Hey, im new to single speed and fg bikes, but i LOVE the look of them. I used to ride bmx alot, so im used to the single gear. Im currently looking around for old racer bikes, with the intent to convert it and make my own fg! just have a few questions, do all fixed gear have those "crank brakes", when you pedal backwards? id build mine with just a front gear! how much on average did your entire rig cost to build, from scratch to first ride? whats the easiest way to figure out a comfortable gear to ride fg without wrecking my knees? any advice would be greatly appreciated!! what is chain alignment, and what is the aim of it, to have a chain parallel to the wheel or what?? any advice please, thanks

The crank brakes you speak of are either a coaster brake on a singlespeed/internally geared hub or the fact that you can resist the pedals ona fixedgear because you can't coast. My conversion cost me around 400$ and I swapped all those parts to a nicer frame later, but I replaced every part except for the frameset on the conversion. A kilo tt would have been cheaper, but I've always liked building bikes. As for a comfortable gear to choose, just borrow a road bike and try every combination without ever coasting. Finally chain alignment is how straight your chainline is, most 120 spaced track hubs will give a 42mm chainline so you want to match your bottom bracket spindle length up so your chainwheel matches 42mm

Edit: read sheldon browns website till you have it memorized

...or go to the site in Circa85's avatar and join a friendly group of guys & gals who used to post on this site but we've left for grander pastures because half of us were banned or are friends of those whom were banned so we decided to go to a censor free environment .... and we'll help you on that build of yours. run on sentences are awesome.