I am working on a single speed conversion on my old trash picked bike. The derailur(sp?) didn't "come with the bike" so I was wondering what I could do with it. I took everything off except the breaks and decided to make it a single speed. I took a good amount of chain links off and it is in between gears. It is on the large cog in the front but on the back when I put it on one gear the chain is too big and falls off but when I move it to one gear bigger the chain is too small and doesn't allow the wheel to sit all the way in. I was wondering if they made such a thing as a half chain link.