I need a Chain ring guard for a Giant Boulder that I have. It is a 21 spd, & a few years old. I cannot find a replacement from Giant dealers, or other bike shops. Seems like this would be an easy item to find. Ring would be about 8" diameter [ 200mm +- ] & 5 bolt pattern being a diameter of 6 1/2" [ 165mm +- ] Anyone have one, new /used, doesn't matter. ?????