Any other way to keep the chain from hitting the tire besides getting a narrower tire, or with the tensioner? I don't want to go any narrower with the tire than it is now, and the chain keeps hitting the knobs on my tire. Sometimes when I ride it jerks kind of violently. Also, my frame is kind of damaged so using a tensioner in that spot isn't an option. My sprocket isn't concaved, and my wheel cannot be pulled more to one side or the brakes will not work.