Proper chainline is very important on a singlespeed and, thus far, I've had it setup pretty ghetto with a handful of cassette spacers that I eyeballed. I wanted to run Rennen's spacer kit but they've been out of stock on it for weeks now. So the one I ordered from Endless Bikes showed up today. This is their Fibonacci spacer kit. It comes with a handful of spacers anywhere from 1mm thick to 21mm. They have a huge explanation on their site as to why the spacers are cut the widths that they are and its too technical for me to go into. I decided to do some simple math which then told me that the center of the cog needed to be 21mm in from the locknut. So then I started stacking stacking spacers until I had it the way it needed to be.