The install instructions suggest to use the same size of bearing for the connecting rod. Didn't like how the holes ended up so I made my own (thicker and longer). The rod is 1/2 inch in diameter, but the hole (drilled with a fostner bit) required some sanding to fit. I removed a rivet that interfered when I drilled the blocks in place, as I plan to put it back in, I made a clearance for the manufactured rivet head.