I wanted to follow up on this thread. I have the same question. It was never really addressed in the thread.
Even trying to "hinge at the hips" I still get moderate sciata nerve pain doing the Jefferson curls, even with lower load, like 45-55lbs. This of course can is not inhibiting to the exercise if it's minimal (though it is if it is stronger). I've been doing Jeffersons for about 2 years and while the exercise has gotten much easier on my hamstrings it still feel it in the nerve.
I have two questions..
Do you recommend "Flossing" or other exercises to minimize the sciata? Is feeling more sciata pain a sign of a specific weakness in the exercise? I feel it in many exercises so it is a general problem for me and something I need to address.