These are bad to the bone once you figure out how to do them. Set up the "stops" so you can enjoy this dead-stop variation.
The main point is to pull the bar into your abs – just a shade above the bellybutton – by driving the elbows up. Don't pull the bar up with the arms – drive with your elbows.
As with any row, keep your back flat and tight and wear a belt. Watch the video, especially the last set in the drop set, and see how my body position is fixed and I'm just driving with my elbows.