The first place to start is to subscribe to the framebuilders list on Google groups, lurk for a few weeks, and then start to ask questions. There's some very knowledgeable people there, and the signal to noise ratio is very good.
For me, I was reasonably sure what I wanted to build as my very first frame. I'd raced criteriums and road races for a few years, and had recently adapted an old road bike into a fixed wheel - a sort of road/track mongrel with no freewheel, one fixed gear, and brakes. I figured the next logical progression was to do track racing, so the obvious frame to build was a track frame.
This was a good choice of first frame because there were a minimum of additional bits that had to be added to the frame, complicating the build. What did complicate the build was the non-standard geometry due to the high bottom bracket, which meant that I had to do a lot of metalwork to the bottom bracket shell to get the frame to work.
On reflection, I think I should have started with a basic road bike first. Something with very standard angles, to simplify the process. I think you should, too. Road going fixed wheel bikes are also cool. One of my friends started with one of these, and had great success. Shelve those ideas of a fully suspended mountain bike or stainless lugged masterpiece and build something straightforward.
For the rest of this tutorial, I'm going to assume you're building a basic road racing bike or light tourer. I've done a few that fit into this category, so I'm going to borrow from the experiences of each of them in order to illustrate points and the myriad of options that present themselves.
Sizing is very important. No bike will work well if it doesn't fit you well. I've had a number of different bikes over the years - some too big, one too small, and the more recent ones pretty much right. I had a good idea of what the top tube and seat tube dimensions should be, so only had to work everything else out before I had a design that was buildable. If you're thinking of building a frame, you're probably a bike nut like me, with half a dozen bikes occupying various rooms of the house. These are your source of inspiration for sizing. Measure what you already have carefully, and put some thought into what you'd change if you had the chance. Could you do with more length, or a faster (steeper) steering geometry? Or longer chain stays, so you don't touch them with your heels?
My first frames have been silver soldered lugged steel. I like the look of lugs (except when they're overly ornate) and think it's a practical, strong way to build a frame. Also, I've never used a MIG or TIG welder before, so thought I'd stick to brazing.
Here's a detailed drawing of a standard 54cm road racing bike:
This frame would be called medium in most bike catalogues. It will fit an average height (175cm) male adult, with average proportions. The chainstays are relatively short, at 410mm, to make for a lively ride and to reduce the wheelbase. The 74 degree seat tube angle puts the rider's weight forward. The combination of 72.5 degree head angle and 45mm fork rake give neutral steering trail of 57mm.
This is the sort of frame I'd recommend for criteriums, road racing, or fast weekend rides. You should use this frame as a template to design your own.
My preferred tool for designing bicycle frames on the computer is Draftsight, by Dassault systems. This is a free 2D CAD program, which reads and writes industry standard .dwg files that can be used in practically any decent mechanical CAD tool. It's not bike specific. It won't let you try on different colour schemes etc easily. But it will let you draw with accuracy and find the dimensions you'll need when building your frame (or jig, or workbench, or what-have-you).
So off you go, take a tape measure and protractor to your favourite ride, download Draftsight and do their tutorial, and I'll see you back for the next step.
