I do them at qyite a vertical angle. I feel it in my lats though by pulling my elbows back. i work up to over 300lbs. Doing 135lbs @ 90 degrees is unomfortable for me. I do keep my back straight and lower back tight throughout.
thats like a dorian yates style,,, 45 dgree angle as opposed to 90 like old timers, like arnold franco etc., look at them do rows,,, they used to stand on a bench or block to let the bar down low.
theres a few dy vids on md,,, someone posted links here a few days ago and dy gave a back demo and explained his theory on rows and not bending forward too much so....
bb'n is all about more than one way to skin a cat. i started bb rows in a gym where the old school 90 was the way so if you didnt do them like that you werent doing them right so i started light and worked up after a yr or two. the move is always uncomfortable thats part of the move, keeping back str8, bent at hip, tuff to breathe etc...
always thought halfway was half bentover row and uprights.
bb rows are cool.
for the dudes that hav tufff time wit em do seated cable rows, close or wide grip, similar bc it works the horizontal plane without havent to bend to use gravity