You SHOULD use momentum on rows, sorry guys. Not a ton. I explain it like this, you don't want them to be strict, so put some "body english into them" to remove the biceps from the lift and really put your upper back into it, but make sure it doesn't turn into a powerclean to the belly.
Narrowish grip, a little bit of leg cheat, torso closer to 90 than 45, but not AT 90, tuck the elbows and bring the weight to the xyphoid process or lower.
Please note that for fat guys, upping the torso angle can actually increase the ROM. I weigh 310lbs, I am not a fat tub of lard, but I am a chunky guy, as as a result my belly is in the way much more if I am totally bent over, than even at say, an 80 degree angle.