In Dan John's book (From the Ground Up!) he states that if you feel the RDLs in your lower back, you are doing them wrong. You can download this great book for free here:
and I'll get $1 for each download I refer.
Nah, just kidding.
There are great explanations to a large number of exercises, but beware of the technical jargon Dan sometimes throws around. For example, he might say something like "if you don't feel like your hamstrings are going to be ripped off your backside, then you're not doing the exercise correctly."
He certainly knows how to get a point across!