If your building your own fixie (which you should be!) you will need an epic frame to start with, something pretty, something light, something that suits you. Forks, handles, seat, wheels are all important but what are they without a fixed gear bike frame? Single speed frames come in all shapes and sizes, typically a track bike frame they are lightweight and often made from thin tubing. You do get carbon frames but we arent all swimming in money! So buy a good fixie frame, something that feels right, looks good - its the start of a wonderful fixed gear bike project, so make it a good 'un.
...Fixed Gear Bike Frames
Fixie Frames Rock
The basis of all good bikes, the frame is the key to a totally awesome and bespoke fixed gear ride.