You might have a spindle made for a narrower BB than you bike has. There are at least 3 sizes of spindles. They are made for 68 mm, 70 mm and 73 mm BBs. If you are trying to use a 68 spindle in a BB that that is 73 you will never get it tight. 68 is standard, 70 is Italian and 73 is many mountain bikes and maybe Surleys as well. Roger