I have a small problem. I was silly enough to expect that when I put a couple of wrenches on the three "nuts and bolts" on my chain wheel, that they would unscrew and come off. Nope. They spin both directions if I want, but do not come off. It seems like more of a rivet system. The bolt side is 7/16" and the nut side is 1/2". Any ideas what is going on here? Also, does anyone know what the other fasteners are called? They are tubular threaded fasteners. In the picture I show three of the six.
Thanks,
Marv