yes, they work very well for simulating a proper forward stroke. I do races and am building one, using a fanwheel assembly off a Concept 2 rower. The lines don't really need to rotate and I'm not 100% sure why the clip is there. I just assume it makes replacing lines a tad bit easier or something..

and thanks for that other link below. . those pieces are too expensive, you are right!

Eric

: I didn't look to see what it was doing, but I have to agree if there is only
: a slight rotation just tie some knots. I assumed it needed to really
: rotate. What is this thing anyway? Paddling simulator?