Originally Posted by
bikethis
Unfortunately my frame won't allow for anything larger than a 42T.
Tell us what your bike is and what crankset you are using and we might be able to help you more. (Not being able to use bigger than 42 teeth? It's an unusual bike that won't allow bigger with a standard crankset if it as a regular road bike that takes 27" or 700c wheels. Most single speed and fix gear bikes and wheels are designed to use a chainline a set distance from the center of the seat tube. (42mm if I recall correctly.) That chainline virtually always allows as big a chainring you you can get.
Chainlines - they should be straight for SS and fix gear. You should be able to sight up the chain from the rear and see no "S" turn to it. If your bike is a conversion from a double or triple, it may well be that the small chainrings are inside that proper chainline and not aligned with the rear cog. (Knowing nothing of your bike or setup, this is all speculation. But Diablo Scott's comments may well be on the widths of various types of cranksets pressed into single speed duty.)