So I recently installed a new 15/28 sprocket setup with a new gold chain cut to size. I rode it about 10 miles and was fine. Then made it about another 5 miles and the chain came off. It was still on but it was off of the rear sprocket teeth. I put the chain on and pushed the bike back and it went ride back. I rode a little bit again and happened again. Fixed it and did it for a third time. I looked at the sprocket and saw a pretty loose screw. I tightened it and haven't riden it but I think that might have been the reason. I think the chain is tight enough because I pull on it and it hardly budges. Also I took off a master link and tried to make it a link shorter and was near impossible. Has this happened to you? Thanks!