

Friel has actually modified his recommendations since the printing of the book. He said something about "noodling around" in zone 1 not being effective use of valuable training time. It seams his more recent recommendation focuses a good amount of time at Aerobic Threshold (AeT) which he calculates at 20 beats below Anaerobic Threshold (AnT). I think for most people that puts you 1-3 beats from the top end of zone-2.
Article On Aet (http://trainingbible.com/pdf/Determining_Aerobic_Threshold.pdf)
Base Training Article- Friels Blog (http://www2.trainingbible.com/joesblog/2008/12/simplified-base-bicycle-training.html)

Thanks. I do race time trials, but none long enough that would require a serious base period. However I am interested in fast centuries and metrics, so that requires a reasonable amount of aerobic conditioning.

What you describe as AeT is just about where I tend to be for my "Zone 1-2" days, so I'll have a look at it.