The most important part of any bicycle is the frame. For a fixie, most any road bike frame will do, but there are a few things to consider.
First of all, when choosing a frame for your fixie avoid frames with vertical dropouts. The dropout on a frame is the slot that the rear wheel slides into. Because of how the chain tension on a fixed gear bike works, only frames with horizontal or semi-horizontal dropouts are acceptable for building a fixed gear bicycle. The reason for this will be discussed in more detail later, but for now here are a few examples of dropouts that will work and dropouts that will not:
Second, it's very important that you pick a frame size that is right for your body type. A good frame should be short enough to easily get on and off, but tall enough so that you don't have to stretch your legs to pedal. If you're still having trouble figuring out what size is right for you here is a calculator that will help.
Lastly you'll want to think about what material your frame is made of. In general the material wont affect your ability to convert any bike into a fixie. However, different materials differ greatly in price and they can drastically affect the feel and comfort of your ride. Of the four most common frame materials steel, aluminum, fiberglass, and titanium, for this project I would recommend a steel or aluminum frame. This is because fiberglass and titanium can be extremely expensive even when bought used. Aluminum frames are light but many people dislike them as they tend to offer a harsh ride. Steel frames on the other hand tend to be heavier but offer a much more comfortable ride. In the end it comes down to personal preference.
But where do you find a bike to convert into a fixed gear? For this guide I'll be restoring an old road bike I found after a bit of hunting at a local thrift store. You should also try visiting garage sales or browsing craigslist in search of a project bike. You might also consider converting a road bike you already own into a fixed gear. Here is the bike I'll be using:
Once you've found your bike you're ready to start taking it apart.
