FYI. I picked up a harken low friction ring at my local sail shop. Cost was like 30 $ Canadian without tax. The size is 20mm and 14mm thick.
It is incredibly smooth, as smooth as a pulley I would say. I actually would prefer a little resistance as its slides across.
Purpose of using the ring instead of just a chicken loop is wear. The line will wear that cl down for sure. I'm careful to always be sure the cl is on the ring, it will only pop off after a major crash.
The the ring is actally a little small for the cl with regards to thickness, but it turns out to be a good thing. As the cl has a thick polymer cover it wedges into the ring under load and thus prevents it from separating from the ring if you lose line tension.
One last thing. I found with this set up the bar moved too far from my body so I changed out the cl for a women's cl. Now it's much better for me. Cost was like 25$CA but I don't have the time to modify a CL.